Some readers will likely remember an RX7 I mentioned in a sideline a few years back that kept eating rear axle bearings. It started when the car was barely six weeks old. The car came to the dealership for noise in the rear end, and the rear bearings were a mess, so they were replaced and the RX7 left quietly.  A few weeks later, the car was back with the same noise, and the bearings were destroyed again. After the third time, the field service engineer authorized the replacement of the entire rear axle. A month later, the car was back with the same problem, and so Mazda bought it back and sent it to one of their training centers, where the instructor found the problem purely by accident during an electrical class.

The battery-to-engine ground cable had never been tightened when the car was built, and so every time that rotary engine was cranked, the starter would find ground through the body by way of the park brake cables into the rear axle, where it arced on the bearings, then went at the speed of light up the driveshaft into the engine block to the starter housing, and the starter would spin. Enough arcs on those polished surfaces and they would give up metal and lose their luster in a big way. And after miles of driving, and nobody anywhere could look at the ruined bearings and figure out the origin of the ruination.

Problems like this one are the spice of a troubleshooter’s life, and usually after the repair is complete and the head scratching is done, we can draw ourselves a map from condition to cause to correction. Of course, we have to sort out the causes and the effects along the way, and that can require some mental gymnastics.

More recently, one of my students complained that after every time he gassed up his 2008 Kia Rondo he’d have to wait about ten minutes before the vehicle would start. That was a head scratcher too, and after a bit of thought and some research we found out that the canister purge valve was always open, and that all the vapor being shoved out of the empty space in the gas tank during refueling was being forced through the open purge valve into the intake. When he attempted to start the engine immediately afterward, that heavy hydrocarbon vapor, along with the double pulse from the injectors during engine crank, would dampen the spark plugs enough to cause the no-start condition until the plugs dried off enough on their own to begin firing again.  Careful with his money, this guy wanted to know how to test the part before ordering a replacement, and I showed him how to verify that air (and hydrocarbon vapor) could pass freely through the old purge valve no matter whether it was energized or not.

Gathering data and sorting it out requires a sharp-minded clear thinker, and everybody who’s in the know will agree that a really good troubleshooter in our field needs to be just a bit smarter than the average bear on a number of levels. So let’s launch into a couple more stories as we travel the winding road to the B2300 brainteaser.

Here's the mazda B2300 in all its glory.	The exhaust bolt that had melted away let the header pipe drop enough to reduce backpressure, which caused the P0401 and let air in to confuse the O2 and ruin fuel trim. This patch job is still in place but will eventually be removed.

The F-150

With new vehicles costing as much or more than the house I built back in the mid-eighties, it’s a no-brainer that people are jumping through hoops to keep their older wheels rolling. I have no hard numbers on this, so shout me down if you disagree. Pickups tend to stay on the road longer than cars because cars don’t have the same “cool” factor and on the practical side, you can’t haul much in the back of a Buick Century or a Ford Taurus. A colleague of mine brought us his 1998 F-150 with an MIL illuminated, suddenly dismal fuel economy and a strange new noise. 

A year ago we had repaired a P0401 code on this same truck after he had attempted to replace the EGR valve on his own and had broken one of the valve’s seized retaining bolts, so rather than drilling out the broken bolt, we had simply robbed the throttle body goose neck off another 98 F-150 engine we had just yanked out of a truck like his, cleaned the EGR passages, installed the new EGR valve he had purchased, and got the gasses flowing again. Well, now his P0401 was back along with fuel trim numbers hovering near +20 on bank 2 (bank 1 stayed near zero), and we also had what sounded like an mild exhaust leak somewhere on the passenger side of the engine.

Applying some vacuum to the EGR valve by grounding the EGR Vacuum Regulator trigger wire, we heard the idle quality deteriorate and saw the voltage at the DPFE change from 0.6 to something like 3.5. While the DPFE should have gone a volt higher with EGR flowing, I was satisfied that the hands-on test exonerated the vacuum feed, the EVR, the EGR passages, the DPFE sensor and the silicone hoses.

Well, the end of that story was that the exhaust noise was the cause of both the P0401 and the high bank 2 fuel trims. One of the exhaust manifold header pipe studs had melted away with age and the header pipe had dropped a bit creating enough of an exhaust leak to reduce EGR flow because of lower backpressure at that point (the tube gets its feed from about an inch north of there) and to allow the O2 on that bank to get a good sniff of fresh air that skewed the fuel trim.

The owner needed the truck for the weekend, and it was the end of the day at the end of a week, so I grabbed an old 5/16 Allen wrench, some all thread, a 3/8 nut and the hourglass-shaped plug plate from a new A/C compressor and applied 10 minutes, the torch and a bit of brazing to build a temporary clamp with the agreement that we’d replace the quick-fix contraption I built by drilling out the dissolved bolt at a later date. That concludes story “related or not” No. 1. The sound, code and fuel trim were the condition, the exhaust leak turned out to be the cause, and fixing the exhaust leak turned out to be the correction.  These three concerns were obviously related.

With my homemade tool installed in place of the O2 sensor we got this reading. Rule of thumb is that there shouldn't be more than 1.5 psi of pressure in front of the catalyst.	It would seem that this catalyst would have driven exhaust pressure higher than it did, but this is what we saw when we cut the old cat our of its pipe.	This is the graphic of the Mazda's fuse panel superimposed on the schematic with the fuse and relay highlighted both ways.

The old Blazer

This second story is about a pain-in-the-fanny brake problem ‘88 Blazer that belongs to one of my guys – yeah, I know it’s old, but this won’t take long. He had lousy brakes, a leaking master cylinder and a hissing booster, so he bought a rebuilt booster and master cylinder assembly from his favorite parts store chain. He removed the cylinder from the booster, replaced the booster, then bench bled the reman cylinder and installed it to discover he still had a lousy pedal. We bled the brakes until we were blue in the face and even adjusted the rear brake shoe clearance, but that didn’t do anything at all for the pedal height, which felt passable with no vacuum at the booster, but the pedal went to the floor with the engine started.  Further, fluid would geyser from the larger rear chamber like Old Faithful with every brake pedal application if you pumped the pedal with the fill cover off. He got a replacement reman from the parts store and it did the same thing, but with a new problem — the brake line from the smaller (rear brake) chamber couldn’t be tightened enough not to seep fluid, and no amount of bleeding worked – that one performed just as poorly. Then we got a replacement master cylinder from a different parts store that looked and acted entirely different. The reservoir was even a different shape. With that one, we had good pedal and neither line seeped fluid. Condition – lousy brakes. Cause, lousy master cylinder – corrected!

The Envoy

This 2004 Envoy had a couple of unrelated problems, but it bears a short visit. The owner complained that the vehicle lacked power and that the seat belt on the passenger side didn’t work. The belt was hung up so that you couldn’t reel out any strap to buckle it, and that belt happened to be built into the seat, and the seat had to come out and be stripped nude to get to it. We ordered one from the GM dealer.

We did some basic checks on the low-power concern and wound up focusing on the catalyst. I have a Forward Looking Infrared (FLIR) camera, but I couldn’t categorically condemn the converter with the picture I took with it, so I had one of my guys remove the O2 sensor (which fought us tooth and nail to the point that we destroyed it getting it out of there) and then we screwed a homemade tool of mine in there. A year or so ago I had taken the 18mm plug out of a new catalytic converter’s O2 sensor hole, drilled it, tapped it and installed a brake bleeder for a hose connection. With the O2 removed and the hose of a plain old vacuum/pressure gauge installed, we read 5 psi of pressure upstream of the converter, ordered a Walker universal weld-in replacement, and the rest is history. The original catalyst was cracked and clogged to beat the band, and so that problem was solved.  Condition – low power; cause, clogged cat; correction – no-brainer.

In the meantime, the seat belt assembly we had ordered from the dealer came in and when we got the seat stripped down and unpackaged the new seat belt we discovered two crucial facts.

1. The replacement seat belt wasn’t the right one. Not even close.

2. A popsicle stick that had fallen into the seat was fouling the reel.

Condition, cause, correction. Simple!

This Walker weld-in replacement cat was just what the doctor ordered. It's tricky though—you can't just weld it in there without first bolting the exhaust in place and tacking it to make sure it's lined up properly. Just welding it in with reckless abandon creates a no-fit situation.		When we pulled fuse 25, the A/C clutch released, so we installed it and pulled the relay to find that the points on the relay were stuck. We measured 3.4 amps with the relay removed and a DVOM driving the electromagnet. The relay apparently just got tired and died.

The B2300 epic

In regards to our focus vehicle, the maintenance man who owns the Mazda pickup in question told me that as he drove, his A/C airflow would gradually decrease to the point that, while he could hear the fan, he had no air at the register. I asked if the air was going north into the defrost vents, and he promised to investigate and report that piece of data the next time he drove. At our next liaison, he reported that there was no airflow anywhere when the registers died.   

Let me pause here to say that he usually mentioned this concern in passing as he was making his rounds in the shop while I was preoccupied with other tasks, and without giving his concern too much thought I initially theorized that he had a problem with loose leaves in his evaporator case. We have that problem in these parts. Perhaps the leaves or trash would settle away from the evaporator when the truck was sitting fallow and then be picked up one or two at the time until the airflow was mostly blocked? That theory was really kind of weak, and I should have been thinking more clearly, but any time airflow goes away and the fan is still spinning, it’s a foregone that there’s something going on with the evaporator.

A week or so later he told me he was having to jump the little truck off in the mornings. He’s an industrial electrician (a good one) and he checked the battery voltage each time he had to jump the truck off; it was always in some state of discharge, usually below ten volts on his meter, and then one day I had him stop the truck long enough to have a look see at it myself. He parked the truck outside one of my service bays, and I dug my personal meter out of a desk drawer, set it on amps, and we connected it in series with one of the battery cables. I explained that we’d need to let it sit there with the meter connected for at least 30 minutes to let all the boxes charge up their capacitors and whatnot, and so we did.

When the appointed time had expired, I walked to the truck and still found 2 + amps flowing. He was passing by on his security patrol on the golf cart and stopped by to compare notes just as I was getting started. I explained that we’d need to start at the under hood fuse panel, and so he reached and took the cover off – and for a second, the amperage deflected to a lower reading, then returned to just over 2 amps.

We started removing the larger fuses while watching the meter, and finally worked our way down to fuse 25, which feeds the secondary side of the A/C clutch relay, and we heard the telltale “click” of the compressor clutch disengaging. I reinstalled the fuse and heard the “click” as A/C clutch snapped back in, and then removed the clutch relay to see and hear the same disengagement. After that it was as simple as moving the washer pump relay to that relay position and verifying that the clutch worked right.

While we were thus engaged, I had one of my guys removing the blower so we could look in the evaporator case for trash, but now we fully understood why his airflow was going away. If the compressor relay coil is de-energized on this one, the compressor is supposed to drop out, but with the relay contacts welded together, the compressor just kept on refrigerating regardless of the PCM’s command until the evaporator became a block of ice.

After the fact, it was abundantly clear that his symptoms were related. We just didn’t know how until the smoke cleared and the ice melted. Conditions: airflow and parasitic drain. Cause: stuck relay contacts.  Correction – obvious.  

Article Details

Fri, 11/06/2015 (All day)

Richard McCuistian

<p><span style="font-size: 11.8181819915771px;">Gathering data and sorting it out requires a sharp-minded clear thinker, and everybody who&rsquo;s in the know will agree that a really good troubleshooter in our field needs to be just a bit smarter than the average bear on a number of levels.</span></p>

I’ve encountered many a sweeping change in my 40 years of automotive experience, and I’ve heard complaints from both sides of the service aisle about why manufacturers think they have to keep changing things instead of leaving well enough alone. Well, as I used to tell the old timers, we could still be riding horses and rowing boats, I reckon. They complained about the move from contact points to electronic ignition, carburetors to fuel injection, and so on.  Granted, there are some elements of our vehicles that seem to have been changed for the sake of change. Modules now take requests from switches and energize loads through relays, and many of those relays are now being integrated into the modules instead of being individually replaceable, which makes repairs unnecessarily expensive. For one example among hundreds, the fuse panel/junction box on a 2006 Sonata costs about $700 and contains several integral relays. And then there are those eggshell fragile “smart” junction boxes. The only piece of 21st century technology on my 100,000-mile 2007 Ford Taurus is the smart junction box, and it holds the distinction of being the only part of the vehicle that has ever given me any trouble.

Some of these “smart” boxes have labels stating that the module has to be replaced if it’s dropped from more than 20 centimeters. Networking abounds, and not only within the vehicle’s perimeter; nowadays when you pull your late-model car into the garage it may ask to connect to your home’s WIFI, and just about everybody has heard about the very troubling experiment where a couple of hackers were able to drive that Jeep into the ditch after having hacked its internet connection and taken control away from the driver.

All that being said, these sweeping changes will keep on sweeping, but people are still driving older cars that pre-date these changes, and those cars still need fixing. The good thing about the moderately older cars is that a lot of technicians have left digital bread crumbs in iATN and Identifix pointing us in the right direction, and there are TSBs that provide short cuts to some solutions that might otherwise take hours to troubleshoot. Newer platforms and those that are sparsely represented in the market have fewer recorded repairs, and they may require the technician to plow some new ground. To be frank, we can discover that we’ve been dreadfully spoiled by the databases and find ourselves troubled and plowing new ground if we can’t find a silver bullet among the posts.

Handling help requests

I get quite a few emails through my website asking for advice, and I sometimes get phone calls from shop owners and family members that live in other states. I wish I could say I have all the answers, and I try to answer the emails quickly, but there are times when the person making the request doesn’t give enough information and there are other times when I simply don’t have an answer for them. Sometimes the help request is super sparse, like those doggone work orders I used to get when I was at the dealer where the service advisor put the words “Runs rough” on the repair line and the car would perform just fine when I drove it, and then I’d discover the owner was talking about a mild tire balance concern at a certain speed on a certain stretch of road.

Sometimes, however, a savvy vehicle owner will articulate his or her concern very well and emails will be exchanged that bear fruit. For one example among many, I had an email exchange that went this way, and it had a happy ending:

"My car has started to hum at certain speeds. It's an automatic, but when it's in fourth gear, it starts to hum. Do you know what this could be?" Joe asked.

"What make, model, and year car is it?" I replied.

"It’s a Mazda 6 sedan, 2005. It hums when I'm up to 40 or 4th gear,” Joe said.

"Does it change with throttle angle or vehicle speed (remaining in 4th)? I asked.

"Yes, if I go past 40 it will start to hum pretty loudly.” 

"If you swerve gently back and forth does the humming get quieter or stop? If so, it's probably a hub bearing." I wrote.

"You are amazing! I found it was the hub bearing. I went to a mechanic who tried to take advantage of me, and I was able to break down the symptoms and possible issue. He suddenly took me seriously.  Thanks again!” Joe said.        

This is the Camry, family dog, kid in the backgound, etc., parked in my son's driveway in Georgia.

I once heard somebody say that the MIL light is the most reliable part of his or her car—it always works. I wish I had a nickel for every car or truck I've seen with the MIL light hiding behind a family photo or piece of tape. I've actually known of older mechanics (years ago) that would purposefully render the light inoperative because they were tired of it turning on and turning up like a bad penny.

This is a rather familiar kind of exchange – more than a few people email me with car trouble before they even take the problem to a shop, because they’ve been burned before and they’re trying to insulate themselves against being fleeced by a misdiagnosis or an unnecessary upsell. And while we know that not every shop is prone to try and take advantage of people, just about everybody reading these words knows that there are too many shops out there that don’t repair the problem and leave customers frustrated and angry. The other side of the coin is that there are some customers who are treated right that sometimes leave shop owners just as frustrated and angry because we all know that the customer is not always right. Sometimes they’re dead wrong and just want something for nothing. The magic is in being objective enough to know the difference between when we’re wrong and when they’re wrong, and our bottom line can be a strong motivator, but our good name is worth more than just about anything else we own. Sometimes it’s best to bite the bullet and satisfy the customer, because they will talk trash about you if they believe you did them wrong, even if it’s a gray area.

A call for the calf rope

This story begins with a help request from my youngest son Luke, who lives six hours away, is married with kids, and works as a computer network specialist for a very large company. Vehicles aren’t his area of expertise, but he’s a quick study and never quits working on something until he gets it fixed. To begin with, his Camry’s water pump locked up and destroyed the timing belt, but the 2.2L belt engine is a free-spinner, and so he had a wrench-smart friend replace the water pump and timing belt, but when his friend was turning the engine through by hand to check for proper timing after replacing the belt, it would reach a lock point like the piston was making contact with something.

“I’m going to have to pull the head,” he told Luke, “apparently it has bent some valves.” My son remembered hearing me say that it was a free-spinning engine and so he put his friend on the phone with me.

“That engine doesn’t bend valves,” I told him. “You’ve got something on the head of a piston.”

“Well, in that case I need to pull the head anyway,” his friend replied, and I agreed. He did, and found some of that powdery carbon had broken loose and piled up of the head of a piston, and that’s what was stopping the engine when he was turning it by hand.

The head was re-worked, the crud was cleaned, the gaskets were scraped, the head was reinstalled, and the engine began to breathe fire again, but the MIL almost immediately illuminated and while there wasn’t any black smoke, the gas mileage was in toilet territory, which defeated the purpose of getting this 16-year-old Camry back on the road. A code P0125 was set (engine too cold for closed loop), and the data stream scan revealed engine temps south of 160, so Luke replaced the thermostat and cleared the code, which immediately returned. He called me and said everybody he was talking to in his neck of the woods – including his mechanic friend – said the new thermostat had to be at fault, and the engine was indeed running only slightly warmer than it had previously. I’ve personally had to install three thermostats to get one good one, so I agreed. I wasn’t there to look at the rest of the data stream, but this code needed to be addressed before anything else was done. He went through a couple more Chinese-made parts store thermostats and then paid $25 for a really good one from Toyota, and while the engine temp was now hovering just above 200 degrees, the code kept returning. Remember, all this back and forth was happening via phone calls and photos sent via text message.

Since we know this connector is H3, we can find the pinout in the shop manual, and using the schematics we can determine which pin(s) need to be our focus.	In this case, simply turning over the connector caused the brown E1 wire to disengage from the connector shell. This was the cause of the P0125, which usually means the engine is running too cold, but not on Toyotas of this vintage. A kissing cousin of the P0125 is the nearly as popular P0128 code.

At that point I decided to punch the Camry into Identifix and discovered something I hadn’t encountered before — that some Toyotas of that vintage would throw the P0125 if for ANY reason the engine didn’t drop into closed loop – and that the majority of posted fixes revolved around replacing the “A/F sensor.” Obviously, if the sensor never comes alive, closed loop is a faraway dream, even with a warm engine, but the Toyota’s algorithms weren’t flagging any kind of O2 code, thus the confusion. This information is also briefly stated in the Toyota shop manual.

The Identifix post we perused in detail says, "Check the heater resistance of the A/F ratio sensor. It should have between 0.8 and 1.4 ohms,” which is just peachy if you’re working on a California car, but this one is a federal emission standard vehicle (I researched this afterward), and so when we found 13 ohms heater resistance, a new sensor was purchased – and Luke’s digital multimeter indicated that the new sensor’s heater resistance was almost the same as the old one. Quite predictably, the code returned.

At this point I told Luke we needed to make sure voltage and current were available at the sensor. I like to take an old sensor, clip the connector off, and wire a small low impedance light bulb into the O2 heater circuit in place of the sensor. Yeah, I know that most automotive instructors are terrified of even a low impedance test light, but I raked that rule off the table the first time a digital meter told me a voltage lie and caused me a couple of hours of work. At any rate, there was no voltage at all being delivered at the O2 connector with the key on OR the engine running. Now we were getting somewhere.

When you think you know

As with any circuit, understanding this one is important. Like most heater circuits, this one is hard-wired to power and receives its ground from the PCM, which typically keeps a close check on how much amperage the sensor is drawing.  Let me also say here that in the late ‘90s, Toyota didn’t believe in putting circuit numbers or wire size tags on a schematic – all they put next to a wire is its color, and that can be annoying when you’re clicking from one schematic to the next looking for sources of voltage. The colorful wire trails and pin assignments are troublesome as well (see illustration).

With the connector in hand and my help, Luke identified the proper cavities at the harness connector, and we assayed to determine whether it was the ground or the power that was missing – as it turned out, one of the wires was broken right where it passes through the seal and goes into the connector to its terminal – but it was somewhat stealthy in the way it manifested itself. At first blush, a look at the place where the wires go into the connector seal looked just fine, but as the connector was rolled in his fingers, the broken wire pulled out, and we had hit pay dirt.

The brown wire on the schematic and in the photo is reference ground for the O2 sensor element, but has nothing to do with the heater. This broken wire was obviously the cause of the P0125 – since PCM is watching the voltage in relation to this ground and it wasn’t there, the O2 was flat as far as the PCM was concerned. Usually if you measure O2 voltage live on a groundless sensor you’ll see something that looks really high, like 2-3 volts, but the PCM won’t be able to see any voltage at all. And so Luke and his wrench-smart friend set about to make repairs – with butt connectors (face palm) and a pigtail they got from somewhere – the next thing that happened was a no-start, which brought another phone call, and I managed to vector them in to the right fuse, which turned out to be the fuse that feeds the EFI relay. With the replacement of that fuse, the no-start was handled, but the first time Luke drove the car to work the MIL returned, and when he got around to retrieving the DTC he discovered a P0135, which indicates that the O2 sensor heater is either pulling too much current or not enough.

This time he found a bad butt splice on the black/yellow wire that feeds the heater, thus the P0135. Once he got that straightened out, the MIL was gone and the gas mileage had returned.

It was a twisted path and everybody involved came out a little smarter on the other end.  I just wish we could get rid of those butt connectors.   

The draftsman who drew the color-wird schematic moved the pins around on the empty white box representation of the sensor to minimize wire-crossing on his drawing, but the innards of the sensor are revealed on the O2 specific schematic in that part of the shop manual.	This was the blown fuse that killed the car after all the butt-connecting was done.	I'm a solder and heat-shrink man and I teach my students to fix wires that way. Butt when you're working in the driveway on your own car and you do computer networking for a living, you call this an "improper termination point" and you fix it the best way you know how, which, as we see here, turned out to be less than reliable the first time around. The car is running without an MIL, but I hate butt connectors and always have.

Article Details

Thu, 12/10/2015 (All day)

Richard McCuistian

<p>When the MIL keeps coming back.</p>

Whenever somebody wants us to apply our expertise to give them peace of mind, it would be nice if we were able to offer a 100 percent guarantee, but no matter how good we think we are, time and chance can always get the upper hand. About 30 years ago, a relative of mine brought me his early 80s VW Rabbit for an inspection – he was taking it on a fairly long trip, and so I gave it the once over. I did most all of the maintenance on this vehicle, so I had carnal knowledge of the car, and I could find nothing wrong with it on my inspection.

While he was on his trip, the alternator died, and a shop down in Florida charged him $300 to diagnose and replace it, which was highway robbery in those days. When he returned from the trip, he chastised me because I didn’t tell him the alternator was going to fail. Yeah, I know. I rolled my eyes too. I suppose if I had replaced the alternator, the starter, the battery, and who knows what all else, I could have averted the breakdown, but at what cost?

I remember my dad telling me about a very demanding elderly widow who came to his shop and told him she wanted him to do a comprehensive inspection of her vehicle every month and she would pay him generously each time. She then told him that if he agreed, anything that ever went wrong with her car would be 100 percent his fault and she would expect it to be repaired free of charge. He refused to even touch her car, and sent her on her way in search of a sucker, which he wasn’t. Gotta love those folks who want us to “own” all of their future problems, right?

This Jeep is the customer's primary ride, and she had been putting up with the supposed "brake pulsation" for quite a while.

Recently, a young woman who is just beginning her adult life brought a vehicle to me so I could “look it over” to see what I thought of it before she bought it. I’m always kind of nervous in situations like this, because a used car is, after all, a used car, and we all know that no inspection we can do for free goes deep enough to give a 100 percent guarantee of anything.

In this case, I checked all the fluid levels, perused it above and below for leaks of any kind, checked the age, pressure and condition of the tires, examined brakes and suspension parts, all of which looked fine, but I had to kill a large and healthy brown widow spider that had webbed the area just inside the right rear wheel and was waiting for a kill. There wasn’t much rust on the non-coated undercar components, so this car must have spent its life away from the coast and far enough south to avoid salt. I was most concerned about the timing belt, because that 2.7L isn’t a free-spinning engine, and with just over 100K on the clock, I decided to remove the upper part of the cover to have a look. Yeah, I know it’s usually difficult to look at a timing belt and say for sure how old it is, but this one had bright white part numbers on it and there was even a sticker on the shock tower proudly announcing the recent mileage at which the timing belt had been replaced. That put my timing belt fears to rest, and after checking for obvious electrical problems, I rounded out my inspection with a rubber stamp. The car seemed fine as far as I could tell

A shop in town had replaced the park brake cables on this Miata, but the park brakes wouldn't stay adjusted. What the cable replacer didn't know was that this adjustment screw (normally hidden by a cover bolt) would adjust the park brakes the right way. We made the adjustment, but I told the Miata owner that we might have to adjust it again if the brakes got loose again.

She thanked me for the free inspection, bought the car, and drove it for about two weeks, and then one day I was at lunch when she called to tell me that the engine had stopped running, and that she had coasted off to the side of the road. As I questioned her about it over the phone, she said the engine would spin but wouldn’t start. I told her we’d get the car to the shop after lunch and have a look at it.

Her folks decided to take it to a shop they liked to use (I do not know this shop or the man who runs it), and after changing a couple of parts and charging them a Ben Franklin or two for those fruitless attempts, he pulled the entire timing cover and said pieces of an old timing belt were trapped in there and had caused damage to the wiring. Then a couple of days later she told me he had called to say that the engine was locked up and he wanted eleven more Ben Franklins to replace it.

Busy times

My people are predictably happy when we have plenty of work. This time around it’s transmissions, brakes and steering/suspension, and we’ve had quite a lot of it. I had a couple of guys doing a go-through on a 4L60E as a bench job just for the experience of tearing it down and reassembling it, then I surprised them by having them stuff it in a 2001 Chevy trainer truck we have on hand just to see if it’d pull. It didn’t, and all the pressures were low. They ran some tests before reinstalling the original transmission with the notion that they’d tear down and re-evaluate the one that didn’t work. We also had a 2004 Dodge Stratus with an incorrect gear ratio in 3^rd gear code, and that one’s still under way – it performed okay on the test drive except for a chatter on the 1-2 shift, so it’s coming back out to tear down and re-check for proper assembly.

The Durango's headlamp wasn't as straightforward as the owner had imaginied it would be. The module was sending voltage out to the light intermittently—it had an internal fault. We ordered a replacement module from Ebay, but there is no 100% guarantee it will be a good one.

We’ve done enough brake jobs over the past few weeks to fill my “old brake pads” bucket to capacity, and wheel alignments have been numerous and instructive. We’ve replaced multiple sets of ball joints, steering racks, pumps, leaking lines and even a front differential chunk. We had a park brake problem on a ‘91 cream puff Miata – the brake cables had been replaced by a shop in another town, but the park brakes kept getting loose, so we adjusted them the right way. We had the red ’71 Eldorado convertible back in the shop with a steering pull and a pop noise when backing up that turned out to be worn idler arm.

Then there was the wild card – a Dodge Durango that was shifting erratically and had one headlight that was going off at random – and it was off most of the time. The customer brought us a headlight connector, because when he replaced the bulb the problem remained. A simple transmission service took care of the erratic shift, and the headlight problem turned out to be in the BCM, which is totally responsible for the headlamps. I found him a replacement module on eBay.

The Jeep “brake” problem

Our title vehicle came in for an alignment and what the driver described as a brake pulsation that “keeps pulsating even after I let off the brakes.” That sounded kind of anomalous, but that’s how I wrote it up. She left it with us, and later that morning I grabbed one of my guys and we launched our diagnosis.

The first thing I noticed as we started it in the service bay was a really high idle. As a matter of fact, the idle was so high I wondered if the foot feed was fouled by a wrinkled up floor mat (I’ve seen that more than once). I sent my guy to fetch a scan tool, and we retrieved the DTCs and found only a P0455 – no surprise on one of these – and then proceeded to hack into the live data, where we noticed right away that the reported throttle position sensor voltage was a lot higher than the baseline minimum. That would explain the high idle.

The only DTC we got was caused by a split hose—the live data showed (at idle) this TPS voltage. Note the difference between actual voltage and the benchmark minimum.

When the PCM wakes up on most platforms, it pegs the TPS voltage at key on and tags that number as the baseline for closed throttle. On some platforms, that number is stored as a part of the adaptive memory. But on the ones that re-read it at every key on, any voltage higher than the baseline after initial start is considered part throttle for the rest of that drive cycle, and at part throttle, the IAC steps will be high, poised for dashpot function (slow return to idle so as not to stall). As long as the TPS is considered to be at part throttle, the IAC will remain that way, which makes for a fast idle on non-electronic throttle body systems, even with the throttle plate closed.

After a moment or two, and a tap on the throttle (which is almost reflexive when the idle is high like this), the idle more or less normalized, and we backed out of the shop. When we had cleared the runway, wheels up and locked, we reached cruising speed on the four lane and slowed at the first turnaround to feel the brakes. We didn’t feel a brake pulsation, but we did feel the engine laboring as the vehicle slowed – the transmission was in high gear and continued to quiver and labor – even after we let off the brake – before dropping back into low gear when we were almost stopped.

I had felt this kind of thing before on other vehicles – GM platforms, mostly – when the TCC solenoid was sticking and keeping the converter locked while the vehicle was coming to a stop. In one of those cases we did a transmission service and dumped some Sea Foam trans tune in there – and fixed that one.  In another case, we did the same thing to a 2008 Impala that was reportedly having screwball transmission issues and it fixed that one too. Sometimes the quick and easy is the smart way. Sometimes the quick way is the only way when there isn’t time for anything else.

This 1995 Honda Accord's alternator was replaced back in July for a non-charging condition. It showed up again in October for draining the battery overnight. We traced a 5-amp drain to the new alternator and ran a diode test with a cheap meter (it shouldn't read both ways). Another replacement alternator took care of the draw. We had a warranty, but no 100% guarantee that she wouldn't have to jump it off again at some later date.

In this case, with the TPS reading like it was, I reasoned that the controller might be confused enough by the faux part throttle reading to delay the downshifts, and so we sold the Jeep driver on the notion of planting a new TPS on the throttle body just to see what happened – I was convinced that it needed that anyway, and it’d be an easy beginning.

Not so easy

We obtained a replacement part from the parts store and my guy set about to remove the old one and install the new one. Well, he tried to remove the old one, anyway. He got the top screw out but couldn’t move the bottom one. We all know these screws have thread locker on them and can be tough sometimes. GM Instructor Ellen Smith mentioned this annoyance in the CCC school I attended in 1981, suggesting the use of a soldering iron on the stubborn ones. We initially tried that strategy, but this one was ridiculously tough and destroyed two Torx bits, so we removed the throttle body and carefully mounted it in a vise. Nothing would move it, not even a good pair of Vise Grips. Sometimes even the easiest job can turn into a “monsta,” and this was an extremely defiant little fastener. We heated the boss with a bottle torch and continued to tighten the Vise Grips to the sides of that domed screw head, but it still wouldn’t turn.  We then ground the head off with an abrasive cutter and removed the sensor to expose the screw shaft in hopes of getting a better grip, but it still wouldn’t move – it was one with the throttle body. This was getting stupid.

Back to the Jeep—this little TPS scew was surprisingly tough to get out. Early on, a pocket lighter had been used to heat the boss, then a bottle torch, and finally, a heat gun melted the thread locking compound enough so we could rock the cadaver of this bolt back and forth and finally get it out of its hole. The TPS took care of the high idle and the transmission's delayed downshift.

Finally, I put away the bottle torch and hit the boss with a heat gun on high for about two minutes while applying Herculean pressure with the Vise Grips, and the shaft of that terribly stubborn screw finally began to turn. It amazed me to no end that the heat gun did what a blue flame wouldn’t.

With the new TP sensor installed and the throttle body re-mounted, we re-drove the car, didn’t feel anything untoward, and turned it back over to the driver. A week later she came back in for an alignment and reported that her perceived “brake pulsation” was gone. In a word, what she misidentified as a brake pulsation, we identified as an extremely late downshift, and our decision to treat the high idle/TPS problem turned out to be a surgical repair, and it felt good to get this one right the first time. And while we sometimes stumble around looking for the right fix, sensible decisions and surgical repairs are the benchmark of a true professional, but in our better moments, we all know there is no such thing as a 100 percent guarantee. This Jeep transmission fault may yet darken our door again. 

Finally, we had to work on the spark plug threads in a 6.8L van, and we had air blowing into the throttle body with the intake valve open to keep the tap cuttings from falling into the cylinder. Our problem was that, with the plug at the bottom of that deep well, we didn't know if the spark plug was seating after we fixed the threads with a tap. This is how we go our 100% guarantee that the seat was making contact. Prussian Blue is a wonderful thing to have on hand for this king of thing.

Article Details

Mon, 01/04/2016 (All day)

Richard McCuistian

<p><span style="font-size: 11.8181819915771px;">Whenever somebody wants us to apply our expertise to give them peace of mind, it would be nice if we were able to offer a 100 percent guarantee, but no matter how good we think we are, time and chance can always get the upper hand.&nbsp;</span></p>

<p>Richard McCuistian, Motor Age Garage, service repair, technical, Grand Cherokee,</p>

Richard McCuistian, a longtime Motor Age contributor with eleven ASE certifications (A1-A8, Light Vehicle Diesel, L1 Advanced Level Engine Performance, and G1), recently received recognition for his 25^th anniversary of being ASE certified. In honor of this prestigious milestone, we asked Richard to reflect on his expansive career in the service repair industry, including his passion for fixing vehicles, biggest challenges, and advice for newcomers to the industry.

Longtime Motor Age contributor Richard McCuistian holds his award for being ASE certified for over 25 years.

Motor Age:What has driven you throughout your career?

Richard McCuistian: My dad owned a shop, and from the time I was about four years old, I’ve always been drawn to grease, steel, sparks, switches, gears and bearings, hand cleaner, colorful cardboard boxes with new parts in them, and all the rest of it. I love using tools and fixing and maintaining vehicles, especially when the light bulb pops on over my head and I make the connection between the data and the fix. I like being the guy in a uniform who knows what to do when most others don’t. 

And most of all, nowadays, I love passing what I know along to the younger generation. We need new blood in this industry now more than ever, and I like being a part of that process.

Motor Age: What has been the biggest challenge you’ve faced throughout your career?

McCuistian: Like most people my age who started out forty years ago when electronic ignition was brand new and so many ignition systems were points-and-condenser, my biggest challenge throughout the years has been staying abreast of changing technologies as electronics have taken root in virtually every part of the vehicle. I spent most of my career at dealerships and got really great training there.

Now I’m teaching, so I have to make sure I stay up to date on what’s going on with the more common makes and models that populate the area where my trainees will be wrenching.

Motor Age: What is the most important advice to pass on to someone who is new to the service repair industry?

McCuistian: To begin with, you WILL earn what you get paid in this industry. After your foundational training (and it’s good to get that first), realize that speed and accuracy will be the engine and the transmission of your career. In order to get P.A.I.D., you have to exhibit Performance, a good Attitude, great Integrity, and bulletproof Dependability (hence the acronym). Once you’ve developed your troubleshooting and mechanical skills to the point that you work quickly and with accuracy, don’t think your skill level gives you a license to be a jerk. There are a lot of guys and gals out there who are better and faster than you are.

If you really want your knowledge to explode, always be willing to share what you know with others in the field. I learned early on that whenever you take the time to explain something to somebody else, you understand it even better yourself.

Secondly, realize that there isn’t a silver bullet for every problem. You have to be tough, and you have to be smart. You need to be ready to go where nobody else has gone before on a job and find the problem on your own when diagnostic tools and software don’t have the answer.

Motor Age: Why is training and ASE certification important to you?

McCuistian: Without training, you’re flying blind. Without ASE certification, you have no real credentials to show, and credentialing tells prospective employers that you’re serious about your career choice. I would not have been employable as an NATEF program instructor without ASE certifications. Further, some shops won’t even hire a technician that isn’t ASE certified. ASE certification doesn’t in and of itself mean you’re a super-wrencher, but you will command more pay as a capable and productive ASE certified student.

Richard, thank you for sharing your expertise, experience, and wisdom with Motor Age over the years and for your unceasing dedication to the service repair industry!

Article Details

Mon, 12/14/2015 (All day)

Chelsea Frey

<p>Richard McCuistian, a longtime Motor Age&nbsp;contributor with eleven ASE certifications (A1-A8, Light Vehicle Diesel, L1 Advanced Level Engine Performance, and G1), recently received recognition for his 25^th&nbsp;anniversary of being ASE certified.</p>

In my shop, it seems like we get hit pretty regularly with the ones that have been parked somewhere. A colleague of mine called me a couple of years back about a 1973 VW Beetle she had driven in high school. It was sitting in a barn on her property and she as all excited about getting it going again, because, while old Beetles used to be the cheapest car around for somebody who couldn’t do better, some folks consider them are really cool nowadays. Well, they’re not as cool as some people think they are, and to be honest, there are more than a few for sale around here that are over-priced. I probably owned a dozen VW bugs (and a Ghia or two) before I turned eighteen because my dad had a VW shop, and to me, a VW bug was something I drove when I couldn’t do any better. That being said, I had a lot of fun power sliding around dirt road curves on those back-heavy bugs and plowing through waist-deep mud bogs that would stick a four-wheel drive pickup, and dad taught me how to make a plain old VW bug run like a Porsche on a shoestring budget.

It’s no wonder they wanted this one back on the road — they even cleaned it up before they brought it to us.

Anyway, this lady I knew thought she and her husband were going to roll that old bug out of the barn, put a battery in it, run the field mice out of the glove compartment, fire it up, and drive it to the courthouse wearing a big smile. And while we’ve all heard stories of people who, with minimal effort, recovered a ride that had been sitting for years, we all know that isn’t usually the case, and I warned her that the moving parts on that barned bug would most likely be rusted together.

In spite of the fact that the bug had been parked out of the weather, she later reported to me that I was right on target. Everything except the steering box was either locked up or so stiff it could barely be moved. She was intelligent enough to shelve that project and move on. The bug wasn’t cool enough to merit the weeks or months of spare-time and rusty love it would take to get it back on the road.

I once purchased and drove a 1970 model Ford pickup from a guy who had found it sitting in a barn. He told me he had put a battery in it, got a tag for it, and drove it for a few months before he sold it to me. And I later sold it to somebody else, but it ran well, even though it looked rusty and junky.

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Back in ’72, I was at a friend’s house when his dad and his brother dragged a 1953 Ford out of his late grandmother’s garage.  This thing was covered with dust and had been sitting in there for years. Granted, the car was only 19 years old – equivalent to a ’98 model in today’s world, but we hooked a rope to the front of that old bomb, put the column-shifter in second, and dragged it down the dirt road with a pickup. It fired up and ran like brand new. My friend had just turned sixteen and thought he was looking at his first car. Wrong. His parents literally gave that car away to a relative, who sold it for junk. Go figure.

Rats and a three valve

Then there are the ones that come to us having been driven every day, but with critter damage. Rats, squirrels, and dogs can do ruinous things to a vehicle. One of my guys works at the local Ford dealer and he found critter damage on a brand new vehicle with less than five miles on the odometer – it hadn’t even been through pre-delivery, but the knock sensor harness was chewed in two under the intake manifold. I’ve found bird nests with eggs in them under the hood on a car that was driven every day, dead cats in the radiator shroud (along with a busted and out-of-balance fan), and one F150 with so much dog-tooth damage that a very thick wire harness was chewed completely in two and some of the EVAP hoses were destroyed as well. At the dealer, that was a thousand-dollar repair, and it was the work of the neighbor’s hound. If that wasn’t bad enough, the same dog got under there a few days after I repaired it and did even more damage.

This is a picture of rat damage that kept reoccurring on an Explorer we worked on a while back. It got so bad that the lady put rat poison under the hood. It got the rats, but not before they got the wires one more time.

Anybody who has done much automotive electrical work has seen animal damage to wire harnesses and hoses. This truck came to us with the “barned for years” syndrome and was also reported to have rat damage as well. It started, but all it would do was idle, and it didn’t even do that very well.

There was a “Reduced Engine Power” message displayed in the cluster, but the rat damage we found on our first pass was minimal – the only thing the rat had chewed was the knock sensor wiring. So why wouldn’t it idle? I put a guy to work figuring it out.

The three valve

In the meantime, a 2007 Expedition came wheeling in with some pretty serious misfire issues. The owner wanted the fuel pump replaced before we did anything else, and so we did that at his request, but to no avail. His reasoning was more or less like mine — we had replaced the spark plugs on this Expedition only a couple of years ago, so I was surprised to find that it needed another set, those snouty carbon-stickers are always fun. He had driven it many a mile since our first replacement. My instructions to the guy who drew that job was to get the engine good and hot and jerk the spark plugs out with an impact wrench. He did, and we got all eight plugs on the bench in no time at all. Bringing them out quickly tends to break that annoying carbon bond and works a lot better than anything else we’ve tried… and we found early on that we have absolutely nothing to lose using this method.

After we got done with the spark plugs, one of my guys was doing an inspection of the rest of the vehicle and found a leaking strut on the right rear. What was odd was that it looked like it had just started leaking while it was sitting there. Gotta love those. The owner is fixed-income retired, so he only wanted that one shock replaced.

The Trailblazer

Some jobs seem pretty simple – a 2004 Trailblazer came in with a leaky radiator and a rattling noise that turned out to be bad water pump bearings, and in the process of replacing that pump, an overzealous youngster broke one of those six-millimeter water pump bolts off in the timing cover using a 3/8 air ratchet to tighten them. Live and learn. With the radiator removed and the grille out of the way, I put him to work drilling it out (center punched first) and even with another guy helping him, all they could do was complain that the drill bits I provided weren’t getting the job done.

I cautioned them about spinning the drill bit too fast – and an air drill likes to do that – so they were relegated to using an old Makita electric 3/8 drill, but in true form, they cried and walked away. I got a stool and sat down with the same drill and the same bit they had been using and drilled far enough into what was left of that bolt so that I could snag it with a screw extractor and literally bring it out of there with my fingers. They swore I had found a better bit, but I used the same one they did. They just needed more grit.

Discovery on the reduced power

Back to the Silverado, my guy discovered that the Throttle Control Module was offline – no wonder the throttle wouldn’t move! I pondered the very existence of this module early on. Presumably, Ford adopted the faster processing Black Oak PCM before they went ETC, lagging a few years behind GM, who elected to keep the same Delphi unit and add another smart box to bring the necessary reaction time for drive-by wire. This little box takes input from the three redundant Accelerator Pedal sensors and drives the throttle plate, all the while watching the blade’s position via a redundant pair of pots. It talks to the PCM via the painfully slow UART link.

This new fuse that feeds the ETC module did a serious flash-bulb as soon as the key was switched on. (Try catching this image with your camera!)

Well, the ETC/ECM fuse was blown to smithereens in the junction box, which would explain why the ETC module was down, but when we inserted a new fuse and powered back up, the new fuse we had installed flash-bulbed. Could this be the result of rat damage we had missed on our first pass?  It seemed possible.

The ETC module is mounted between the brake booster and the fender (the yellow paint-numbers are on the salvage yard part that fixed it). We first removed the cover from the unit looking for something obvious — didn’t see anything, then we checked the pins for proper power and ground and found nothing out of the ordinary.

Schematic-reading showed one power and one ground, both of them leading to the C1 connector. Pin 15 is hard-wired to ground and pin 7 receives power from the fuse, which would immediately vaporize with the module plugged in, but would remain un-blown with the module disconnected. We found another grounded pin in the number 6 cavity, which, as it turns out, is connected to the high mount stop lamp for the purpose of canceling the cruise.  Checking pin 6 in C1 showed a ground that would go away when the brake pedal was depressed – there were no other grounds leading to the connector, and since the short went away with the box unplugged, the box had to be internally shorted. Why that happened while the truck was barned is something of a mystery.

As the schematic shows, pin 15 is ground, and pin 7 is ignition voltage. It was a simple matter to eliminate harness concerns.

I dropped by a salvage yard on the way home and snagged a used replacement module for thirty bucks. That solved the Reduced Power message and the non-responsive throttle issue, but the truck still ran awful, and we intended to find out why. Perhaps some hidden rat damage awaited after all.

As it turned out, we had a misfire on cylinder six, and a set of spark plugs didn’t change a doggone thing. The cranking compression wasn’t as strong as we would have liked on any hole; every cylinder on that 4.8L was bouncing around 120, but the non-firing one wasn’t any worse than the rest, and it never hit a lick at any speed when the engine was running. Swapping coils didn’t move the misfire – it remained on cylinder 6, and an intake smoke test revealed nothing in the way of an intake leak.

We thought of doing a running compression test but figured we’d try one more thing before we did that. It was time to do an injector flow comparison.

Using the OTC’s handy $100 Electronic Fuel Injector tester, we watched the fuel pressure on each injector during 500 1 millisecond pulses and found that the number six injector was flowing no fuel at all. Eighty dollars later the Silverado was idling and driving smoothly. The rats weren’t as much of a problem as we had originally figured they would be. They only chewed two wires on this one.

Finally, the #6 misfire had to be addressed (see top screen), and the OTC injector tester fingered the problem handily — the #6 injector was clicking normally, but not delivering fuel. After it was replaced, the misfire was gone.

Article Details

Tue, 11/29/2016 (All day)

Richard McCuistian

<p>In my shop, it seems like we get hit pretty regularly with the ones that have been parked somewhere.</p>

<p>misfire, ETC/ECM, rats</p>

Those of us who have attended manufacturer schools know full well how important the progression of a repair goes. First, the concern must be verified (if possible). The freeze frame data helps in that regard with drivability problems, because that snapshot provides what Chrysler used to call a “similar conditions window.” But then there are those problems a scan tool can’t detect, but our ears and eyeballs can. Spraying or dripping fluid leaks. Engine noises from inside and outside; whining alternators and power steering pumps; rattling or rumbling A/C compressors. Those are easy to verify, but some of them can be difficult to pinpoint.

Back in 1977 I was working at a small independent shop for a guy named Ed Davis. That shop had a concrete floor, but no lifts, and it looked like a big barn, but it was in a good location. One day a ’70 model Ford pickup came driving in the door, and it sounded for all the world like something major in the engine was about to come undone. I stood there thinking we had a major overhaul on our hands, but Ed had the owner switch the engine off, and then he took his pocketknife and cut both belts off. I noticed that one of the belts was gapped and had chunks missing, but so what? That noise was nasty – surely there was metal on metal hammering somewhere! But when the owner restarted the truck without the belts, it sounded so smooth and quiet that I absolutely couldn’t believe my ears. A new set of belts fixed that one. Since then, I’ve been smacked around a few times by one problem either imitating another or cloaking one. 

This is a nice truck — well worth the cost of an engine.

The Titan

The subject of today’s article — a 2005 Nissan Titan with 157,647 miles — hadn’t been driven for a while because the owner was certain that the engine was destroyed, and she wanted us to listen to it. She said her husband had driven it until the oil light came on and kept driving. That sounded serious, but we figured we’d evaluate it anyway. She left the truck one night after we were closed and gone and we looked at it the next morning. We initially noticed two things. First, before we even started the engine, we found that the oil wasn’t touching the stick, but it only took three quarts to put it on full, so it wasn’t low enough for engine damage, and she didn’t mention having added any oil.   

When we started the engine, it was rattling to beat the band in the bell housing area and leaking oil from the rear main so fast that it made a puddle nearly two feet in diameter within three minutes. Seldom do we see a pressure-driven leak that bad this side of a double-gasketed oil filter.

I have seen a lot of cracked flywheels, but this one took the cake for having been driven many a mile until it began radiating cracks from the bolt circle.

The noise sounded suspiciously like a cracked flywheel, but we didn’t hear anything else – that being said, how long do you want to let an engine run when it’s bleeding to death, and who could hear anything over that nasty rattling in the bell housing anyway? It was telegraphing all over the place. I called and suggested that she let us jerk the transmission out for some exploratory surgery, and she agreed. What we found was a very seriously cracked flywheel. Not only was it cracked around the bolt circle, it had cracks radiating toward the ring gear. This was a big noisemaker. A new flywheel from Nissan is only a little more than a hundred bucks, and we got her to agree to the flywheel and a rear main seal. We had also drained the transmission oil (which was kind of black), and she’d get the new red stuff too. This transmission has a metal screen that can be cleaned and reinstalled. Justin steam-cleaned the muddy transmission and the other parts in preparation for the reassembly, but the flywheel wouldn’t be in for a couple of days.

Altima engine swap   

About that time, we drew an engine swap job on a 2005 Altima that came in rattling like a diamondback, and the owner was savvy enough to have a replacement engine dropped off right after the car rolled in. Externally, the replacement mill was rusty on the steel and chalky on the aluminum - it looked like it had been sitting somewhere damp, but it turned easily with the breaker bar and there was no sludge we could see in the oil splash area through the filler cap hole, so we didn’t even yank the valve cover. It did get a rear main seal just for grins. I considered transferring the catalyst heat shield from the original engine, but those little bolts will usually snap when you try to remove them, so I left it be.

With these two grounds swinging, the Nissan would just sit there and spin, which isn’t particularly surprising. What’s worse is when the guilty ground is buried somewhere out of sight.

With everything disconnected and the powertrain sitting on the OTC lift, we decided to take the Autel scope camera and the MaxiSys we got from AE tools to have a look in the upstream O2 sensor hole at the brick, where we found at least part of the reason for the engine failure, and it’s a fairly common occurrence on these little rascals. That potential source of damage tends to be cloaked if you don’t look here. The catalyst on the bad motor looked like Bryce Canyon Utah on a moonlit night when we took our snapshot, and some of that brick dust must have made it through the remaining comb, into the EGR system, and back into the chambers. The early Ford SHO Taurus engines tended to have that problem too. Fortunately, the replacement engine’s cat had a nice healthy looking light-off honeycomb.

This was actually kind of funny – a guy down the hill who primarily does diesel nuts-and-bolts work made this connection and couldn’t figure out why it wouldn’t charge. The alternator was checked and found to be fine.

And every Altima veteran knows it’s a good idea to shove new cam and crank sensors in the used replacement engine, but we didn’t (why I still don’t know), and this time we got lucky, but at first, we didn’t think so. The replacement engine spun without fire and even showed moderate activity at the COP coils with the PICO wand, but then he found two small ground wires on the upper part of the timing cover he had left swinging, and when we got those in place we had fire in the holes, but after a few test drives we found that it would sometimes default to idle and throw TP sensor codes – it would need a throttle body – we had used the car’s original one when we sewed it up, because the on that came with the replacement engine had fallen prey to the elements and risking that one would be a bad bet. Even with a customer-supplied engine, that job wasn’t cheap at the end of the day, but today it’s back on the road.

The catalyst on the Altima was a nasty mess, and this isn’t uncommon on those vehicles. Fortunately, the replacement engine’s cat looked healthy, but a bolt-on replacement runs about $350 or so if needed.

The frozen Focus

The 2010 Focus belongs to a colleague, and her complaint was that she’d lose her air conditioning after driving awhile. One of the first things we noticed was that the suction line would become coated with ice. This was a freezer and we needed to know why. The evaporator thermistor likes to die and prevent A/C engagement on these Fusions, but could it possibly fail the other way? We had popped one in there last year, and she didn’t seem to have much trouble after that, but this past autumn the problem returned, and we broke out the IDS to see what we could see on the PID list. Measured with a thermometer, the register temperature would drop into the low twenties with the evaporator temperature reading hovering just below fifty degrees. What the heck was this all about?

The freezing evaporator was apparently blocking the airflow across the thermistor on this Fusion – it’s not in the heat exchanger like they used to be, and that created the confusion.

Let me go on record by saying that I absolutely love Identifix and wouldn’t be without it, but in this case, the I-fixers weren’t much help. A/C problems abound on Ford Fusions and it’s easy to get bogged down wading through all the posts – I put in a hotline request and the guy suggested installing a resistor in series with that NTC thermistor – higher resistance translates to a lower measured temperature. A very competent Ford tech I know suggested the same thing. Had it been done successfully before? I had no idea.

With everything sitting fallow and the control box out of the loop, the thermistor measured the right resistance for ambient temps. And while I could see the hotline guy’s logic I couldn’t figure out why it’d be necessary to add a component like that to a system that wasn’t built with it. Of course, there have been times in my career when I did stuff like that for troubleshooting purposes, and so that’s what I did this time, but nothing seemed to change. In the meantime, we also noticed that the blower was come-and-go and we had to replace the controller and its connector to take care of that problem – that’s another common malady on more than a few vehicles we saw last summer.

The Discharge sensor was what we found ourselves focusing on, but actually the easy-to-change pressure transducer was at fault – it stopped the freezing problem for good.

While we were fighting the Focus, a 2006 Pontiac G6 came in with a charging system that wouldn’t work. Well, as it turned out, somebody had worked on that one in the starter area and had connected the fuse-linked alternator charge wire to the solenoid post that fed the starter motor where nothing is supposed to be – the charge current from the alternator was never making it to the battery – it was apparently just slowly spinning the starter motor as the car was driven. That one was easy to find because there was no B+ measured at the big alternator terminal. It looked like somebody had put the charge wire on the terminal that was easiest to get to. Rookies do that sometimes.

This is the part number for the transducer on a 2010 Fusion in case you run into one of these.

My breakthrough on the Focus freezer came when Jimmie, one of my superstars at a nearby Ford dealer, ran into the same problem on a Fusion he was working on. After replacing that $20 thermistor and his Fusion still freezing up, he decided that the A/C pressure transducer was at fault (I had never seen this), and while he was ordering one for the car he was working on, I had him snag one for me. And since we changed out that $125 transducer our Fusion has had normal A/C. The part is easy to change. This cloak came from the fact that the actual temperature of the evaporator case plenum was skewed because the evaporator was freezing up and blocking airflow – rather than measuring the actual evaporator temperature the old fashioned way, the thermistor is measuring that open area, and for some reason it doesn’t read the temperature of the air that’s exiting the registers, thus this problem was cloaked by design, albeit not purposely. The IDS PID in this case wasn’t particularly friendly, nor was it helpful. One way or another, this one snowed us for a while.

Clash of the Titan

The flywheel came in for the Titan, and with the oil leak fixed and the transmission re-stabbed, it was the end of a long day. We started the engine and it didn’t leak oil and ran quietly, but we didn’t warm it up, nor did we test drive it that day. That would happen the next day, and when I spoke to the lady on the phone, I even told her that the jury was still out but that it looked like we had maybe dodged a bullet, but I told her I’d know more on the morrow. And I did.

Yeah, we should have checked this first. It was a bad call — and all mine — to go after that flywheel noise and that geyser of an oil leak. We never stop learning, it seems.

The bullet wasn’t dodged. When we started the engine the next day to test drive it, we heard a tattletale knock as soon as we dropped it in gear – and it wasn’t a good sound. Apparently, it had gone lower on oil than we had presumed, to the severe detriment of some bearings. At that point we pulled the sump pan to find two things. We found a partially clogged oil screen and slivers of engine life forces swimming in the sump. It wasn’t a good feeling, but the lady who owned the truck was surprisingly understanding – the flywheel had indeed needed replacing, but a replacement engine very probably would come with one anyway, and that 2010 truck is worth an engine. I even found her one for a good price, but she decided to put off the repair until she could feather out financially. They drove the truck away with the knock, and from what she told me, we’ll see her again when she gets an engine. It was a heck of a lot quieter and there were no oil leaks, but it still felt like we had dropped the ball – and I guess we did.

Conclusions

I was lamenting the experience with that Titan to my advisory committee, and several of them said they had experienced the same kind of pitfall – one serious problem cloaks another one to the point that the first fix isn’t the final one, and some customers are more understanding than others. And I don’t like this any more than the customer does. With 20/20 hindsight, I realized that we should have pulled the sump pan before we went after that flywheel, because it would have been easy to do, and the bad call was all mine. I suppose the vibrations from the flywheel coupled with that hard rear main seal must have been the perfect formula for making a pint-a-mile oil leak, especially with the bearing(s) hammered out. Well at least we got that oil leak fixed.

Article Details

Wed, 03/01/2017 (All day)

Richard McCuistian

<p>One serious problem cloaks another one to the point that the first fix isn&rsquo;t the final one &mdash; and some customers are more understanding than others.</p>

<p>Titan, Altima, thermistor</p>

Whenever we get a vehicle in for one simple service and find a lot of other stuff that needs attention, any well-trained, reliable technician will make a list of the needed repairs for the customer, putting the safety-related ones at the top — loose front end parts, failing brakes, expired or worn out or expired tires, and so on.  The caveat is that if a customer is shocked by a large estimate of needed repairs they didn’t expect, they’ll tell all their friends your shop tried to sell them the moon. And today, it doesn’t take many needed repairs to produce an estimate that climbs off the chart above what some customers can afford to have done. Even if they can afford the repairs, some savvy customers will opt to get a second opinion, so honesty is always key when making a list like that.

Show and tell is the best way to handle those situations. And your communication skills must peak in situations like this. Someone has quoted Einstein as having said, “If you can't explain it to a six-year-old, you don't understand it yourself.” And we all know some customers are sharper than others when it comes to absorbing what you’re telling them.

This canteen green Pathfinder hadn’t darkened our door before, but we had done numerous jobs for these folks on their other vehicles.

The other way the laundry list estimate goes is when they bring one with them when they come, and in my department, we get that regularly. These folks are typically the busy drivers who have been putting off first one repair and then another one for quite a few thousands of miles and then they’ll decide they want all those problems handled all at once. And some of their repairs aren’t quick and easy, either.

One of the recent ones we got was a 2005 F-150 with an inoperative moon roof that was stuck in the open position, no taillights, inoperative outside rearview mirrors and an erratic gas gauge. That same day we got a 2009 Chevy C2500 with a “fix whatever you find wrong” order, and there was quite a lot we had to do to that one. Then there was the 2005 Nissan Pathfinder with a laundry list that was a knuckle-busting adventure from beginning to end.

Happy customers

This family loves the work we do, and they tend to bring us most of it, but this was the first time we had ever seen the Pathfinder, which had 185,654 miles on the odometer. On the phone, the owner told me the instrument cluster was acting crazy, and I figured that’s all she wanted done initially, but then by the time her husband got there with it, she also wanted the heater core replaced – what an afterthought that was! It had long ago been bypassed.

As for the instrument cluster, it was doing wacky things. The temp gauge, the tach and the speedometer would come and go, and the brake, ABS and VDC warning lights would flash on and off just as randomly. The scan revealed a network code or two, but not much else. One thing we did notice is that the cluster couldn’t communicate during the dead-needle times. Filing that away mentally, I had Thomas launch into the heater core job.

In the meantime, the two other laundry-list vehicles rolled in. That 2009 2500 series Silverado mentioned earlier had been neglected for many a mile and year, with StabiliTrak and Tire Pressure Monitor messages, a gaggle of inoperative and busted lights and inoperative door locks. The 2005 F-150 was one a police officer brought in with an inoperative moon roof, tail lamps that didn’t work and a squirrely gas gauge.

The Silverado wasn’t all that interesting, except for the StabiliTrak message displayed on the cluster. The DTC and the troubleshooting led to the replacement of the steering angle sensor, which was fairly involved because of the rusty, dusty fasteners. Robert jerked the steering column out, put it in a vise, and did the surgery – that took care of the StabiliTrak. The rest of the repairs were fairly straightforward, but we did need to mount a couple of universal tag lights in the rear bumper – you can get a traffic ticket in these parts if your tag lights are out. We also replaced the busted CHMSL/Cargo lamp assembly. We replaced the driver-side power door lock switch for corrosion, but then found two of the four door-lock actuators were dead, along with two of the tire pressure monitor sensors.

The 2005 F-150’s moon roof was open and wouldn’t close (not good on rainy days), and so when we ran through the process of checking switches and wires we found a bad moon roof motor. We left the permanent magnet casing off the motor, remounted it and turned the armature with fingers to close the moon roof, because he didn’t want to spend the $300 on a motor. The issue with the gas gauge and the taillights had its roots in an oddly melted connector shell just outside the frame rail on the left side. The wires leading into the front side of that connector looked like a flame had been held under them — the tape and insulation was melted, and that side of the connector was, too. We could twist and wiggle the connector and get taillight and gas gauge normalization, and so we opted to clip that connector out and bypass every wire with solder and heat shrink. It was a good repair, because even if we were to find new replacement connector shells for this, they’d be too expensive.

On the 2005 F-150, this oddball melting almost looked like somebody had built a fire under it at some point – when we wiggled it, the tail lights and the gas gauge would go nuts, so we removed the connector and made the harnesses one at that point.

A patch job and a no-fueler

One of our directors owns a fairly decent little 2001 Tacoma he uses for deer hunting, and he came to me one day because he was having to add a gallon of water a week to keep the cooling system filled. It turned out that the coolant was making its way into one of the cylinders and out the tailpipe — one of the spark plugs was ultra-rusted. He made it plain that he didn’t want to start with a head job on that deer hunting truck, and so he asked if I had any other ideas. For his purposes, we decided to run some head gasket sealer through it, carefully following the instructions on the bottle for time, then we refilled it with coolant mix. About a month later he came by and told me that he hadn’t had to add any more water. Take that for what it’s worth.  When somebody’s in a bind, we do what they ask if it’s not dangerous.

This was the rusty plug from the Toyota Tacoma that fingered the cylinder head gasket as the cause of coolant loss. The liquid head gasket sealer paid off on this one. We’ll see how long it lasts.

About that time a 1999 Lexus rolled in that wouldn’t take gas at the pump, which can be one of the most frustrating issues known to man, and we found a plugged vent hose. Some insect lost his homestead and that customer was a lot less frustrated the next time he pulled up to the pump.

Even in the south, we get seized parts, and they’re always fun to deal with. One thing we do get a lot of down here are dirt-dabber nests in annoying places – the Lexus wouldn’t take gas with this clog.

Back to the Pathfinder

With the heater core in place on the Pathfinder, Thomas came to inform me that the brittle heater pipe manifold under the hood had broken when he was reattaching the hoses to the heater core, and this wasn’t something we could fix, so we ordered the $220+ manifold with its built-in plastic water pump and did that job up right. Filling the cooling system was challenging, but with the front jacked up, we managed to make it happen.

Before we re-attacked the cluster issue, we figured we’d do the alignment, and Thomas started out with the rear wheels because we always align those first if there are adjustments. The problem was that the adjustment bolts were rusted to the bushing sleeves on one side and the first bolt he fought with popped off right below the nut, which had become an irremovable part of the bolt. This was becoming difficult and irritating beyond words.

The rear control arm adventure was quite the knucklebuster. We attempted to drill this (didn’t have a Rescue Bit® on hand), but it was pointless. We opted to engage the high speed cutter, get some replacement cam bolts, and put a new control arm on it.

I called the owner to enlighten her, and she told me the Pathfinder had found most of its early paths at the beach, because that’s where it lived for the first five years of its life. Yeah, I know you Northern wrench guys see this every day, but we aren’t used to it down here in the south, although we do see some rides from up your way now and then. We ordered replacement cam bolts from Nissan and a lower control arm from the parts store, but to get the old control arm out of there we had to use the high-speed cutter’s 4-inch wheel to clip the adjustment bolts just inside the flanges.

Got that part of the job done, finished the alignment, and then we went after the cluster. Checking the network with the Pico, we found a pattern that was somewhat noisy, but after eliminating first one module and the other to no avail, we decided the cluster itself must be at fault because sometimes it’d talk and sometimes it wouldn’t.

The Pico pattern always looked pretty much the same, so after disconnecting every module on the network (one at a time, we decided to replace the cluster and that’s all it needed to normalize the needles.

This cluster is a plug-and-play unit, and when we told the customer what we had decided, the owner found a used one for $75, and when we popped it in there everything was peachy keen.

The 2009 F-150 transmission problem

In and among all these jobs, we had a 2009 F-150 with intermittent 6R80 transmission problems. The symptom was that the truck would have spells where it wouldn’t back up and during those times it would also stick in third gear until you cleared the codes. We were told that a transmission shop had pulled the pan and found good fluid and no debris, and they were kind of stymied as to what needed to be done next, so they sewed it up and the owner brought the truck to us.

We got a Transmission Range sensor code, but that was pretty much it. In the years that I’ve done this, it’s a pretty good bet that the transmission control module (or PCM) is suspect if the transmission starts acting strange and wiping the codes clears it up for a while. This is obviously not always the case — sometimes the transmission controller will go into limp-in mode for other reasons. With zero experience on this 6R80 gearbox, I called one of my guys who does them all the time — only he’s accustomed to the newer ones. He told me we’d need the “leadframe,” because he has to change them regularly for this kind of problem. That device looks like a big hard-wire harness with the speed sensors built in, but it’s actually the Transmission Control Module. Why they call it the “leadframe” is beyond me.

This is the “leadframe” as Ford calls it that actually turns out to be the TCM.  We wound up having to replace the whole valve body on this 2009 F150 – when we first removed the valve body we found this broken adapter and replaced it. And every time, we were careful to use a torque wrench when reinstalling the valve body.

My guy decided to help out and called the parts department to ask if they had one, and then I called, gave them a purchase order, and they billed it out at $125. The way this went down was a perfect-storm situation, because the year model was lost somewhere in the process of passing information from pillar to post, and it cost us some work.

When we pulled the valve body to replace the leadframe, we saw that the plastic-and-rubber adapter between the valve body and the pump was cracked, and so I got another one of those from my guy at the Ford place. The only problem was that when we put everything back together put the fluid in, we found that the transmission wouldn’t engage at all and the TCM (leadframe) wouldn’t talk to the IDS either. But we could plug the old leadframe into the wires and let it swing and it’d talk to the tool just fine.  What was going on here?

This was strange to me — for years Ford told us that electronics couldn’t cause a no-engagement issue, but here it was. Things have obviously changed. With the absence of electronics, this one dumps the pressure instead of raising it.

It was then we discovered you can’t buy a leadframe for a 2009 model — you have to buy the whole valve body, leadframe and all ($1,000). And even though the later leadframes look identical and are replaceable separately, they won’t talk to the IDS and they won’t function on a 2009 model. So we got a whole valve body, installed and torqued it, did the fluid fill, and fixed the truck. It was messy but fun pumping transmission oil into that one through the hole where the dipstick tube used to go and checking it with that tiny plastic dipstick right next to the catalyst with the engine running and hot. That was a knuckle-BURNER. One way or another, we won that fight and all the rest of them on this round, with busted and burned knuckles galore. Who knows what we’ll see next week?

Article Details

Fri, 06/02/2017 (All day)

Richard McCuistian

<p>Whenever we get a vehicle in for one simple service and find a lot of other stuff that needs attention, any well-trained, reliable technician will make a list of the needed repairs for the customer, putting the safety-related ones at the top.</p>

<p>F-150, customers, estimate</p>

Those of us who have been in this industry a long time can remember when a vehicle was pretty much used up at the 100k mark. Odometers “rolled over” after 99,999. I read somewhere that in the 1930s, most engines needed rebuilding every 10-20K miles. Technology has certainly improved, and there are more than a few brands out there that can rack up some stratospheric odometer numbers with very few debilitating problems along the way.

When I worked at the dealer, we saw more than a few Ford pickups and Jeep Cherokees with 300-400K miles. The folks with Jeep Cherokees would keep the one they had driven hundreds of thousands of miles and buy another one. A few years back, my department was given a 1997 Pontiac Grand Prix with 250k on the clock and it still runs like a new car, even though the interior trim has aged to the point of coming apart in places.

This is one of those stealth problems — one of my guys had replaced the radiator in this high mileage Ranger, and since the lower radiator hose clamp had seemed okay, he re-used it. What he couldn’t see was that this clamp wasn’t quite long enough — the screw was only holding a couple of slots, and they gave way one day about six weeks after the radiator was replaced and dumped the coolant.

Some of the customers’ vehicles we work on in my department are low-mileage cars only a couple of years old, but we spend a fair amount of time on older ones. This time around there are several jobs to discuss; the most recent one we did yesterday. It was a high-mileage 2010 Ford Edge that had developed a serious transmission cooler leak after hitting a dog, and she had driven it until it was six quarts low on fluid before realizing that there was some serious dripping going on. As a side note, while it was on the lift, the lift itself breached a hydraulic hose and started leaking, and we had to fix that too – my contention is that that the transmission leak on the Edge was contagious. That one got a transmission cooler and the six quarts of replacement juice and the lift got $200 worth of new hydraulic hoses. Two crises dealt with in tandem.

Another recent one was a 2004 Trailblazer that rolled in with really high miles, an engine skip and a $450 estimate another shop had given her to fix that skip. They had proposed those $13 apiece Iridium spark plugs and a whole set of new coils. Well, this gal is a single mother and rejected that estimate out of hand. We pulled the codes, found a misfire on the No. 1 hole, did a compression test for good measure, then put a set of platinum plugs in there and a single coil.  For grins, we also polished the headlights, which had taken on the color and cloudy opacity that might be compared to dirty lemon juice. And yeah, we don’t charge labor, but why does a vehicle that old need the most expensive plugs and a whole set of coils? There is such a thing as pricing yourself out of a repair.

The Avalanche

The Avalanche

A lady called me one week while I was off during a break and asked if I’d have a look at a 2003 Mazda B3000 she had sitting on the curb in front of her house. The story on that one was that it was her son’s truck and that it had failed to start one night in a parking lot and they had tried to jump it off with no results. Figuring it was a bad starter, they simply parked it (strange, I know, but that’s what happened). It had been sitting there for three months when I opened the hood, noticed that the battery had been removed, connected my 30-lb. jumper cables, and fired it up. Faux jumper cable connections on crummy battery cables can de-rail a DIY diagnosis of a no-crank in short order. The B3000 ran like brand new and even had cold air, so she washed it and got it ready for a quick sale. A couple of weeks later it failed to start at the car wash, but that turned out to be a tripped inertia switch – somebody must have slammed the door or kicked it or something. But during the three months the Mazda was down, she had sold the boy her 2004 Chevy Avalanche and had bought herself a newer truck.

Now her son reported that the Avalanche, which boasted 268,587 miles, was leaking power steering fluid, and she wanted to know if we could check that out. I agreed, and when the truck arrived, we discovered that it had a dreadful engine oil leak that made the power steering leak look like a minor drip. It was odd that he was more concerned with having to add a half a pint of power steering fluid once a week than he was that the engine was bleeding oil to the point of what could be an early death. When I asked him how much engine oil he was having to add, it turned out to be a quart every two or three days. Yet the first thing on his mind was the power steering leak, probably because it’d whine and get his attention and he was tired of that. Squeaky wheel gets the grease, I suppose.

Well, we went after the oil leak first – it was dripping off the bell housing, but since that’s the lowest place, the leak might be coming from the pan gasket, the oil filter adapter or the intake. The bell housing was dry on the outside leading up to the intake, and it didn’t look like the oil pan was leaking (which these love to do). We looked closely at the oil filter housing before popping the small round cover off the underside of the bell housing, and through that hole, we found engine oil puddled in there, pointing to a rear main seal. We would attack that first, proposing the rear main, a torque converter seal and an oil pan gasket just for grins, since GM was kind enough to put a crossmember under the oil pan and make that part of it an easy fix.

My guys plowed into that one, and we were extremely happy it wasn’t one of those later model GM platforms with the stainless steel exhaust fasteners. Whoever came up with that idea should be chastised harshly. You can’t cut those stainless nuts with a torch and heating them doesn’t help either. But I digress.

The Explorer

This 2008 Explorer had been in who knows how many times for oil changes. The instructor who drives it makes a 120-mile round trip to work and back, and once a couple of years ago she came in with a bad engine vibration due to a busted cooling fan and two full-grown dead cats lying in the bottom of the fan shroud.  On another trip, the pulley ring of her harmonic balancer had slipped back toward the engine so that the belt was riding on the naked rubber part of the balancer, and the crank sensor was being machined away by the misplaced pulley. We saw two of those slipped 4.0L balancer failures that same week and haven’t seen another one since.

	This 2008 Explorer had been the equivalent of 10 trips around the world before the spark plugs were finally replaced, but it still ran like a champ.

On a humorous note, we decided on one trip to check the fuel filter on the Explorer, which was almost completely blocked. I used that for an object lesson as to why it’s always a good idea to check the fuel filter on a high-mileage vehicle. There was a time when Ford required the filter replaced every 15K on trucks. Later when I was changing the oil on my 2007 Taurus I decided to check the fuel filter and it was just as bad as hers was.

On the last oil change, I suggested we have a look at her spark plugs and it turned out that they were the originals – with 238,000 accumulated miles, and this one was still running great with not so much as a flicker from the MIL. The plugs had the paint spot on the tip and on the way out they did that heavy-duty squeaking ancient spark plugs do when they’ve been in there forever. Furthermore, the business end of those plugs was textbook worthy.

The Suburban

About the time we got the transmission out of the Avalanche, a high-mileage 2004 Chevy Suburban came rolling in with an engine skip that turned out to be on cylinder 4. This one was blessed with the trusty old 5.3L, which I like because of the camshaft-in-the block, but even without the overhead cams and all those nylon sliders and tensioners, this engine isn’t without its problems. Camshaft lobes wear down and head gaskets blow. When we pulled the plug out of the misfiring cylinder, there was a piece of ceramic that had been cracked and shucked off the center electrode sheath by some catastrophic mechanical event (that according to the Denso chart anyway), and that cylinder had no compression. A cylinder leakage test fingered the exhaust valve, and I wondered if that chipped-off piece of ceramic might be stuck in some valve carbon holding the valve open, but it would seem to have been hammered to bits and spit out the back, because that’s what usually happens.

We won’t know until later this summer what happened on the 2004 Suburban to cause this, but the cylinder it came from has almost no compression at all, and since the mileage is so high we’ll probably stuff an engine in it.

The prevailing question I had was what had caused the spark plug’s ceramic to fail in the first place. Were there detonation or preignition events that cracked and damaged it or what? They had to go on a trip and opted to drive it that way, but in the coming month we’ll stuff an engine in that one – the cool thing is that we can upgrade to a 6.0L if we want to because the 4.8L, 5.3L, and 6.0L are plug-and-play engines.

The ’98 F-150

One of my colleagues owns an F-150 he inherited from a relative, and we got one of those laundry list requests – the fuel economy had dropped off, the passenger side power window wouldn’t work, the transmission needed servicing, the intermittent wipers were intermittent, and, of all things, the Check Engine light didn’t work – and he wanted all of it fixed. A lot of people “fix” the MIL by covering it with a picture of somebody or by installing a piece of tape blocking the view of it, but this one had a breach in the wire between pin 2 on the PCM and pin 13 on the bulkhead connector, so we did an overlay on that one and brought the MIL back to life. Several of my people worked on that problem because it was a great troubleshooting and repair exercise in electrical systems, and it was a bug I didn’t plant.

This ’98 F150 had a laundry list of issues, the least likely of which was the inoperative check engine light.  We ran an overlay between the PCM connector and this bulkhead connector and got the light back online.

For a truck this old, that re-operational MIL might be problematic, because now, if the truck had issues of which he had previously been oblivious, he’d be swinging by regularly to have those issues handled. After we replaced the spark plugs, the passenger-side window regulator, the PRNDL indicator and the Combination Switch, the truck had no starter operation, and we tracked that to the big C172 connector near the battery – one of the students had begun disconnecting that connector, gotten side tracked, and left it that way. In the end, that F-150 rolled out with no codes and no illuminated MIL, which was something of a surprise on such a high miler.

The hunting truck and a Nissan

The Toyota pickup on which we had used head gasket sealer came back in for a timing belt and a water pump – it still wasn’t leaking coolant any more, not even from the water pump, but the bearings in the pump were rattling, and so we stripped it down and did the kit thing – belt, idler, tensioner, water pump, etc. After we filled it with coolant and fired it up to do the final burp-out, I saw coolant leaking from the rear of the engine and discovered a head gasket breach that was trickling coolant down the bell housing. Whether he’ll want to redo the head gasket sealer or replace the head gasket remains out with the jury, but he opted to take the truck and use it for a while, keeping a check on the coolant level. His prerogative, I suppose.

The Toyota hunting truck revealed this leak after we did a water pump and a timing belt.  It was a tough shot to get, but in the real world you can see coolant trickling from under the right cylinder head. This stain told the tale.

Then there was the 2000 Nissan Frontier with an A/C belt squeak after a few minutes of at-idle A/C operation. This was condenser airflow-related because the head pressure started out normal and slowly climbed until the compressor had to struggle. Checking for radiator and condenser fin blockage, we rinsed them out with soap for good measure but to no avail. When we put a fan in front of the condenser blowing through it, the pressures normalized, and when we tested the fan clutch by heating the bimetal spring, it never got any stiffer, so we fixed that one with a fan clutch.

Finishing up the Avalanche

The power steering leak on the Avalanche was the last thing we tackled on that one. It wasn’t leaking from the pressure hose as we had figured. It was dripping fluid from the hydroboost unit, and so it’d need one of those babies to close out that job. We got one from the parts store, swapped it out, refilled everything, used the vacuum bleed cap I built to purge the air, I charged out the parts, and we put that one on the yard. Oh, yeah, we polished the headlights on that one too, and the whole truck looked better. “It’s the little things,” as one customer told us. We do what we can to breathe new life into those high milers, and it felt good to be done with another one.

Article Details

Tue, 08/01/2017 (All day)

Richard McCuistian

<p>The ones that just keep on givin&rsquo; sometimes need help.</p>

<p>high-mileage, vehicles, leaks</p>

The catalytic converter was introduced nearly 50 years ago because of EPA-ordered cuts in emissions, and in response to those orders, auto industry execs said the EPA’s targets could never be met. But thanks to old-fashioned American ingenuity, they were. What the EPA conceives, our engineers always achieve. Fuel-cell engineer Jonathan Frost once said: "When the U.S. introduced clean air legislation in the 1970s, many engineers said that cleaning up emissions from cars was impossible, but the legislation was passed anyway and new technology was invented in the form of the catalytic converter."

In 1972, Ford President Lee Iacocca said that “if the EPA does not suspend the catalytic converter rule, it will cause Ford to shut down.” He was obviously wrong, but at the time, the prevailing wisdom was that the catalytic converter was a near-impossible concept, overly expensive and inefficient, pegged as an idea that would never, ever work.

These honeycombs are tough enough to do the very precise job required of them, but fragile enough to be rendered ineffective if things go wrong and stay wrong for a while.

The 1970 mandate that auto manufacturers would be required to reduce harmful emissions by 90 percent by the 1975 model year drove Engelhard Industries and Corning Glass to propose the device that would later become the catalytic converter. A “catalyst” foists chemical changes on other elements while resisting any change in itself. The catalytic converter adds the necessary oxygen molecules to CO and HC (the exhaust from rich mixtures), to change those harmful elements into CO₂, which is the same thing we breathe out. The exhaust gases flow from the combustion chambers through the catalytic converter’s core, which is a block of ceramic material honeycombed with tiny lengthwise channels, designed to force every cubic millimeter of the gasses into contact with the catalyst material, and that’s where the necessary changes take place.

Lab work finally proved that a catalytic converter would work, but mass-producing them became a new and even more difficult hurdle. Engineers would have to take an abrasive clay mixture and force it through a shaped die at high speed to create the complexities of structure we see in cat-cons today. This process is called “extrusion” and at the time it was very commonly used for creating things like metal pipes and hollow noodles, but nothing anywhere near this complex had ever been attempted. It was a daunting task.

But that wasn’t all. Once that soft block of honeycombed clay emerged from the die, it first had to be cut to the proper length and then heated simultaneously inside and out until it was totally firm. And all this had to be done without distorting those tiny channels or causing the clay to crack, and then they had to find a way to coat all the channels with a layer of very fine platinum particles so that the platinum wouldn’t simply fall off after repeated (and vast) temperature swings. Under normal conditions, a catalytic converter races from ambient temperature to 800° F in 30 seconds, and the temperature of the gases can climb as high as 2,000 degrees. The catalysts on the vehicles I’ve datastreamed lately will normally float between 1000 and 1700°F while driving. In early development, on nearly every prototype, thermal expansion ruined the guts of the converter after just a few drive cycles.

The contrast between a pair of good catalysts (top) and a bad one is easy to spot using the PIDs.  If the rear O2s mirror the front ones this completely (bottom) the cats are no longer cats.

But then it was discovered that samples of clay from one mine in Georgia showed much better heat resistance. This clay turned out to consist of microscopic needle-like units aligned in such a way as to withstand the thermal expansion, and that was the key to making a cat that would last. The cats were off and running, and it has since become our job as technicians to herd them.

Front and rear

Nowadays we’re accustomed to seeing the “light off” cat(s) mounted very near the exhaust manifold(s) to take advantage of the natural heat still present as the exhaust has just made its exit from the combustion event – this front cat is the one sandwiched between the front and rear O₂ sensors, and the oxygen that is stored in this converter is extracted from the NO_X that is created during the combustion process, leaving N₂, which, to quote Bernie Thompson, is the cylinder’s “working fluid” — combustion heats the nitrogen so that it expands against the head of the piston, pushing it down and spinning the crank around. The oxygen extracted from NO_X in the front cat is used in the rear cat to handle CO and HC, converting them to harmless CO₂, oxygen, and water vapor, which is also created during combustion.

The aft-cat O₂ sensor monitors oxygen storage and that sensor’s signal should switch much more sluggishly than the front O₂, but if the rear O₂ begins to register a problem, the PCM will do what it must with the fuel trim to keep the rear O₂ (and the cat) happy, so be ready for that in case you ever see it happening.

This display shows healthy cat activity, but also healthy cat temperatures (Celsius). I have set the Android radio I have in my 2006 Explorer to display these parameters during normal driving. The diagram shows which gasses are handled by the converters. The front one is the “light off” cat.

So, what damages the cat? Well, engine misfires (caused by no spark or low compression) can lead to overheating and potential meltdown of the substrate. It can be contaminated by silicone sealants (or liquid spray), coolant leaks into the combustion chamber that coat the strata, excessive oil steam blow by that is picked up and processed by the PCV system and sent out the exhaust, high sulfur fuel, and rich fuel mixtures forming carbon deposits. Any of these elements (and some others, like leaded fuel) can quickly coat the catalytic substrate, effectively preventing it from working effectively. Catalysts sometimes just wear out. The brick may break loose inside the shell and dance around in there or chunks may break off the engine side of the cat and rattle around, preventing good exhaust flow. Overheating can also cause cats to break up into dusty, abrasive particles that find their way through the EGR system and into the combustion chamber, a scenario that is an engine killer of the first magnitude. And there are times I’ve seen the vermiculite blanket around the outside of the brick shed material that will clog enough of the passages that exhaust backpressure rises and the engine begins to lose power because it can’t breathe.

The codes and the protective PCM

Just about everybody has seen the P0420 and 430 codes flagged because the rear O₂ is reflecting poor oxygen storage, but that doesn’t always mean the cat is bad. The honeycomb will sometimes be coated with one element or another that might well be burned off when the rest of the system is repaired to work right. With that in mind, other DTCs should be carefully considered before condemnation of the cat. Hydrocarbon soot initially cools the cat and makes the O₂ sensors sluggish, (skewing the mixture even more) and the soot coating prevents the precious metal substrate from doing its job.

Problems maintaining fuel control can prevent a catalytic converter from working at all. The cat needs a very precise mix of feed gasses to “light off,” and the range expressed in Lambda is very narrow indeed — 1.005-0.995.

Whenever you see other codes displayed that can have an effect on the efficiency of the cat(s), go after those codes first, then complete a couple of drive cycles to see if the cats will clean up their act and start working right.

One of the first times I encountered PCM cat protection was in the late ’90s when I was working on a Windstar that had all the EGR ports clogged except number four. When EGR was flowing, that one cylinder was getting it all, which created a somewhat mysterious misfire in warm off-idle mode. When I started working on that one, I noticed that when I cracked the throttle, it would begin a very steady misfire on four, and as I was doing my troubleshooting, I noticed that when the misfire was under way, the number four injector would stop clicking, which led me to believe there was a problem in that area. Not knowing that the PCM strategy was shutting the injector down to protect the cat, I did some circuit tracing before I realized that disabling the EGR did away with the skipping, and that’s when I found the reason for the misfire. Ford’s instructors had, at that point, never told me about that strategy in training, but maybe I missed it while I was grabbing a cup of coffee.

If the rear sensor picks up on a consistently dreadful imbalance at the cat’s exit stream and reports it to the PCM, the box might realize that the front O₂ is unreliable and fuel trim strategy might be modified based on the rear O₂ feedback to protect the cat. This will vary from platform to platform, but the PCM’s concern about the cat’s health is very real.

Once again, all other codes related to air/fuel should be addressed first. MAF, IAT, ECT, rich/lean codes and fuel trim issues would be the focus, along with a careful consideration of the EVAP system and even the condition of the engine oil, both of which can be the source of excessive HC.

After dealing with the other pertinent codes, make sure you’ve recorded them, erase them, and then start the engine. Hold it at about 2500 to light off the cat, all the while watching front and rear O₂ sensors. With a front O₂ switching rapidly and a rear O₂ trace a lot less active, the converter should be OK. But if the rear O₂ sensor is mimicking the front one on a system that is otherwise healthy, the converter is probably ready for the scrap pile, but it’d be wise to dump the codes and complete a drive cycle to see if the converter monitor will flag a problem with the cat before you make your final decision. And there are other considerations.

If the only code is a cat efficiency code, check out the freeze-frame data. If the fuel trim was high when the code was set, it might indicate unmetered air, unreliable MAF readings, or a skewed BARO reading from a speed-density MAP sensor; the fuel pulse will be wrong, and that’ll create a genuine lean condition. The PCM will respond to the O₂ sensor(s) lean reporting by dumping extra fuel into the intake to bring things back into balance. If this is happening on just one bank, it’s not likely to be MAF or MAP related and more likely to be something only affecting that bank.

Whenever these shenanigans have taken place (for whatever reason), there’ll be MIL lights and contraband, poisonous gasses galore.  The 2003 Wrangler got a $400 bolt on replacement set.  It had been purchased used by a doctor who wanted this “mod” reversed.

If the fuel trim is double-digit negative, it typically indicates extra unmetered fuel is finding its way into the chambers and the ECM is compensating by subtracting pulse time. This can be fuel injector pressure regulator related, either because the regulator diaphragm is leaking or because it isn’t regulating the pressure at all – shoving 100+ psi of fuel through the nozzles. I’ve seen that more than a few times. And cam timing errors can cause fuel trim anomalies too, so watch out for that.

Visuals and audibles

A cat that is dented or rattling is obviously in need of replacement, because the brick usually can’t take that kind of thing without suffering damage. A discolored converter (“blued and hued,” like some gun parts) is also suspect, because it must get blistering hot to change color that way. It’s also a good idea to get eyes on the front of the brick with a borescope or whatever method you can – if it has clogged combs, is breaking up, or is obviously contaminated, it’ll need replacing, but first you need to find the source of any contamination. You need to find the cause before you attack the effect. Temperature and backpressure tests are a good idea too – it should be hotter at the outlet than at the inlet, and you shouldn’t have more than about a pound of pressure in front of the cat – a good one won’t even have that much. Keep in mind that the temperature test only tells you whether or not the conditions are right for the cat to light. It, alone, does not mean the cat is no good.

Another common cause of P0420/0430 DTCs are leaky exhaust systems. Even pinhole leaks can suck enough oxygen in to cause a problem. Use your smoke machine to locate the presence of leaks, especially any upstream from the cat and within a foot or two of the backside of the cat.

Then there are those converters that look just fine on the outside but have been gutted by somebody for one reason or another. Back in the 1980s when I was working at a large Ford dealer, some of the mechanics would buy a brand-new truck and immediately have the exhaust system totally re-done – doing away with the cats in the process. For the life of me I’ve never been able to understand why somebody would do that to a new vehicle.

Finally, the only really reliable test to find a partially clogged cat (my opinion) is the backpressure test taken at the O2 sensor port.  The cat pictured here had only 5 psi of backpressure and the customer’s complaint was low power, harsh transmission shifts, and poor fuel economy. Less than 2 psi backpressure is optimum.

The overarching point is that not every catalyst efficiency code necessarily condemns the cat, although there are many times when that is the case, particularly if everything else is as it should be.

If you’re replacing the cat with anything other than an OEM, make sure you get one that meets the application, and not a “universal” – not all cats are created equal. Back in the 1990s we diagnosed a dead one at the dealer and let the customer talk us into having a replacement put on at a local muffler shop. The replacement converter threw efficiency codes on the first drive cycle. Today, even using one that “looks” right may lead to repeat codes.

Article Details

Thu, 09/28/2017 (All day)

Richard McCuistian

<p>So, what damages the cat? Well, engine misfires can lead to overheating and potential meltdown of the substrate. It can be contaminated by silicone sealants (or liquid spray), coolant leaks into the combustion chamber that coat the strata, excessive oil steam blow, and more</p>

<p>catalytic converter, PCM, auto repair</p>

One day I got a very terse call from the vice president of the company where I was responsible for fleet maintenance back in the late ‘70s. It seemed that an almost new (1978) Dodge one-ton we had was pointed at the gate with a gooseneck trailer behind it and that truck and trailer needed to arrive at our offshore diving and salvaging dock within the next 30 minutes – 25 miles away. I had no idea why that trip to that dock was so urgent, but someone had misplaced the key to the Dodge.

“Get that truck started and on the road within the next 10 minutes,” he told me with his gravelly voice, “and I don’t care what it takes. Just make it happen.” 

I must admit that I was in my element under pressure in those days, so I hung up the phone and grabbed a jumper wire with a couple of ‘gator clips on each end out of my toolbox. I opened the hood on the Dodge and made a connection from the positive battery terminal to the ballast resistor to feed current to the ignition coil. Making sure the tranny was in neutral, I “pocket screwdrivered” the starter to fire the engine up. Ninety seconds had expired and the steering wheel was still locked, but I knew I could defeat the pewter collar around that silly spring-loaded steering wheel lock peg, and I slid into the seat and muscled the wheel hard to the right, and broke the lock. Mission accomplished in less than three minutes and the truck was headed out the gate.

Then there was the time at that same job where I had to drive down Highway 87 toward Galveston and take a steamy ride on one marsh buggy through a swarm of mosquitoes and dragonflies to another marsh buggy that had jumped time, stranding a different vice president and his passengers a couple of miles off the road. Putting a timing belt on while standing in snake and alligator-infested water and swatting away mosquitoes wasn’t my idea of a good time, but I was motivated enough that I got that job done in record time, too.

This is my 2007 F150 that was victim of a surgical strike by some toothy critter that was copper-hungry

The point is that every job isn’t interesting, but in our line of work, challenges are the spice of life, and it feels good to be a problem-solver. It feels even better to be appreciated, and usually we are, but that isn’t always the case.

Critters

Dogs and squirrels chew wires, as do rats. Rats and squirrels build nests in engine compartments, and cats looking for a warm place to sleep can die under the hood and under the car in very gruesome ways sometimes. I’ve had to kill spiders and roaches, wasps, dirt daubers and all manner of other wildlife in my under-the-hood and under-the-vehicle odysseys. One morning I did a classroom presentation on critter damage, and a day or so later I walked out to where I park my own F-150, slid in behind the wheel, and thought I was going somewhere in my truck, but it wasn’t to be. The battery was good and hot, but I had no starter operation and no scan tool communication. The red theft light was blinking, which can point to a few different problems, but it usually means a module (usually the PCM) isn’t talking. With the key on, I checked for voltage at the EGR assembly and found 9 volts on the gray-red signal return wire – which should have been grounded through the PCM. What that meant to me was that the PCM had lost its own ground reference somehow.

Having Alldata available on the smartphone is pretty handy when you’re under the gun to find out what’s wrong and you’re somewhere else besides the shop

Next it was time to bust out my smart phone and dig into ALLDATA, where I found that PCM G103 is located behind the battery on the bulkhead. With my flashlight, I peered down there and saw that about eight inches of that wire had been removed by some sharp little teeth and my much larger main power feed cable to the inside fuse panel had been just as viciously attacked, but it had survived without being severed. Some chew-happy squirrel must have a nice piece of wire lining its nest and a belly full of copper as I type these words.

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There was another ground wire in that same area that was compromised as well. While removing the battery and doing some solder and heat shrink work was almost enjoyable that Saturday morning, I found myself wondering if I was going to have this problem again. No other wires under the hood had been attacked.  It was almost like the critter had pulled up a wiring schematic and did a surgical strike to prevent my truck from going anywhere. And it worked.

I suppose I should have been thankful that these wires were the only ones the critter chewed – he could have done a lot more damage than he did – fixing this took about thirty minutes.

I prevailed in that fix and placed some rat poison in the general area. We’ll see how that works out.

The 2004 Suburban

In a previous article, I mentioned a 2004 Suburban with a 5.3L that was misfiring on cylinder 4 with low compression and, during the cylinder leakage test air was escaping into the exhaust, but the owner chose to drive it skipping for a while before having it fixed. Finally, the Suburban returned and we hashed out what needed doing.

This was one of those high-milers, and so I talked them into a reman engine because of the better warranty, which we managed to stuff in there in pretty good time. 

We were going back into the Suburban with the reman engine and had just put it in place when this photo was taken. You can see the burned valve in this photo of the old engine’s head if you know what to look for.

After the swap, I had Robbie jerk the head off so we could inspect the valves and the head of the piston on the offending cylinder and we found a valve that had become mis-matched with its seat and was leaking compression. With the new engine in place, the MIL was off, the monitors all cleared, O2 sensors were switching handily, and fuel trims were bouncing around the zero line, so we put that one back on the road. There was a strange caveat though. For some reason, the transmission wouldn’t go into park well enough to not roll away on a slope.

This was a deal-breaker, to be sure. The shift cable was adjusted as far as it could go. I could disconnect the cable and put the transmission fully in park, so there was nothing wrong inside the case. Eventually I decided to try the shift lever off another transmission I had on the shelf and with that lever installed, it would go completely into park just fine even though it looked the same. I have yet to figure that one out, but it was safe when it left.

The Silverado, the Fusion, and the MKZ

While all this was going on, another instructor who drives a 2003 Silverado 2500 Duramax asked if we could replace his master cylinder. He’s ordinarily pretty savvy, and since he brought us the master cylinder I had a guy pop it on there and begin the bleeding process. Well, the pedal felt like you were stepping on a plum, and there was fluid dripping from underneath the truck and we found that classic rusty brake line situation a lot of you guys have to fix every day. He didn’t look under the truck, I don’t guess. A careful exam of the whole system revealed that this line was a lot worse than any of the other lines, all of which looked pretty good, and so we got a roll of that dandy nickel-alloy rust-free stuff and built a replacement line from stem to stern (complete with new double flare fittings), and after the bleeding procedure, we got that one rolling again with a good firm pedal and a master cylinder he didn’t need. I gave him the rest of that $60 roll of brake line just in case something else would be needed later.

This rusty brake line syndrome is fairly common everywhere on trucks of all kinds, especially on trucks that do a lot of mudding, but salt did this one in. This Silverado had spent its early life in Panama City Florida, where the salt air took its toll.

The 2010 Fusion that came in around this time was making a bump noise underneath on the left side during parking lot maneuvers, and it was one of those cranky situations where you can’t see anything but you know something is wrong. And every bolt was tightened to no avail. This one has that odd double-ball joint design with two lower control arms, and when we applied the Chassis Ear^® we found that one of the control arms was the source of the bump, and when we got it out of there you could see the problem. The hidden rubber that is couched in the frame area had died, and that was allowing the sudden pressure of certain braking and steering maneuvers to give a metal-to-metal contact sound. The fix was easy enough.

This inner control arm bushing isn’t visible on the Fusion until you remove the control arm. This was the rear of two control arms that car is blessed with on each side.

That Fusion reminded me of another vehicle, a 2012 MKZ that came in with an alternator you could hear whining from 100 feet away. She had been to a tire shop complaining about a noise, and the first guy who rode with her at that shop said he thought the noise was a hub bearing, but the more experienced mechanic said, “no, that’s the alternator,” because it was making the noise when the car was sitting still and the pitch of it matched engine speed. When I heard it, I agreed with the older guy’s prognosis. That alternator was making a LOT of noise that changed with throttle.

Getting the alternator off a 2012 MKZ isn’t for wimps — the refrigerant has to be recovered and the A/C compressor has to be removed, and the alternator comes out the bottom. There’s nothing easy about any of that job, but my guy got it done. I knew this 17-year-old could handle it — he had just finished replacing the heater core in a 2010 Wrangler, and after that extremely difficult job, this one was a cake walk.

The new alternator didn’t whine — the car sounded normal under the hood now, but it did have what sounded like a noisy hub bearing on the right front at road speed. It was one of those situations where the customer didn’t believe she had needed the alternator to begin with, because she was still hearing a noise on the road and one noise was masking the other. She chose to drive the car for a few days but came back and claimed the car had “put her down” and implied that it was our fault for replacing the alternator.

Here was another needful repair. The customer on this one was complaining of a vibration with the blower on high – easy to figure out and easy to fix, but needful all the same.

“I left it running when I got here,” she told me, and then said, “I had to jump it off this morning and then I drove it here (15 miles). It wasn’t giving that problem before you replaced my alternator.”

I had her pull it into the shop. I carefully explained that if the alternator wasn’t charging, the engine would have died as soon as the jumper cables were removed. Then I switched the car off and tried to restart it, but the battery was too weak. When I jumped it off and connected the Snap-on tester I showed her that the alternator was indeed charging and suggested that she find a cool place to rest while I did some more troubleshooting to figure out what was going on, but I told her I’d need the rest of the morning to be sure of what was going on.

“There was nothing wrong with my battery,” she snipped. “We’ll get to the bottom of this,” I told her.

After she walked away, I put a good stiff charge on the battery with a heavy-duty charger, then I got out the $1,700 Midtronics unit I bought from Joey Henrichs and ran through the entire routine, which records everything, including battery health and alternator ripple, printing it out for the customer. The MKZ showed a clean bill of health all the way around except for the battery.

Taking it a step further, I did a parasitic drain test, connecting a meter in series with the battery and waiting until all the modules finished charging their stuff. End of story — there was no drain, only a weak battery.

When she came back I showed her the results and told her she’d need to get the hub bearing noise handled at the tire shop. Sometimes it’s best to send some customers down the road, so that’s what I did.

Another Silverado

This 2003 1500 5.3L came to us with an overheating complaint — the guy said another shop claimed it must be a blown head gasket, but I explained that we wanted to diagnose it ourselves before we did any unnecessary surgery. Sure enough, it was overheating, but it was happening slowly, and there was no quick pressure buildup in the cooling system when the engine was started. The fan kicked on at 228 but the engine kept getting hotter until the fans kicked on high, and all that took a while, but I noticed that the radiator was still cool.

Here’s the overheating Silverado. Even with the radiator removed and bypassed and the thermostat gutted there was no flow through the hose.  Presumably this was a water pump problem?

“Let’s try a thermostat,” I told my guy. Cheap and easy comes first. We put one of those in there and burped it out, but nothing changed. The radiator was cool, but the engine was getting hot.  So I had him pull the water pump, and the borescope didn’t show anything wrong down in the pump, so we reinstalled it. With the radiator removed (no external clogging seen) I bypassed the radiator using the long hose, and we also looped out the transmission cooler lines and took the guts out of the old thermostat to allow free flow. With the engine running we had to squeeze the hose in the middle to neutralize the natural kink so as to facilitate flow but even with that hose in place of the radiator, there was still no flow through the hose, which was only warm on the ends — not in the middle. And the engine continued to try and run hot. What madness was this? If coolant had been flowing, the hose would have been hot its entire length.

Here’s the Silverado’s water pump with the rear cover removed, but I couldn’t see a problem, nor could I feel one manipulating the pulley and holding the impeller.

This was one of those exhaust bolts that had rust-melted from a 15mm down to something just a little larger than a 9/16, and it wasn’t in an easy place to access. We air-hammered this wiggler onto the bolt to get it out. It was a needful thing, but getting the bolt separated from the socket was tough.

To make a long story short, a radiator and a water pump fixed that one. Mission accomplished, but I couldn’t figure out what was at the root of this problem — I thought that plastic impeller might have been spinning on the shaft, but water pump forensics didn’t show that to be the case. One way or another, the truck never runs over 210 degrees now. Happy customer.

Article Details

Fri, 12/01/2017 (All day)

Richard McCuistian

<p>Every job isn&rsquo;t interesting, but in our line of work, challenges are the spice of life, and it feels good to be a problem-solver. It feels even better to be appreciated, and usually we are, but that isn&rsquo;t always the case.</p>

<p>auto repair, Silverado, Suburban</p>

Years ago we troubleshot a Grand Prix that had run just fine until the owner’s cousin had changed the intake manifold gasket and afterwards it was skipping dead on cylinder 2, so she asked if we could have a look at it. This was an engine skip – how hard could it be? First, we checked the obvious stuff (spark plug, compression, etc.) and came up short. But what we did find was that the number 2 injector didn’t sound right with the stethoscope, so we replaced that injector with a known good one, but to no avail. We then checked the entire injector circuit for shorts of any kind and excessive resistance, pin fit at the ECM and the injector, current flow through that circuit with the injector artificially energized (0.8 amps) and ran a temporary circuit overlay. Nothing changed.

When I finally scoped the injector pulse and compared it to the others, the pulse was strangely narrow, so I called a local salvage yard and obtained a replacement ECM. No cigar. Not even close. I replaced that ECM with a second one, because the salvage yard had a bunch of them on hand and they were only $20 each. I double checked everything. This made no sense at all. Finally, I Scotch-locked that injector’s trigger wire to the adjacent injector’s trigger and the car ran great from then on with no more problems. Remember, this was an OBDI system.

I didn’t like that temporary fix, but one of the GM engineers who was as stumped as I was told me those early GM ECM injector drivers can each handle 4 amps, and it’d be just fine carrying two 0.8 amp nozzles. Even if it had burned out a driver and I needed to keep digging, I still had two other good ECMs on hand. One way or another, that Grand Prix holds the distinction of being a grueling fueling enigma that still has me wondering to this day.

Burning in bad info

In the world of politics, news media and other sensitive areas, some have discovered that you can repeat some supposed fact enough that most of the hearers begin to believe it, regardless of its veracity. Our customers – some of them anyway – can also convince themselves that they know what’s wrong when they have little or no useful data except the symptom. Then there are those who have a vehicle concern and somebody they know who seems to have a bit of automotive knowledge makes a superficial jackrabbit diagnosis, hopping quickly across the high points without doing much else. And don’t you love those customers who bring you some parts they want installed based on an offhand diagnosis made by somebody who either doesn’t know how to do the work or “doesn’t have time?”

Even when we begin to gather data scientifically, we can still misfire on our diagnosis, and anybody who claims they haven’t been there isn’t being truthful. For just one example among many, I would have sworn in a court of law that the left rear axle bearing was ruined on my aunt’s ‘92 Crown Vic – after all, that’s where the noise seemed to be coming from, and it changed for the worse with a swerve to the right – as it turned out, she had a noisy left front tire and for some reason the noise was telegraphing to the left rear.

Back in the early ’80s a guy wanted me to replace his carburetor because two different shops using offhand diagnostics told him they didn’t do carburetor work, but that it needed replacing. One of them even claimed to have used an ignition scope and was a tune-up shop. It was a small carburetor on an inline six, so first, I bought a $6 Delco carb kit before I did anything else. Afterwards, I did a mild throttle snap and found it dropping a cylinder under load. I identified the cylinder, replaced a bad brand-new spark plug, and fixed that one.

And then there are quite a lot of people who will play the blown head gasket card without having seen anything other than an overheating issue. I don’t know how many times I’ve heard that, and I experienced it once myself on a 1993 Camry I checked for a friend beside the road. That one had split its radiator, overheated and was puking hot, sweet-smelling geysers out of the filler neck when we refilled it and fired it up. After it came to the shop on the hook, I wanted to show the class how that kind of head gasket failure looks and smells, but all those symptoms were gone – all it needed was a radiator. Go figure.

I have a 1989 Ford Bronco that was donated because the owner believed the head gasket was blown, but it was running crappy and puking coolant out the neck because it was a 5.8L, and he had wired it up using an old 5.0L firing order. When we wired it up with the right firing order, all the filler neck geysers went away.

A few years ago, we checked a 2.4L Dodge Stratus with a horrible oil leak that a shop had pegged as a rear main seal (how many offhand rear main seal diagnoses have we seen?) and used dye to find it coming from under the corner of the head.

Those of us who teach for a living know from experience that people who already believe they have all the facts are kind of difficult to convince otherwise.

2011 Chevy HHR 2.2L Ecotec

Bearing bad news

The owner of a 2011 Chevy HHR, 22L Ecotec with 123,598 miles had spent some time and money doing his own offhand diagnosis trying to get it started – he had checked the fuel pressure with a rented gauge, replaced the fuel pump and fiddled around some with a scan tool before realizing that he was in over his head. The HHR been sitting for a few months when it came in on a trailer. They had determined that it had to be something simple and were hoping we could get it going for just a few bucks. Somebody had postulated that it might have a bad crank sensor, and they brought it to us with the hope that we’d find out it was something simple. Well, it wasn’t. This one spun with very uneven compression, and when we removed the valve cover, we found some broken roller rockers, which typically means valves had contacted pistons, usually the result of timing component failure. But the timing chain was nice and tight, and looking down into the chain area I didn’t see any looseness or shattered sliders. Could it have been over-revved enough to float a valve? We didn’t do exploratory surgery, but we sold them on the idea of replacing the bad engine with a good used one.

When we pulled the valve cover on the HHR, we found several broken roller rockers. Something catastrophic happened here, so we decided to stuff a used engine in it.

The salvage yard sent an engine for that one with a few minor differences – the fuel rail had a different shape, along with a couple milder changes. When we were done, that one ran like a top and when we fixed an A/C leak and juiced up the icebox, it even had cold air.

The Expedition and the Crown Vic

A very regular customer brought her 2001 Expedition to us with a nasty coolant leak – this one’s a Triton and they tend to protect themselves from engine damage, but she just kept driving it. The water pipe that travels through the valley under the intake had rusted through and was dumping water almost as fast as you could pour it in. Initially we just removed the intake manifold, cut the rusted-through portion of that pipe out and replaced it with a hose and some clamps along with a new intake, but when we filled it with coolant, put a new thermostat in it and started warming it up, the warming never stopped – pressure was building very rapidly throughout the system and it was evident that this one had indeed blown a gasket.        

She’s a hands-on shopper, so she did her own search for a replacement engine at a price she liked, found one somewhere in Florida, and had it delivered to the shop. It had the heat pucks in some of the expansion plugs and so I knew it came from a reasonably savvy salvage yard. I crossed my fingers, hoping they didn’t turn the engine backwards while removing the torque converter bolts! Sometimes that flips one out of time.

Since I had people doing transmissions this time around, we went ahead and jerked the transmission out first, then I had another guy remove the original engine, and we carried it on the hoist over to the area where we do component swaps.  One of the first things we noticed was the narrow pulleys on the replacement engine – apparently this one had come from a Crown Victoria or a Town Car, but I couldn’t be sure. Oddly enough, a power steering pump came with the replacement engine, and so we took that narrow pulley and put it on the Expedition’s PS pump. We also replaced the idler and the belt tensioner, because those wide ones wouldn’t work on the replacement engine’s timing cover – and we weren’t about to swap out the timing cover if we could get out of it.

Initially, the guy who put the engine in the Expedition had put the generator wire on the top post at the solenoid, and that kept the starter energized when the generator was trying to work. The starter was a casualty in this case, but it’s an easy mistake for a beginner to make. The bottom photo shows the naked grooves in the generator pulley – the A/C compressor had the same issue, but we swapped out the power steering pump pulley to have the right one.

There were some other minor differences, but at the end, that engine was sitting in the frame with a new belt and everything plugged in, and the transmission was reinstalled – having drained the transmission and replaced the filter, we needed to start it up to get all the fluid back in the gearbox. We started with five quarts and hit the key.

When we started the engine to finish refilling the trans, we noticed that it had a large vacuum leak, and we also heard strange noises and smelled something burning – never a good sign, and it wasn’t the oil smoke from exhaust manifold handprints, either. As it turned out, the guy who replaced the engine did everything right except that he made one very easy mistake. He connected the alternator charge wire at the starter relay to the wrong post, which delivered alternator output current to the starter solenoid circuit while the engine was running, and that kept the starter energized, which destroyed the starter. Thankfully, it didn’t destroy anything else. But with that heavy rubber sleeve on the wires leaving the solenoid, it was easy to make that mistake if you weren’t ultra-familiar with the wiring.

This was another easy mistake to make – put a bolt that’s just a little too long in one of these and you’ve ruined a gas tank. We used the bolts and the gasket that came with the new tank, and so this leak really surprised us – even more so when we found out the new pump was faulty.

The 2003 Crown Vic ran out of gas while the gauge was reading a half tank. We replaced the sending unit with a new one from Carquest, and the guy who did the job used one bolt that was a bit too long when installing the pump, and punctured the gas tank. We got a new replacement tank, but after it was filled with gas, the leak was worse than ever. But that leak wasn’t around the gasket, it was around the plastic grommet where the wires pass through the mounting plate – I have not seen that before. Anyway, all’s well that ends well, and there was no fire. Only a bit of wasted gas.

The Xterra

The 2001 Xterra came to us with the concern that it had quit in a parking lot and failed to start, and somebody’s offhand diagnosis was that it had jumped time. This is a dicey situation, because that one isn’t a free-spinner, but even on interference engines, a timing belt can slip enough to stop the engine without valves kissing pistons. Had that happened on this one? I asked her if she had tried to re-start it (of course she had), but she told me she had only tried once and was hoping there was no damage. We didn’t want to do a lot of engine spinning on this one in the bay for fear of possibly making a simple no-start into something worse, so we checked the timing marks first.

On this one you can pull the upper part of the timing cover, slowly turn the engine with a breaker bar (feeling for interference) until the cam gear marks line up, and then check the crank pulley for zero alignment. Well, when we did that, we found that the Xterra had NOT jumped time. We did decide to do a timing belt and a water pump while we were there, so we bought the kit, and when we got the bottom part of the timing cover off, we found that the front crank seal was leaking – no surprise on a high miler like this one.

Putting the new crank seal in was something of a demanding process – we tried a few tricks, all of which unseated the garter spring and tried to roll the lip. I kept thinking of transmission seal protectors and how I could fabricate one for this job. Finally, I fetched a soft red plastic hole plug that had been protecting one of the ports on the 2011 HHR’s replacement engine and modified the plug with my pocketknife, making a seal protector for the Xterra front crank seal that worked so well I should have patented it.

The actual cause for the customer’s concern was deep in the distributor – it’d spark and then it wouldn’t and vice versa. We didn’t want to take a chance on that kind of “maybe,” so this one also got a brand new one.

At the end of that job, we found the real reason for that no-start. The spark coming out of that distributor was a come-and-go event. We got no spark from the towers, and so, with the cap off, we checked it at the coil. On the first spin, there was no spark – on the second spin, spark was popping there, and so we reinstalled the cap and the engine fired up and ran like new.

Unwilling to trust that come-and-go spark, we replaced the distributor with a reman unit. Now she has a new timing belt, crank seal, water pump and distributor.  Maybe that Xterra will be good for a while.

Article Details

Mon, 01/01/2018 (All day)

Richard McCuistian

<p>Some people will almost always believe a half-baked diagnosis, and some mistakes are very easily made.</p>

<p>auto repair, diagnosis, Xterra</p>

I’ve encountered many a sweeping change in my 40 years of automotive experience, and I’ve heard complaints from both sides of the service aisle about why manufacturers think they have to keep changing things instead of leaving well enough alone. Well, as I used to tell the old timers, we could still be riding horses and rowing boats, I reckon. They complained about the move from contact points to electronic ignition, carburetors to fuel injection, and so on.  Granted, there are some elements of our vehicles that seem to have been changed for the sake of change. Modules now take requests from switches and energize loads through relays, and many of those relays are now being integrated into the modules instead of being individually replaceable, which makes repairs unnecessarily expensive. For one example among hundreds, the fuse panel/junction box on a 2006 Sonata costs about $700 and contains several integral relays. And then there are those eggshell fragile “smart” junction boxes. The only piece of 21st century technology on my 100,000-mile 2007 Ford Taurus is the smart junction box, and it holds the distinction of being the only part of the vehicle that has ever given me any trouble.

Some of these “smart” boxes have labels stating that the module has to be replaced if it’s dropped from more than 20 centimeters. Networking abounds, and not only within the vehicle’s perimeter; nowadays when you pull your late-model car into the garage it may ask to connect to your home’s WIFI, and just about everybody has heard about the very troubling experiment where a couple of hackers were able to drive that Jeep into the ditch after having hacked its internet connection and taken control away from the driver.

All that being said, these sweeping changes will keep on sweeping, but people are still driving older cars that pre-date these changes, and those cars still need fixing. The good thing about the moderately older cars is that a lot of technicians have left digital bread crumbs in iATN and Identifix pointing us in the right direction, and there are TSBs that provide short cuts to some solutions that might otherwise take hours to troubleshoot. Newer platforms and those that are sparsely represented in the market have fewer recorded repairs, and they may require the technician to plow some new ground. To be frank, we can discover that we’ve been dreadfully spoiled by the databases and find ourselves troubled and plowing new ground if we can’t find a silver bullet among the posts.

Handling help requests

I get quite a few emails through my website asking for advice, and I sometimes get phone calls from shop owners and family members that live in other states. I wish I could say I have all the answers, and I try to answer the emails quickly, but there are times when the person making the request doesn’t give enough information and there are other times when I simply don’t have an answer for them. Sometimes the help request is super sparse, like those doggone work orders I used to get when I was at the dealer where the service advisor put the words “Runs rough” on the repair line and the car would perform just fine when I drove it, and then I’d discover the owner was talking about a mild tire balance concern at a certain speed on a certain stretch of road.

Sometimes, however, a savvy vehicle owner will articulate his or her concern very well and emails will be exchanged that bear fruit. For one example among many, I had an email exchange that went this way, and it had a happy ending:

"My car has started to hum at certain speeds. It's an automatic, but when it's in fourth gear, it starts to hum. Do you know what this could be?" Joe asked.

"What make, model, and year car is it?" I replied.

"It’s a Mazda 6 sedan, 2005. It hums when I'm up to 40 or 4th gear,” Joe said.

"Does it change with throttle angle or vehicle speed (remaining in 4th)? I asked.

"Yes, if I go past 40 it will start to hum pretty loudly.” 

"If you swerve gently back and forth does the humming get quieter or stop? If so, it's probably a hub bearing." I wrote.

"You are amazing! I found it was the hub bearing. I went to a mechanic who tried to take advantage of me, and I was able to break down the symptoms and possible issue. He suddenly took me seriously.  Thanks again!” Joe said.        

This is the Camry, family dog, kid in the backgound, etc., parked in my son's driveway in Georgia.

I once heard somebody say that the MIL light is the most reliable part of his or her car—it always works. I wish I had a nickel for every car or truck I've seen with the MIL light hiding behind a family photo or piece of tape. I've actually known of older mechanics (years ago) that would purposefully render the light inoperative because they were tired of it turning on and turning up like a bad penny.

This is a rather familiar kind of exchange – more than a few people email me with car trouble before they even take the problem to a shop, because they’ve been burned before and they’re trying to insulate themselves against being fleeced by a misdiagnosis or an unnecessary upsell. And while we know that not every shop is prone to try and take advantage of people, just about everybody reading these words knows that there are too many shops out there that don’t repair the problem and leave customers frustrated and angry. The other side of the coin is that there are some customers who are treated right that sometimes leave shop owners just as frustrated and angry because we all know that the customer is not always right. Sometimes they’re dead wrong and just want something for nothing. The magic is in being objective enough to know the difference between when we’re wrong and when they’re wrong, and our bottom line can be a strong motivator, but our good name is worth more than just about anything else we own. Sometimes it’s best to bite the bullet and satisfy the customer, because they will talk trash about you if they believe you did them wrong, even if it’s a gray area.

A call for the calf rope

This story begins with a help request from my youngest son Luke, who lives six hours away, is married with kids, and works as a computer network specialist for a very large company. Vehicles aren’t his area of expertise, but he’s a quick study and never quits working on something until he gets it fixed. To begin with, his Camry’s water pump locked up and destroyed the timing belt, but the 2.2L belt engine is a free-spinner, and so he had a wrench-smart friend replace the water pump and timing belt, but when his friend was turning the engine through by hand to check for proper timing after replacing the belt, it would reach a lock point like the piston was making contact with something.

“I’m going to have to pull the head,” he told Luke, “apparently it has bent some valves.” My son remembered hearing me say that it was a free-spinning engine and so he put his friend on the phone with me.

“That engine doesn’t bend valves,” I told him. “You’ve got something on the head of a piston.”

“Well, in that case I need to pull the head anyway,” his friend replied, and I agreed. He did, and found some of that powdery carbon had broken loose and piled up of the head of a piston, and that’s what was stopping the engine when he was turning it by hand.

The head was re-worked, the crud was cleaned, the gaskets were scraped, the head was reinstalled, and the engine began to breathe fire again, but the MIL almost immediately illuminated and while there wasn’t any black smoke, the gas mileage was in toilet territory, which defeated the purpose of getting this 16-year-old Camry back on the road. A code P0125 was set (engine too cold for closed loop), and the data stream scan revealed engine temps south of 160, so Luke replaced the thermostat and cleared the code, which immediately returned. He called me and said everybody he was talking to in his neck of the woods – including his mechanic friend – said the new thermostat had to be at fault, and the engine was indeed running only slightly warmer than it had previously. I’ve personally had to install three thermostats to get one good one, so I agreed. I wasn’t there to look at the rest of the data stream, but this code needed to be addressed before anything else was done. He went through a couple more Chinese-made parts store thermostats and then paid $25 for a really good one from Toyota, and while the engine temp was now hovering just above 200 degrees, the code kept returning. Remember, all this back and forth was happening via phone calls and photos sent via text message.

Since we know this connector is H3, we can find the pinout in the shop manual, and using the schematics we can determine which pin(s) need to be our focus.	In this case, simply turning over the connector caused the brown E1 wire to disengage from the connector shell. This was the cause of the P0125, which usually means the engine is running too cold, but not on Toyotas of this vintage. A kissing cousin of the P0125 is the nearly as popular P0128 code.

At that point I decided to punch the Camry into Identifix and discovered something I hadn’t encountered before — that some Toyotas of that vintage would throw the P0125 if for ANY reason the engine didn’t drop into closed loop – and that the majority of posted fixes revolved around replacing the “A/F sensor.” Obviously, if the sensor never comes alive, closed loop is a faraway dream, even with a warm engine, but the Toyota’s algorithms weren’t flagging any kind of O2 code, thus the confusion. This information is also briefly stated in the Toyota shop manual.

The Identifix post we perused in detail says, "Check the heater resistance of the A/F ratio sensor. It should have between 0.8 and 1.4 ohms,” which is just peachy if you’re working on a California car, but this one is a federal emission standard vehicle (I researched this afterward), and so when we found 13 ohms heater resistance, a new sensor was purchased – and Luke’s digital multimeter indicated that the new sensor’s heater resistance was almost the same as the old one. Quite predictably, the code returned.

At this point I told Luke we needed to make sure voltage and current were available at the sensor. I like to take an old sensor, clip the connector off, and wire a small low impedance light bulb into the O2 heater circuit in place of the sensor. Yeah, I know that most automotive instructors are terrified of even a low impedance test light, but I raked that rule off the table the first time a digital meter told me a voltage lie and caused me a couple of hours of work. At any rate, there was no voltage at all being delivered at the O2 connector with the key on OR the engine running. Now we were getting somewhere.

When you think you know

As with any circuit, understanding this one is important. Like most heater circuits, this one is hard-wired to power and receives its ground from the PCM, which typically keeps a close check on how much amperage the sensor is drawing.  Let me also say here that in the late ‘90s, Toyota didn’t believe in putting circuit numbers or wire size tags on a schematic – all they put next to a wire is its color, and that can be annoying when you’re clicking from one schematic to the next looking for sources of voltage. The colorful wire trails and pin assignments are troublesome as well (see illustration).

With the connector in hand and my help, Luke identified the proper cavities at the harness connector, and we assayed to determine whether it was the ground or the power that was missing – as it turned out, one of the wires was broken right where it passes through the seal and goes into the connector to its terminal – but it was somewhat stealthy in the way it manifested itself. At first blush, a look at the place where the wires go into the connector seal looked just fine, but as the connector was rolled in his fingers, the broken wire pulled out, and we had hit pay dirt.

The brown wire on the schematic and in the photo is reference ground for the O2 sensor element, but has nothing to do with the heater. This broken wire was obviously the cause of the P0125 – since PCM is watching the voltage in relation to this ground and it wasn’t there, the O2 was flat as far as the PCM was concerned. Usually if you measure O2 voltage live on a groundless sensor you’ll see something that looks really high, like 2-3 volts, but the PCM won’t be able to see any voltage at all. And so Luke and his wrench-smart friend set about to make repairs – with butt connectors (face palm) and a pigtail they got from somewhere – the next thing that happened was a no-start, which brought another phone call, and I managed to vector them in to the right fuse, which turned out to be the fuse that feeds the EFI relay. With the replacement of that fuse, the no-start was handled, but the first time Luke drove the car to work the MIL returned, and when he got around to retrieving the DTC he discovered a P0135, which indicates that the O2 sensor heater is either pulling too much current or not enough.

This time he found a bad butt splice on the black/yellow wire that feeds the heater, thus the P0135. Once he got that straightened out, the MIL was gone and the gas mileage had returned.

It was a twisted path and everybody involved came out a little smarter on the other end.  I just wish we could get rid of those butt connectors.   

The draftsman who drew the color-wird schematic moved the pins around on the empty white box representation of the sensor to minimize wire-crossing on his drawing, but the innards of the sensor are revealed on the O2 specific schematic in that part of the shop manual.	This was the blown fuse that killed the car after all the butt-connecting was done.	I'm a solder and heat-shrink man and I teach my students to fix wires that way. Butt when you're working in the driveway on your own car and you do computer networking for a living, you call this an "improper termination point" and you fix it the best way you know how, which, as we see here, turned out to be less than reliable the first time around. The car is running without an MIL, but I hate butt connectors and always have.

Article Details

Thu, 12/10/2015 (All day)

Richard McCuistian

<p>When the MIL keeps coming back.</p>

Whenever somebody wants us to apply our expertise to give them peace of mind, it would be nice if we were able to offer a 100 percent guarantee, but no matter how good we think we are, time and chance can always get the upper hand. About 30 years ago, a relative of mine brought me his early 80s VW Rabbit for an inspection – he was taking it on a fairly long trip, and so I gave it the once over. I did most all of the maintenance on this vehicle, so I had carnal knowledge of the car, and I could find nothing wrong with it on my inspection.

While he was on his trip, the alternator died, and a shop down in Florida charged him $300 to diagnose and replace it, which was highway robbery in those days. When he returned from the trip, he chastised me because I didn’t tell him the alternator was going to fail. Yeah, I know. I rolled my eyes too. I suppose if I had replaced the alternator, the starter, the battery, and who knows what all else, I could have averted the breakdown, but at what cost?

I remember my dad telling me about a very demanding elderly widow who came to his shop and told him she wanted him to do a comprehensive inspection of her vehicle every month and she would pay him generously each time. She then told him that if he agreed, anything that ever went wrong with her car would be 100 percent his fault and she would expect it to be repaired free of charge. He refused to even touch her car, and sent her on her way in search of a sucker, which he wasn’t. Gotta love those folks who want us to “own” all of their future problems, right?

This Jeep is the customer's primary ride, and she had been putting up with the supposed "brake pulsation" for quite a while.

Recently, a young woman who is just beginning her adult life brought a vehicle to me so I could “look it over” to see what I thought of it before she bought it. I’m always kind of nervous in situations like this, because a used car is, after all, a used car, and we all know that no inspection we can do for free goes deep enough to give a 100 percent guarantee of anything.

In this case, I checked all the fluid levels, perused it above and below for leaks of any kind, checked the age, pressure and condition of the tires, examined brakes and suspension parts, all of which looked fine, but I had to kill a large and healthy brown widow spider that had webbed the area just inside the right rear wheel and was waiting for a kill. There wasn’t much rust on the non-coated undercar components, so this car must have spent its life away from the coast and far enough south to avoid salt. I was most concerned about the timing belt, because that 2.7L isn’t a free-spinning engine, and with just over 100K on the clock, I decided to remove the upper part of the cover to have a look. Yeah, I know it’s usually difficult to look at a timing belt and say for sure how old it is, but this one had bright white part numbers on it and there was even a sticker on the shock tower proudly announcing the recent mileage at which the timing belt had been replaced. That put my timing belt fears to rest, and after checking for obvious electrical problems, I rounded out my inspection with a rubber stamp. The car seemed fine as far as I could tell

A shop in town had replaced the park brake cables on this Miata, but the park brakes wouldn't stay adjusted. What the cable replacer didn't know was that this adjustment screw (normally hidden by a cover bolt) would adjust the park brakes the right way. We made the adjustment, but I told the Miata owner that we might have to adjust it again if the brakes got loose again.

She thanked me for the free inspection, bought the car, and drove it for about two weeks, and then one day I was at lunch when she called to tell me that the engine had stopped running, and that she had coasted off to the side of the road. As I questioned her about it over the phone, she said the engine would spin but wouldn’t start. I told her we’d get the car to the shop after lunch and have a look at it.

Her folks decided to take it to a shop they liked to use (I do not know this shop or the man who runs it), and after changing a couple of parts and charging them a Ben Franklin or two for those fruitless attempts, he pulled the entire timing cover and said pieces of an old timing belt were trapped in there and had caused damage to the wiring. Then a couple of days later she told me he had called to say that the engine was locked up and he wanted eleven more Ben Franklins to replace it.

Busy times

My people are predictably happy when we have plenty of work. This time around it’s transmissions, brakes and steering/suspension, and we’ve had quite a lot of it. I had a couple of guys doing a go-through on a 4L60E as a bench job just for the experience of tearing it down and reassembling it, then I surprised them by having them stuff it in a 2001 Chevy trainer truck we have on hand just to see if it’d pull. It didn’t, and all the pressures were low. They ran some tests before reinstalling the original transmission with the notion that they’d tear down and re-evaluate the one that didn’t work. We also had a 2004 Dodge Stratus with an incorrect gear ratio in 3^rd gear code, and that one’s still under way – it performed okay on the test drive except for a chatter on the 1-2 shift, so it’s coming back out to tear down and re-check for proper assembly.

The Durango's headlamp wasn't as straightforward as the owner had imaginied it would be. The module was sending voltage out to the light intermittently—it had an internal fault. We ordered a replacement module from Ebay, but there is no 100% guarantee it will be a good one.

We’ve done enough brake jobs over the past few weeks to fill my “old brake pads” bucket to capacity, and wheel alignments have been numerous and instructive. We’ve replaced multiple sets of ball joints, steering racks, pumps, leaking lines and even a front differential chunk. We had a park brake problem on a ‘91 cream puff Miata – the brake cables had been replaced by a shop in another town, but the park brakes kept getting loose, so we adjusted them the right way. We had the red ’71 Eldorado convertible back in the shop with a steering pull and a pop noise when backing up that turned out to be worn idler arm.

Then there was the wild card – a Dodge Durango that was shifting erratically and had one headlight that was going off at random – and it was off most of the time. The customer brought us a headlight connector, because when he replaced the bulb the problem remained. A simple transmission service took care of the erratic shift, and the headlight problem turned out to be in the BCM, which is totally responsible for the headlamps. I found him a replacement module on eBay.

The Jeep “brake” problem

Our title vehicle came in for an alignment and what the driver described as a brake pulsation that “keeps pulsating even after I let off the brakes.” That sounded kind of anomalous, but that’s how I wrote it up. She left it with us, and later that morning I grabbed one of my guys and we launched our diagnosis.

The first thing I noticed as we started it in the service bay was a really high idle. As a matter of fact, the idle was so high I wondered if the foot feed was fouled by a wrinkled up floor mat (I’ve seen that more than once). I sent my guy to fetch a scan tool, and we retrieved the DTCs and found only a P0455 – no surprise on one of these – and then proceeded to hack into the live data, where we noticed right away that the reported throttle position sensor voltage was a lot higher than the baseline minimum. That would explain the high idle.

The only DTC we got was caused by a split hose—the live data showed (at idle) this TPS voltage. Note the difference between actual voltage and the benchmark minimum.

When the PCM wakes up on most platforms, it pegs the TPS voltage at key on and tags that number as the baseline for closed throttle. On some platforms, that number is stored as a part of the adaptive memory. But on the ones that re-read it at every key on, any voltage higher than the baseline after initial start is considered part throttle for the rest of that drive cycle, and at part throttle, the IAC steps will be high, poised for dashpot function (slow return to idle so as not to stall). As long as the TPS is considered to be at part throttle, the IAC will remain that way, which makes for a fast idle on non-electronic throttle body systems, even with the throttle plate closed.

After a moment or two, and a tap on the throttle (which is almost reflexive when the idle is high like this), the idle more or less normalized, and we backed out of the shop. When we had cleared the runway, wheels up and locked, we reached cruising speed on the four lane and slowed at the first turnaround to feel the brakes. We didn’t feel a brake pulsation, but we did feel the engine laboring as the vehicle slowed – the transmission was in high gear and continued to quiver and labor – even after we let off the brake – before dropping back into low gear when we were almost stopped.

I had felt this kind of thing before on other vehicles – GM platforms, mostly – when the TCC solenoid was sticking and keeping the converter locked while the vehicle was coming to a stop. In one of those cases we did a transmission service and dumped some Sea Foam trans tune in there – and fixed that one.  In another case, we did the same thing to a 2008 Impala that was reportedly having screwball transmission issues and it fixed that one too. Sometimes the quick and easy is the smart way. Sometimes the quick way is the only way when there isn’t time for anything else.

This 1995 Honda Accord's alternator was replaced back in July for a non-charging condition. It showed up again in October for draining the battery overnight. We traced a 5-amp drain to the new alternator and ran a diode test with a cheap meter (it shouldn't read both ways). Another replacement alternator took care of the draw. We had a warranty, but no 100% guarantee that she wouldn't have to jump it off again at some later date.

In this case, with the TPS reading like it was, I reasoned that the controller might be confused enough by the faux part throttle reading to delay the downshifts, and so we sold the Jeep driver on the notion of planting a new TPS on the throttle body just to see what happened – I was convinced that it needed that anyway, and it’d be an easy beginning.

Not so easy

We obtained a replacement part from the parts store and my guy set about to remove the old one and install the new one. Well, he tried to remove the old one, anyway. He got the top screw out but couldn’t move the bottom one. We all know these screws have thread locker on them and can be tough sometimes. GM Instructor Ellen Smith mentioned this annoyance in the CCC school I attended in 1981, suggesting the use of a soldering iron on the stubborn ones. We initially tried that strategy, but this one was ridiculously tough and destroyed two Torx bits, so we removed the throttle body and carefully mounted it in a vise. Nothing would move it, not even a good pair of Vise Grips. Sometimes even the easiest job can turn into a “monsta,” and this was an extremely defiant little fastener. We heated the boss with a bottle torch and continued to tighten the Vise Grips to the sides of that domed screw head, but it still wouldn’t turn.  We then ground the head off with an abrasive cutter and removed the sensor to expose the screw shaft in hopes of getting a better grip, but it still wouldn’t move – it was one with the throttle body. This was getting stupid.

Back to the Jeep—this little TPS scew was surprisingly tough to get out. Early on, a pocket lighter had been used to heat the boss, then a bottle torch, and finally, a heat gun melted the thread locking compound enough so we could rock the cadaver of this bolt back and forth and finally get it out of its hole. The TPS took care of the high idle and the transmission's delayed downshift.

Finally, I put away the bottle torch and hit the boss with a heat gun on high for about two minutes while applying Herculean pressure with the Vise Grips, and the shaft of that terribly stubborn screw finally began to turn. It amazed me to no end that the heat gun did what a blue flame wouldn’t.

With the new TP sensor installed and the throttle body re-mounted, we re-drove the car, didn’t feel anything untoward, and turned it back over to the driver. A week later she came back in for an alignment and reported that her perceived “brake pulsation” was gone. In a word, what she misidentified as a brake pulsation, we identified as an extremely late downshift, and our decision to treat the high idle/TPS problem turned out to be a surgical repair, and it felt good to get this one right the first time. And while we sometimes stumble around looking for the right fix, sensible decisions and surgical repairs are the benchmark of a true professional, but in our better moments, we all know there is no such thing as a 100 percent guarantee. This Jeep transmission fault may yet darken our door again. 

Finally, we had to work on the spark plug threads in a 6.8L van, and we had air blowing into the throttle body with the intake valve open to keep the tap cuttings from falling into the cylinder. Our problem was that, with the plug at the bottom of that deep well, we didn't know if the spark plug was seating after we fixed the threads with a tap. This is how we go our 100% guarantee that the seat was making contact. Prussian Blue is a wonderful thing to have on hand for this king of thing.

Article Details

Mon, 01/04/2016 (All day)

Richard McCuistian

<p><span style="font-size: 11.8181819915771px;">Whenever somebody wants us to apply our expertise to give them peace of mind, it would be nice if we were able to offer a 100 percent guarantee, but no matter how good we think we are, time and chance can always get the upper hand.&nbsp;</span></p>

<p>Richard McCuistian, Motor Age Garage, service repair, technical, Grand Cherokee,</p>

Richard McCuistian, a longtime Motor Age contributor with eleven ASE certifications (A1-A8, Light Vehicle Diesel, L1 Advanced Level Engine Performance, and G1), recently received recognition for his 25^th anniversary of being ASE certified. In honor of this prestigious milestone, we asked Richard to reflect on his expansive career in the service repair industry, including his passion for fixing vehicles, biggest challenges, and advice for newcomers to the industry.

Longtime Motor Age contributor Richard McCuistian holds his award for being ASE certified for over 25 years.

Motor Age:What has driven you throughout your career?

Richard McCuistian: My dad owned a shop, and from the time I was about four years old, I’ve always been drawn to grease, steel, sparks, switches, gears and bearings, hand cleaner, colorful cardboard boxes with new parts in them, and all the rest of it. I love using tools and fixing and maintaining vehicles, especially when the light bulb pops on over my head and I make the connection between the data and the fix. I like being the guy in a uniform who knows what to do when most others don’t. 

And most of all, nowadays, I love passing what I know along to the younger generation. We need new blood in this industry now more than ever, and I like being a part of that process.

Motor Age: What has been the biggest challenge you’ve faced throughout your career?

McCuistian: Like most people my age who started out forty years ago when electronic ignition was brand new and so many ignition systems were points-and-condenser, my biggest challenge throughout the years has been staying abreast of changing technologies as electronics have taken root in virtually every part of the vehicle. I spent most of my career at dealerships and got really great training there.

Now I’m teaching, so I have to make sure I stay up to date on what’s going on with the more common makes and models that populate the area where my trainees will be wrenching.

Motor Age: What is the most important advice to pass on to someone who is new to the service repair industry?

McCuistian: To begin with, you WILL earn what you get paid in this industry. After your foundational training (and it’s good to get that first), realize that speed and accuracy will be the engine and the transmission of your career. In order to get P.A.I.D., you have to exhibit Performance, a good Attitude, great Integrity, and bulletproof Dependability (hence the acronym). Once you’ve developed your troubleshooting and mechanical skills to the point that you work quickly and with accuracy, don’t think your skill level gives you a license to be a jerk. There are a lot of guys and gals out there who are better and faster than you are.

If you really want your knowledge to explode, always be willing to share what you know with others in the field. I learned early on that whenever you take the time to explain something to somebody else, you understand it even better yourself.

Secondly, realize that there isn’t a silver bullet for every problem. You have to be tough, and you have to be smart. You need to be ready to go where nobody else has gone before on a job and find the problem on your own when diagnostic tools and software don’t have the answer.

Motor Age: Why is training and ASE certification important to you?

McCuistian: Without training, you’re flying blind. Without ASE certification, you have no real credentials to show, and credentialing tells prospective employers that you’re serious about your career choice. I would not have been employable as an NATEF program instructor without ASE certifications. Further, some shops won’t even hire a technician that isn’t ASE certified. ASE certification doesn’t in and of itself mean you’re a super-wrencher, but you will command more pay as a capable and productive ASE certified student.

Richard, thank you for sharing your expertise, experience, and wisdom with Motor Age over the years and for your unceasing dedication to the service repair industry!

Article Details

Mon, 12/14/2015 (All day)

Chelsea Frey

<p>Richard McCuistian, a longtime Motor Age&nbsp;contributor with eleven ASE certifications (A1-A8, Light Vehicle Diesel, L1 Advanced Level Engine Performance, and G1), recently received recognition for his 25^th&nbsp;anniversary of being ASE certified.</p>

In my shop, it seems like we get hit pretty regularly with the ones that have been parked somewhere. A colleague of mine called me a couple of years back about a 1973 VW Beetle she had driven in high school. It was sitting in a barn on her property and she as all excited about getting it going again, because, while old Beetles used to be the cheapest car around for somebody who couldn’t do better, some folks consider them are really cool nowadays. Well, they’re not as cool as some people think they are, and to be honest, there are more than a few for sale around here that are over-priced. I probably owned a dozen VW bugs (and a Ghia or two) before I turned eighteen because my dad had a VW shop, and to me, a VW bug was something I drove when I couldn’t do any better. That being said, I had a lot of fun power sliding around dirt road curves on those back-heavy bugs and plowing through waist-deep mud bogs that would stick a four-wheel drive pickup, and dad taught me how to make a plain old VW bug run like a Porsche on a shoestring budget.

It’s no wonder they wanted this one back on the road — they even cleaned it up before they brought it to us.

Anyway, this lady I knew thought she and her husband were going to roll that old bug out of the barn, put a battery in it, run the field mice out of the glove compartment, fire it up, and drive it to the courthouse wearing a big smile. And while we’ve all heard stories of people who, with minimal effort, recovered a ride that had been sitting for years, we all know that isn’t usually the case, and I warned her that the moving parts on that barned bug would most likely be rusted together.

In spite of the fact that the bug had been parked out of the weather, she later reported to me that I was right on target. Everything except the steering box was either locked up or so stiff it could barely be moved. She was intelligent enough to shelve that project and move on. The bug wasn’t cool enough to merit the weeks or months of spare-time and rusty love it would take to get it back on the road.

I once purchased and drove a 1970 model Ford pickup from a guy who had found it sitting in a barn. He told me he had put a battery in it, got a tag for it, and drove it for a few months before he sold it to me. And I later sold it to somebody else, but it ran well, even though it looked rusty and junky.

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Back in ’72, I was at a friend’s house when his dad and his brother dragged a 1953 Ford out of his late grandmother’s garage.  This thing was covered with dust and had been sitting in there for years. Granted, the car was only 19 years old – equivalent to a ’98 model in today’s world, but we hooked a rope to the front of that old bomb, put the column-shifter in second, and dragged it down the dirt road with a pickup. It fired up and ran like brand new. My friend had just turned sixteen and thought he was looking at his first car. Wrong. His parents literally gave that car away to a relative, who sold it for junk. Go figure.

Rats and a three valve

Then there are the ones that come to us having been driven every day, but with critter damage. Rats, squirrels, and dogs can do ruinous things to a vehicle. One of my guys works at the local Ford dealer and he found critter damage on a brand new vehicle with less than five miles on the odometer – it hadn’t even been through pre-delivery, but the knock sensor harness was chewed in two under the intake manifold. I’ve found bird nests with eggs in them under the hood on a car that was driven every day, dead cats in the radiator shroud (along with a busted and out-of-balance fan), and one F150 with so much dog-tooth damage that a very thick wire harness was chewed completely in two and some of the EVAP hoses were destroyed as well. At the dealer, that was a thousand-dollar repair, and it was the work of the neighbor’s hound. If that wasn’t bad enough, the same dog got under there a few days after I repaired it and did even more damage.

This is a picture of rat damage that kept reoccurring on an Explorer we worked on a while back. It got so bad that the lady put rat poison under the hood. It got the rats, but not before they got the wires one more time.

Anybody who has done much automotive electrical work has seen animal damage to wire harnesses and hoses. This truck came to us with the “barned for years” syndrome and was also reported to have rat damage as well. It started, but all it would do was idle, and it didn’t even do that very well.

There was a “Reduced Engine Power” message displayed in the cluster, but the rat damage we found on our first pass was minimal – the only thing the rat had chewed was the knock sensor wiring. So why wouldn’t it idle? I put a guy to work figuring it out.

The three valve

In the meantime, a 2007 Expedition came wheeling in with some pretty serious misfire issues. The owner wanted the fuel pump replaced before we did anything else, and so we did that at his request, but to no avail. His reasoning was more or less like mine — we had replaced the spark plugs on this Expedition only a couple of years ago, so I was surprised to find that it needed another set, those snouty carbon-stickers are always fun. He had driven it many a mile since our first replacement. My instructions to the guy who drew that job was to get the engine good and hot and jerk the spark plugs out with an impact wrench. He did, and we got all eight plugs on the bench in no time at all. Bringing them out quickly tends to break that annoying carbon bond and works a lot better than anything else we’ve tried… and we found early on that we have absolutely nothing to lose using this method.

After we got done with the spark plugs, one of my guys was doing an inspection of the rest of the vehicle and found a leaking strut on the right rear. What was odd was that it looked like it had just started leaking while it was sitting there. Gotta love those. The owner is fixed-income retired, so he only wanted that one shock replaced.

The Trailblazer

Some jobs seem pretty simple – a 2004 Trailblazer came in with a leaky radiator and a rattling noise that turned out to be bad water pump bearings, and in the process of replacing that pump, an overzealous youngster broke one of those six-millimeter water pump bolts off in the timing cover using a 3/8 air ratchet to tighten them. Live and learn. With the radiator removed and the grille out of the way, I put him to work drilling it out (center punched first) and even with another guy helping him, all they could do was complain that the drill bits I provided weren’t getting the job done.

I cautioned them about spinning the drill bit too fast – and an air drill likes to do that – so they were relegated to using an old Makita electric 3/8 drill, but in true form, they cried and walked away. I got a stool and sat down with the same drill and the same bit they had been using and drilled far enough into what was left of that bolt so that I could snag it with a screw extractor and literally bring it out of there with my fingers. They swore I had found a better bit, but I used the same one they did. They just needed more grit.

Discovery on the reduced power

Back to the Silverado, my guy discovered that the Throttle Control Module was offline – no wonder the throttle wouldn’t move! I pondered the very existence of this module early on. Presumably, Ford adopted the faster processing Black Oak PCM before they went ETC, lagging a few years behind GM, who elected to keep the same Delphi unit and add another smart box to bring the necessary reaction time for drive-by wire. This little box takes input from the three redundant Accelerator Pedal sensors and drives the throttle plate, all the while watching the blade’s position via a redundant pair of pots. It talks to the PCM via the painfully slow UART link.

This new fuse that feeds the ETC module did a serious flash-bulb as soon as the key was switched on. (Try catching this image with your camera!)

Well, the ETC/ECM fuse was blown to smithereens in the junction box, which would explain why the ETC module was down, but when we inserted a new fuse and powered back up, the new fuse we had installed flash-bulbed. Could this be the result of rat damage we had missed on our first pass?  It seemed possible.

The ETC module is mounted between the brake booster and the fender (the yellow paint-numbers are on the salvage yard part that fixed it). We first removed the cover from the unit looking for something obvious — didn’t see anything, then we checked the pins for proper power and ground and found nothing out of the ordinary.

Schematic-reading showed one power and one ground, both of them leading to the C1 connector. Pin 15 is hard-wired to ground and pin 7 receives power from the fuse, which would immediately vaporize with the module plugged in, but would remain un-blown with the module disconnected. We found another grounded pin in the number 6 cavity, which, as it turns out, is connected to the high mount stop lamp for the purpose of canceling the cruise.  Checking pin 6 in C1 showed a ground that would go away when the brake pedal was depressed – there were no other grounds leading to the connector, and since the short went away with the box unplugged, the box had to be internally shorted. Why that happened while the truck was barned is something of a mystery.

As the schematic shows, pin 15 is ground, and pin 7 is ignition voltage. It was a simple matter to eliminate harness concerns.

I dropped by a salvage yard on the way home and snagged a used replacement module for thirty bucks. That solved the Reduced Power message and the non-responsive throttle issue, but the truck still ran awful, and we intended to find out why. Perhaps some hidden rat damage awaited after all.

As it turned out, we had a misfire on cylinder six, and a set of spark plugs didn’t change a doggone thing. The cranking compression wasn’t as strong as we would have liked on any hole; every cylinder on that 4.8L was bouncing around 120, but the non-firing one wasn’t any worse than the rest, and it never hit a lick at any speed when the engine was running. Swapping coils didn’t move the misfire – it remained on cylinder 6, and an intake smoke test revealed nothing in the way of an intake leak.

We thought of doing a running compression test but figured we’d try one more thing before we did that. It was time to do an injector flow comparison.

Using the OTC’s handy $100 Electronic Fuel Injector tester, we watched the fuel pressure on each injector during 500 1 millisecond pulses and found that the number six injector was flowing no fuel at all. Eighty dollars later the Silverado was idling and driving smoothly. The rats weren’t as much of a problem as we had originally figured they would be. They only chewed two wires on this one.

Finally, the #6 misfire had to be addressed (see top screen), and the OTC injector tester fingered the problem handily — the #6 injector was clicking normally, but not delivering fuel. After it was replaced, the misfire was gone.

Article Details

Tue, 11/29/2016 (All day)

Richard McCuistian

<p>In my shop, it seems like we get hit pretty regularly with the ones that have been parked somewhere.</p>

<p>misfire, ETC/ECM, rats</p>

Those of us who have attended manufacturer schools know full well how important the progression of a repair goes. First, the concern must be verified (if possible). The freeze frame data helps in that regard with drivability problems, because that snapshot provides what Chrysler used to call a “similar conditions window.” But then there are those problems a scan tool can’t detect, but our ears and eyeballs can. Spraying or dripping fluid leaks. Engine noises from inside and outside; whining alternators and power steering pumps; rattling or rumbling A/C compressors. Those are easy to verify, but some of them can be difficult to pinpoint.

Back in 1977 I was working at a small independent shop for a guy named Ed Davis. That shop had a concrete floor, but no lifts, and it looked like a big barn, but it was in a good location. One day a ’70 model Ford pickup came driving in the door, and it sounded for all the world like something major in the engine was about to come undone. I stood there thinking we had a major overhaul on our hands, but Ed had the owner switch the engine off, and then he took his pocketknife and cut both belts off. I noticed that one of the belts was gapped and had chunks missing, but so what? That noise was nasty – surely there was metal on metal hammering somewhere! But when the owner restarted the truck without the belts, it sounded so smooth and quiet that I absolutely couldn’t believe my ears. A new set of belts fixed that one. Since then, I’ve been smacked around a few times by one problem either imitating another or cloaking one. 

This is a nice truck — well worth the cost of an engine.

The Titan

The subject of today’s article — a 2005 Nissan Titan with 157,647 miles — hadn’t been driven for a while because the owner was certain that the engine was destroyed, and she wanted us to listen to it. She said her husband had driven it until the oil light came on and kept driving. That sounded serious, but we figured we’d evaluate it anyway. She left the truck one night after we were closed and gone and we looked at it the next morning. We initially noticed two things. First, before we even started the engine, we found that the oil wasn’t touching the stick, but it only took three quarts to put it on full, so it wasn’t low enough for engine damage, and she didn’t mention having added any oil.   

When we started the engine, it was rattling to beat the band in the bell housing area and leaking oil from the rear main so fast that it made a puddle nearly two feet in diameter within three minutes. Seldom do we see a pressure-driven leak that bad this side of a double-gasketed oil filter.

I have seen a lot of cracked flywheels, but this one took the cake for having been driven many a mile until it began radiating cracks from the bolt circle.

The noise sounded suspiciously like a cracked flywheel, but we didn’t hear anything else – that being said, how long do you want to let an engine run when it’s bleeding to death, and who could hear anything over that nasty rattling in the bell housing anyway? It was telegraphing all over the place. I called and suggested that she let us jerk the transmission out for some exploratory surgery, and she agreed. What we found was a very seriously cracked flywheel. Not only was it cracked around the bolt circle, it had cracks radiating toward the ring gear. This was a big noisemaker. A new flywheel from Nissan is only a little more than a hundred bucks, and we got her to agree to the flywheel and a rear main seal. We had also drained the transmission oil (which was kind of black), and she’d get the new red stuff too. This transmission has a metal screen that can be cleaned and reinstalled. Justin steam-cleaned the muddy transmission and the other parts in preparation for the reassembly, but the flywheel wouldn’t be in for a couple of days.

Altima engine swap   

About that time, we drew an engine swap job on a 2005 Altima that came in rattling like a diamondback, and the owner was savvy enough to have a replacement engine dropped off right after the car rolled in. Externally, the replacement mill was rusty on the steel and chalky on the aluminum - it looked like it had been sitting somewhere damp, but it turned easily with the breaker bar and there was no sludge we could see in the oil splash area through the filler cap hole, so we didn’t even yank the valve cover. It did get a rear main seal just for grins. I considered transferring the catalyst heat shield from the original engine, but those little bolts will usually snap when you try to remove them, so I left it be.

With these two grounds swinging, the Nissan would just sit there and spin, which isn’t particularly surprising. What’s worse is when the guilty ground is buried somewhere out of sight.

With everything disconnected and the powertrain sitting on the OTC lift, we decided to take the Autel scope camera and the MaxiSys we got from AE tools to have a look in the upstream O2 sensor hole at the brick, where we found at least part of the reason for the engine failure, and it’s a fairly common occurrence on these little rascals. That potential source of damage tends to be cloaked if you don’t look here. The catalyst on the bad motor looked like Bryce Canyon Utah on a moonlit night when we took our snapshot, and some of that brick dust must have made it through the remaining comb, into the EGR system, and back into the chambers. The early Ford SHO Taurus engines tended to have that problem too. Fortunately, the replacement engine’s cat had a nice healthy looking light-off honeycomb.

This was actually kind of funny – a guy down the hill who primarily does diesel nuts-and-bolts work made this connection and couldn’t figure out why it wouldn’t charge. The alternator was checked and found to be fine.

And every Altima veteran knows it’s a good idea to shove new cam and crank sensors in the used replacement engine, but we didn’t (why I still don’t know), and this time we got lucky, but at first, we didn’t think so. The replacement engine spun without fire and even showed moderate activity at the COP coils with the PICO wand, but then he found two small ground wires on the upper part of the timing cover he had left swinging, and when we got those in place we had fire in the holes, but after a few test drives we found that it would sometimes default to idle and throw TP sensor codes – it would need a throttle body – we had used the car’s original one when we sewed it up, because the on that came with the replacement engine had fallen prey to the elements and risking that one would be a bad bet. Even with a customer-supplied engine, that job wasn’t cheap at the end of the day, but today it’s back on the road.

The catalyst on the Altima was a nasty mess, and this isn’t uncommon on those vehicles. Fortunately, the replacement engine’s cat looked healthy, but a bolt-on replacement runs about $350 or so if needed.

The frozen Focus

The 2010 Focus belongs to a colleague, and her complaint was that she’d lose her air conditioning after driving awhile. One of the first things we noticed was that the suction line would become coated with ice. This was a freezer and we needed to know why. The evaporator thermistor likes to die and prevent A/C engagement on these Fusions, but could it possibly fail the other way? We had popped one in there last year, and she didn’t seem to have much trouble after that, but this past autumn the problem returned, and we broke out the IDS to see what we could see on the PID list. Measured with a thermometer, the register temperature would drop into the low twenties with the evaporator temperature reading hovering just below fifty degrees. What the heck was this all about?

The freezing evaporator was apparently blocking the airflow across the thermistor on this Fusion – it’s not in the heat exchanger like they used to be, and that created the confusion.

Let me go on record by saying that I absolutely love Identifix and wouldn’t be without it, but in this case, the I-fixers weren’t much help. A/C problems abound on Ford Fusions and it’s easy to get bogged down wading through all the posts – I put in a hotline request and the guy suggested installing a resistor in series with that NTC thermistor – higher resistance translates to a lower measured temperature. A very competent Ford tech I know suggested the same thing. Had it been done successfully before? I had no idea.

With everything sitting fallow and the control box out of the loop, the thermistor measured the right resistance for ambient temps. And while I could see the hotline guy’s logic I couldn’t figure out why it’d be necessary to add a component like that to a system that wasn’t built with it. Of course, there have been times in my career when I did stuff like that for troubleshooting purposes, and so that’s what I did this time, but nothing seemed to change. In the meantime, we also noticed that the blower was come-and-go and we had to replace the controller and its connector to take care of that problem – that’s another common malady on more than a few vehicles we saw last summer.

The Discharge sensor was what we found ourselves focusing on, but actually the easy-to-change pressure transducer was at fault – it stopped the freezing problem for good.

While we were fighting the Focus, a 2006 Pontiac G6 came in with a charging system that wouldn’t work. Well, as it turned out, somebody had worked on that one in the starter area and had connected the fuse-linked alternator charge wire to the solenoid post that fed the starter motor where nothing is supposed to be – the charge current from the alternator was never making it to the battery – it was apparently just slowly spinning the starter motor as the car was driven. That one was easy to find because there was no B+ measured at the big alternator terminal. It looked like somebody had put the charge wire on the terminal that was easiest to get to. Rookies do that sometimes.

This is the part number for the transducer on a 2010 Fusion in case you run into one of these.

My breakthrough on the Focus freezer came when Jimmie, one of my superstars at a nearby Ford dealer, ran into the same problem on a Fusion he was working on. After replacing that $20 thermistor and his Fusion still freezing up, he decided that the A/C pressure transducer was at fault (I had never seen this), and while he was ordering one for the car he was working on, I had him snag one for me. And since we changed out that $125 transducer our Fusion has had normal A/C. The part is easy to change. This cloak came from the fact that the actual temperature of the evaporator case plenum was skewed because the evaporator was freezing up and blocking airflow – rather than measuring the actual evaporator temperature the old fashioned way, the thermistor is measuring that open area, and for some reason it doesn’t read the temperature of the air that’s exiting the registers, thus this problem was cloaked by design, albeit not purposely. The IDS PID in this case wasn’t particularly friendly, nor was it helpful. One way or another, this one snowed us for a while.

Clash of the Titan

The flywheel came in for the Titan, and with the oil leak fixed and the transmission re-stabbed, it was the end of a long day. We started the engine and it didn’t leak oil and ran quietly, but we didn’t warm it up, nor did we test drive it that day. That would happen the next day, and when I spoke to the lady on the phone, I even told her that the jury was still out but that it looked like we had maybe dodged a bullet, but I told her I’d know more on the morrow. And I did.

Yeah, we should have checked this first. It was a bad call — and all mine — to go after that flywheel noise and that geyser of an oil leak. We never stop learning, it seems.

The bullet wasn’t dodged. When we started the engine the next day to test drive it, we heard a tattletale knock as soon as we dropped it in gear – and it wasn’t a good sound. Apparently, it had gone lower on oil than we had presumed, to the severe detriment of some bearings. At that point we pulled the sump pan to find two things. We found a partially clogged oil screen and slivers of engine life forces swimming in the sump. It wasn’t a good feeling, but the lady who owned the truck was surprisingly understanding – the flywheel had indeed needed replacing, but a replacement engine very probably would come with one anyway, and that 2010 truck is worth an engine. I even found her one for a good price, but she decided to put off the repair until she could feather out financially. They drove the truck away with the knock, and from what she told me, we’ll see her again when she gets an engine. It was a heck of a lot quieter and there were no oil leaks, but it still felt like we had dropped the ball – and I guess we did.

Conclusions

I was lamenting the experience with that Titan to my advisory committee, and several of them said they had experienced the same kind of pitfall – one serious problem cloaks another one to the point that the first fix isn’t the final one, and some customers are more understanding than others. And I don’t like this any more than the customer does. With 20/20 hindsight, I realized that we should have pulled the sump pan before we went after that flywheel, because it would have been easy to do, and the bad call was all mine. I suppose the vibrations from the flywheel coupled with that hard rear main seal must have been the perfect formula for making a pint-a-mile oil leak, especially with the bearing(s) hammered out. Well at least we got that oil leak fixed.

Article Details

Wed, 03/01/2017 (All day)

Richard McCuistian

<p>One serious problem cloaks another one to the point that the first fix isn&rsquo;t the final one &mdash; and some customers are more understanding than others.</p>

<p>Titan, Altima, thermistor</p>

Whenever we get a vehicle in for one simple service and find a lot of other stuff that needs attention, any well-trained, reliable technician will make a list of the needed repairs for the customer, putting the safety-related ones at the top — loose front end parts, failing brakes, expired or worn out or expired tires, and so on.  The caveat is that if a customer is shocked by a large estimate of needed repairs they didn’t expect, they’ll tell all their friends your shop tried to sell them the moon. And today, it doesn’t take many needed repairs to produce an estimate that climbs off the chart above what some customers can afford to have done. Even if they can afford the repairs, some savvy customers will opt to get a second opinion, so honesty is always key when making a list like that.

Show and tell is the best way to handle those situations. And your communication skills must peak in situations like this. Someone has quoted Einstein as having said, “If you can't explain it to a six-year-old, you don't understand it yourself.” And we all know some customers are sharper than others when it comes to absorbing what you’re telling them.

This canteen green Pathfinder hadn’t darkened our door before, but we had done numerous jobs for these folks on their other vehicles.

The other way the laundry list estimate goes is when they bring one with them when they come, and in my department, we get that regularly. These folks are typically the busy drivers who have been putting off first one repair and then another one for quite a few thousands of miles and then they’ll decide they want all those problems handled all at once. And some of their repairs aren’t quick and easy, either.

One of the recent ones we got was a 2005 F-150 with an inoperative moon roof that was stuck in the open position, no taillights, inoperative outside rearview mirrors and an erratic gas gauge. That same day we got a 2009 Chevy C2500 with a “fix whatever you find wrong” order, and there was quite a lot we had to do to that one. Then there was the 2005 Nissan Pathfinder with a laundry list that was a knuckle-busting adventure from beginning to end.

Happy customers

This family loves the work we do, and they tend to bring us most of it, but this was the first time we had ever seen the Pathfinder, which had 185,654 miles on the odometer. On the phone, the owner told me the instrument cluster was acting crazy, and I figured that’s all she wanted done initially, but then by the time her husband got there with it, she also wanted the heater core replaced – what an afterthought that was! It had long ago been bypassed.

As for the instrument cluster, it was doing wacky things. The temp gauge, the tach and the speedometer would come and go, and the brake, ABS and VDC warning lights would flash on and off just as randomly. The scan revealed a network code or two, but not much else. One thing we did notice is that the cluster couldn’t communicate during the dead-needle times. Filing that away mentally, I had Thomas launch into the heater core job.

In the meantime, the two other laundry-list vehicles rolled in. That 2009 2500 series Silverado mentioned earlier had been neglected for many a mile and year, with StabiliTrak and Tire Pressure Monitor messages, a gaggle of inoperative and busted lights and inoperative door locks. The 2005 F-150 was one a police officer brought in with an inoperative moon roof, tail lamps that didn’t work and a squirrely gas gauge.

The Silverado wasn’t all that interesting, except for the StabiliTrak message displayed on the cluster. The DTC and the troubleshooting led to the replacement of the steering angle sensor, which was fairly involved because of the rusty, dusty fasteners. Robert jerked the steering column out, put it in a vise, and did the surgery – that took care of the StabiliTrak. The rest of the repairs were fairly straightforward, but we did need to mount a couple of universal tag lights in the rear bumper – you can get a traffic ticket in these parts if your tag lights are out. We also replaced the busted CHMSL/Cargo lamp assembly. We replaced the driver-side power door lock switch for corrosion, but then found two of the four door-lock actuators were dead, along with two of the tire pressure monitor sensors.

The 2005 F-150’s moon roof was open and wouldn’t close (not good on rainy days), and so when we ran through the process of checking switches and wires we found a bad moon roof motor. We left the permanent magnet casing off the motor, remounted it and turned the armature with fingers to close the moon roof, because he didn’t want to spend the $300 on a motor. The issue with the gas gauge and the taillights had its roots in an oddly melted connector shell just outside the frame rail on the left side. The wires leading into the front side of that connector looked like a flame had been held under them — the tape and insulation was melted, and that side of the connector was, too. We could twist and wiggle the connector and get taillight and gas gauge normalization, and so we opted to clip that connector out and bypass every wire with solder and heat shrink. It was a good repair, because even if we were to find new replacement connector shells for this, they’d be too expensive.

On the 2005 F-150, this oddball melting almost looked like somebody had built a fire under it at some point – when we wiggled it, the tail lights and the gas gauge would go nuts, so we removed the connector and made the harnesses one at that point.

A patch job and a no-fueler

One of our directors owns a fairly decent little 2001 Tacoma he uses for deer hunting, and he came to me one day because he was having to add a gallon of water a week to keep the cooling system filled. It turned out that the coolant was making its way into one of the cylinders and out the tailpipe — one of the spark plugs was ultra-rusted. He made it plain that he didn’t want to start with a head job on that deer hunting truck, and so he asked if I had any other ideas. For his purposes, we decided to run some head gasket sealer through it, carefully following the instructions on the bottle for time, then we refilled it with coolant mix. About a month later he came by and told me that he hadn’t had to add any more water. Take that for what it’s worth.  When somebody’s in a bind, we do what they ask if it’s not dangerous.

This was the rusty plug from the Toyota Tacoma that fingered the cylinder head gasket as the cause of coolant loss. The liquid head gasket sealer paid off on this one. We’ll see how long it lasts.

About that time a 1999 Lexus rolled in that wouldn’t take gas at the pump, which can be one of the most frustrating issues known to man, and we found a plugged vent hose. Some insect lost his homestead and that customer was a lot less frustrated the next time he pulled up to the pump.

Even in the south, we get seized parts, and they’re always fun to deal with. One thing we do get a lot of down here are dirt-dabber nests in annoying places – the Lexus wouldn’t take gas with this clog.

Back to the Pathfinder

With the heater core in place on the Pathfinder, Thomas came to inform me that the brittle heater pipe manifold under the hood had broken when he was reattaching the hoses to the heater core, and this wasn’t something we could fix, so we ordered the $220+ manifold with its built-in plastic water pump and did that job up right. Filling the cooling system was challenging, but with the front jacked up, we managed to make it happen.

Before we re-attacked the cluster issue, we figured we’d do the alignment, and Thomas started out with the rear wheels because we always align those first if there are adjustments. The problem was that the adjustment bolts were rusted to the bushing sleeves on one side and the first bolt he fought with popped off right below the nut, which had become an irremovable part of the bolt. This was becoming difficult and irritating beyond words.

The rear control arm adventure was quite the knucklebuster. We attempted to drill this (didn’t have a Rescue Bit® on hand), but it was pointless. We opted to engage the high speed cutter, get some replacement cam bolts, and put a new control arm on it.

I called the owner to enlighten her, and she told me the Pathfinder had found most of its early paths at the beach, because that’s where it lived for the first five years of its life. Yeah, I know you Northern wrench guys see this every day, but we aren’t used to it down here in the south, although we do see some rides from up your way now and then. We ordered replacement cam bolts from Nissan and a lower control arm from the parts store, but to get the old control arm out of there we had to use the high-speed cutter’s 4-inch wheel to clip the adjustment bolts just inside the flanges.

Got that part of the job done, finished the alignment, and then we went after the cluster. Checking the network with the Pico, we found a pattern that was somewhat noisy, but after eliminating first one module and the other to no avail, we decided the cluster itself must be at fault because sometimes it’d talk and sometimes it wouldn’t.

The Pico pattern always looked pretty much the same, so after disconnecting every module on the network (one at a time, we decided to replace the cluster and that’s all it needed to normalize the needles.

This cluster is a plug-and-play unit, and when we told the customer what we had decided, the owner found a used one for $75, and when we popped it in there everything was peachy keen.

The 2009 F-150 transmission problem

In and among all these jobs, we had a 2009 F-150 with intermittent 6R80 transmission problems. The symptom was that the truck would have spells where it wouldn’t back up and during those times it would also stick in third gear until you cleared the codes. We were told that a transmission shop had pulled the pan and found good fluid and no debris, and they were kind of stymied as to what needed to be done next, so they sewed it up and the owner brought the truck to us.

We got a Transmission Range sensor code, but that was pretty much it. In the years that I’ve done this, it’s a pretty good bet that the transmission control module (or PCM) is suspect if the transmission starts acting strange and wiping the codes clears it up for a while. This is obviously not always the case — sometimes the transmission controller will go into limp-in mode for other reasons. With zero experience on this 6R80 gearbox, I called one of my guys who does them all the time — only he’s accustomed to the newer ones. He told me we’d need the “leadframe,” because he has to change them regularly for this kind of problem. That device looks like a big hard-wire harness with the speed sensors built in, but it’s actually the Transmission Control Module. Why they call it the “leadframe” is beyond me.

This is the “leadframe” as Ford calls it that actually turns out to be the TCM.  We wound up having to replace the whole valve body on this 2009 F150 – when we first removed the valve body we found this broken adapter and replaced it. And every time, we were careful to use a torque wrench when reinstalling the valve body.

My guy decided to help out and called the parts department to ask if they had one, and then I called, gave them a purchase order, and they billed it out at $125. The way this went down was a perfect-storm situation, because the year model was lost somewhere in the process of passing information from pillar to post, and it cost us some work.

When we pulled the valve body to replace the leadframe, we saw that the plastic-and-rubber adapter between the valve body and the pump was cracked, and so I got another one of those from my guy at the Ford place. The only problem was that when we put everything back together put the fluid in, we found that the transmission wouldn’t engage at all and the TCM (leadframe) wouldn’t talk to the IDS either. But we could plug the old leadframe into the wires and let it swing and it’d talk to the tool just fine.  What was going on here?

This was strange to me — for years Ford told us that electronics couldn’t cause a no-engagement issue, but here it was. Things have obviously changed. With the absence of electronics, this one dumps the pressure instead of raising it.

It was then we discovered you can’t buy a leadframe for a 2009 model — you have to buy the whole valve body, leadframe and all ($1,000). And even though the later leadframes look identical and are replaceable separately, they won’t talk to the IDS and they won’t function on a 2009 model. So we got a whole valve body, installed and torqued it, did the fluid fill, and fixed the truck. It was messy but fun pumping transmission oil into that one through the hole where the dipstick tube used to go and checking it with that tiny plastic dipstick right next to the catalyst with the engine running and hot. That was a knuckle-BURNER. One way or another, we won that fight and all the rest of them on this round, with busted and burned knuckles galore. Who knows what we’ll see next week?

Article Details

Fri, 06/02/2017 (All day)

Richard McCuistian

<p>Whenever we get a vehicle in for one simple service and find a lot of other stuff that needs attention, any well-trained, reliable technician will make a list of the needed repairs for the customer, putting the safety-related ones at the top.</p>

<p>F-150, customers, estimate</p>

Those of us who have been in this industry a long time can remember when a vehicle was pretty much used up at the 100k mark. Odometers “rolled over” after 99,999. I read somewhere that in the 1930s, most engines needed rebuilding every 10-20K miles. Technology has certainly improved, and there are more than a few brands out there that can rack up some stratospheric odometer numbers with very few debilitating problems along the way.

When I worked at the dealer, we saw more than a few Ford pickups and Jeep Cherokees with 300-400K miles. The folks with Jeep Cherokees would keep the one they had driven hundreds of thousands of miles and buy another one. A few years back, my department was given a 1997 Pontiac Grand Prix with 250k on the clock and it still runs like a new car, even though the interior trim has aged to the point of coming apart in places.

This is one of those stealth problems — one of my guys had replaced the radiator in this high mileage Ranger, and since the lower radiator hose clamp had seemed okay, he re-used it. What he couldn’t see was that this clamp wasn’t quite long enough — the screw was only holding a couple of slots, and they gave way one day about six weeks after the radiator was replaced and dumped the coolant.

Some of the customers’ vehicles we work on in my department are low-mileage cars only a couple of years old, but we spend a fair amount of time on older ones. This time around there are several jobs to discuss; the most recent one we did yesterday. It was a high-mileage 2010 Ford Edge that had developed a serious transmission cooler leak after hitting a dog, and she had driven it until it was six quarts low on fluid before realizing that there was some serious dripping going on. As a side note, while it was on the lift, the lift itself breached a hydraulic hose and started leaking, and we had to fix that too – my contention is that that the transmission leak on the Edge was contagious. That one got a transmission cooler and the six quarts of replacement juice and the lift got $200 worth of new hydraulic hoses. Two crises dealt with in tandem.

Another recent one was a 2004 Trailblazer that rolled in with really high miles, an engine skip and a $450 estimate another shop had given her to fix that skip. They had proposed those $13 apiece Iridium spark plugs and a whole set of new coils. Well, this gal is a single mother and rejected that estimate out of hand. We pulled the codes, found a misfire on the No. 1 hole, did a compression test for good measure, then put a set of platinum plugs in there and a single coil.  For grins, we also polished the headlights, which had taken on the color and cloudy opacity that might be compared to dirty lemon juice. And yeah, we don’t charge labor, but why does a vehicle that old need the most expensive plugs and a whole set of coils? There is such a thing as pricing yourself out of a repair.

The Avalanche

The Avalanche

A lady called me one week while I was off during a break and asked if I’d have a look at a 2003 Mazda B3000 she had sitting on the curb in front of her house. The story on that one was that it was her son’s truck and that it had failed to start one night in a parking lot and they had tried to jump it off with no results. Figuring it was a bad starter, they simply parked it (strange, I know, but that’s what happened). It had been sitting there for three months when I opened the hood, noticed that the battery had been removed, connected my 30-lb. jumper cables, and fired it up. Faux jumper cable connections on crummy battery cables can de-rail a DIY diagnosis of a no-crank in short order. The B3000 ran like brand new and even had cold air, so she washed it and got it ready for a quick sale. A couple of weeks later it failed to start at the car wash, but that turned out to be a tripped inertia switch – somebody must have slammed the door or kicked it or something. But during the three months the Mazda was down, she had sold the boy her 2004 Chevy Avalanche and had bought herself a newer truck.

Now her son reported that the Avalanche, which boasted 268,587 miles, was leaking power steering fluid, and she wanted to know if we could check that out. I agreed, and when the truck arrived, we discovered that it had a dreadful engine oil leak that made the power steering leak look like a minor drip. It was odd that he was more concerned with having to add a half a pint of power steering fluid once a week than he was that the engine was bleeding oil to the point of what could be an early death. When I asked him how much engine oil he was having to add, it turned out to be a quart every two or three days. Yet the first thing on his mind was the power steering leak, probably because it’d whine and get his attention and he was tired of that. Squeaky wheel gets the grease, I suppose.

Well, we went after the oil leak first – it was dripping off the bell housing, but since that’s the lowest place, the leak might be coming from the pan gasket, the oil filter adapter or the intake. The bell housing was dry on the outside leading up to the intake, and it didn’t look like the oil pan was leaking (which these love to do). We looked closely at the oil filter housing before popping the small round cover off the underside of the bell housing, and through that hole, we found engine oil puddled in there, pointing to a rear main seal. We would attack that first, proposing the rear main, a torque converter seal and an oil pan gasket just for grins, since GM was kind enough to put a crossmember under the oil pan and make that part of it an easy fix.

My guys plowed into that one, and we were extremely happy it wasn’t one of those later model GM platforms with the stainless steel exhaust fasteners. Whoever came up with that idea should be chastised harshly. You can’t cut those stainless nuts with a torch and heating them doesn’t help either. But I digress.

The Explorer

This 2008 Explorer had been in who knows how many times for oil changes. The instructor who drives it makes a 120-mile round trip to work and back, and once a couple of years ago she came in with a bad engine vibration due to a busted cooling fan and two full-grown dead cats lying in the bottom of the fan shroud.  On another trip, the pulley ring of her harmonic balancer had slipped back toward the engine so that the belt was riding on the naked rubber part of the balancer, and the crank sensor was being machined away by the misplaced pulley. We saw two of those slipped 4.0L balancer failures that same week and haven’t seen another one since.

	This 2008 Explorer had been the equivalent of 10 trips around the world before the spark plugs were finally replaced, but it still ran like a champ.

On a humorous note, we decided on one trip to check the fuel filter on the Explorer, which was almost completely blocked. I used that for an object lesson as to why it’s always a good idea to check the fuel filter on a high-mileage vehicle. There was a time when Ford required the filter replaced every 15K on trucks. Later when I was changing the oil on my 2007 Taurus I decided to check the fuel filter and it was just as bad as hers was.

On the last oil change, I suggested we have a look at her spark plugs and it turned out that they were the originals – with 238,000 accumulated miles, and this one was still running great with not so much as a flicker from the MIL. The plugs had the paint spot on the tip and on the way out they did that heavy-duty squeaking ancient spark plugs do when they’ve been in there forever. Furthermore, the business end of those plugs was textbook worthy.

The Suburban

About the time we got the transmission out of the Avalanche, a high-mileage 2004 Chevy Suburban came rolling in with an engine skip that turned out to be on cylinder 4. This one was blessed with the trusty old 5.3L, which I like because of the camshaft-in-the block, but even without the overhead cams and all those nylon sliders and tensioners, this engine isn’t without its problems. Camshaft lobes wear down and head gaskets blow. When we pulled the plug out of the misfiring cylinder, there was a piece of ceramic that had been cracked and shucked off the center electrode sheath by some catastrophic mechanical event (that according to the Denso chart anyway), and that cylinder had no compression. A cylinder leakage test fingered the exhaust valve, and I wondered if that chipped-off piece of ceramic might be stuck in some valve carbon holding the valve open, but it would seem to have been hammered to bits and spit out the back, because that’s what usually happens.

We won’t know until later this summer what happened on the 2004 Suburban to cause this, but the cylinder it came from has almost no compression at all, and since the mileage is so high we’ll probably stuff an engine in it.

The prevailing question I had was what had caused the spark plug’s ceramic to fail in the first place. Were there detonation or preignition events that cracked and damaged it or what? They had to go on a trip and opted to drive it that way, but in the coming month we’ll stuff an engine in that one – the cool thing is that we can upgrade to a 6.0L if we want to because the 4.8L, 5.3L, and 6.0L are plug-and-play engines.

The ’98 F-150

One of my colleagues owns an F-150 he inherited from a relative, and we got one of those laundry list requests – the fuel economy had dropped off, the passenger side power window wouldn’t work, the transmission needed servicing, the intermittent wipers were intermittent, and, of all things, the Check Engine light didn’t work – and he wanted all of it fixed. A lot of people “fix” the MIL by covering it with a picture of somebody or by installing a piece of tape blocking the view of it, but this one had a breach in the wire between pin 2 on the PCM and pin 13 on the bulkhead connector, so we did an overlay on that one and brought the MIL back to life. Several of my people worked on that problem because it was a great troubleshooting and repair exercise in electrical systems, and it was a bug I didn’t plant.

This ’98 F150 had a laundry list of issues, the least likely of which was the inoperative check engine light.  We ran an overlay between the PCM connector and this bulkhead connector and got the light back online.

For a truck this old, that re-operational MIL might be problematic, because now, if the truck had issues of which he had previously been oblivious, he’d be swinging by regularly to have those issues handled. After we replaced the spark plugs, the passenger-side window regulator, the PRNDL indicator and the Combination Switch, the truck had no starter operation, and we tracked that to the big C172 connector near the battery – one of the students had begun disconnecting that connector, gotten side tracked, and left it that way. In the end, that F-150 rolled out with no codes and no illuminated MIL, which was something of a surprise on such a high miler.

The hunting truck and a Nissan

The Toyota pickup on which we had used head gasket sealer came back in for a timing belt and a water pump – it still wasn’t leaking coolant any more, not even from the water pump, but the bearings in the pump were rattling, and so we stripped it down and did the kit thing – belt, idler, tensioner, water pump, etc. After we filled it with coolant and fired it up to do the final burp-out, I saw coolant leaking from the rear of the engine and discovered a head gasket breach that was trickling coolant down the bell housing. Whether he’ll want to redo the head gasket sealer or replace the head gasket remains out with the jury, but he opted to take the truck and use it for a while, keeping a check on the coolant level. His prerogative, I suppose.

The Toyota hunting truck revealed this leak after we did a water pump and a timing belt.  It was a tough shot to get, but in the real world you can see coolant trickling from under the right cylinder head. This stain told the tale.

Then there was the 2000 Nissan Frontier with an A/C belt squeak after a few minutes of at-idle A/C operation. This was condenser airflow-related because the head pressure started out normal and slowly climbed until the compressor had to struggle. Checking for radiator and condenser fin blockage, we rinsed them out with soap for good measure but to no avail. When we put a fan in front of the condenser blowing through it, the pressures normalized, and when we tested the fan clutch by heating the bimetal spring, it never got any stiffer, so we fixed that one with a fan clutch.

Finishing up the Avalanche

The power steering leak on the Avalanche was the last thing we tackled on that one. It wasn’t leaking from the pressure hose as we had figured. It was dripping fluid from the hydroboost unit, and so it’d need one of those babies to close out that job. We got one from the parts store, swapped it out, refilled everything, used the vacuum bleed cap I built to purge the air, I charged out the parts, and we put that one on the yard. Oh, yeah, we polished the headlights on that one too, and the whole truck looked better. “It’s the little things,” as one customer told us. We do what we can to breathe new life into those high milers, and it felt good to be done with another one.

Article Details

Tue, 08/01/2017 (All day)

Richard McCuistian

<p>The ones that just keep on givin&rsquo; sometimes need help.</p>

<p>high-mileage, vehicles, leaks</p>

The catalytic converter was introduced nearly 50 years ago because of EPA-ordered cuts in emissions, and in response to those orders, auto industry execs said the EPA’s targets could never be met. But thanks to old-fashioned American ingenuity, they were. What the EPA conceives, our engineers always achieve. Fuel-cell engineer Jonathan Frost once said: "When the U.S. introduced clean air legislation in the 1970s, many engineers said that cleaning up emissions from cars was impossible, but the legislation was passed anyway and new technology was invented in the form of the catalytic converter."

In 1972, Ford President Lee Iacocca said that “if the EPA does not suspend the catalytic converter rule, it will cause Ford to shut down.” He was obviously wrong, but at the time, the prevailing wisdom was that the catalytic converter was a near-impossible concept, overly expensive and inefficient, pegged as an idea that would never, ever work.

These honeycombs are tough enough to do the very precise job required of them, but fragile enough to be rendered ineffective if things go wrong and stay wrong for a while.

The 1970 mandate that auto manufacturers would be required to reduce harmful emissions by 90 percent by the 1975 model year drove Engelhard Industries and Corning Glass to propose the device that would later become the catalytic converter. A “catalyst” foists chemical changes on other elements while resisting any change in itself. The catalytic converter adds the necessary oxygen molecules to CO and HC (the exhaust from rich mixtures), to change those harmful elements into CO₂, which is the same thing we breathe out. The exhaust gases flow from the combustion chambers through the catalytic converter’s core, which is a block of ceramic material honeycombed with tiny lengthwise channels, designed to force every cubic millimeter of the gasses into contact with the catalyst material, and that’s where the necessary changes take place.

Lab work finally proved that a catalytic converter would work, but mass-producing them became a new and even more difficult hurdle. Engineers would have to take an abrasive clay mixture and force it through a shaped die at high speed to create the complexities of structure we see in cat-cons today. This process is called “extrusion” and at the time it was very commonly used for creating things like metal pipes and hollow noodles, but nothing anywhere near this complex had ever been attempted. It was a daunting task.

But that wasn’t all. Once that soft block of honeycombed clay emerged from the die, it first had to be cut to the proper length and then heated simultaneously inside and out until it was totally firm. And all this had to be done without distorting those tiny channels or causing the clay to crack, and then they had to find a way to coat all the channels with a layer of very fine platinum particles so that the platinum wouldn’t simply fall off after repeated (and vast) temperature swings. Under normal conditions, a catalytic converter races from ambient temperature to 800° F in 30 seconds, and the temperature of the gases can climb as high as 2,000 degrees. The catalysts on the vehicles I’ve datastreamed lately will normally float between 1000 and 1700°F while driving. In early development, on nearly every prototype, thermal expansion ruined the guts of the converter after just a few drive cycles.

The contrast between a pair of good catalysts (top) and a bad one is easy to spot using the PIDs.  If the rear O2s mirror the front ones this completely (bottom) the cats are no longer cats.

But then it was discovered that samples of clay from one mine in Georgia showed much better heat resistance. This clay turned out to consist of microscopic needle-like units aligned in such a way as to withstand the thermal expansion, and that was the key to making a cat that would last. The cats were off and running, and it has since become our job as technicians to herd them.

Front and rear

Nowadays we’re accustomed to seeing the “light off” cat(s) mounted very near the exhaust manifold(s) to take advantage of the natural heat still present as the exhaust has just made its exit from the combustion event – this front cat is the one sandwiched between the front and rear O₂ sensors, and the oxygen that is stored in this converter is extracted from the NO_X that is created during the combustion process, leaving N₂, which, to quote Bernie Thompson, is the cylinder’s “working fluid” — combustion heats the nitrogen so that it expands against the head of the piston, pushing it down and spinning the crank around. The oxygen extracted from NO_X in the front cat is used in the rear cat to handle CO and HC, converting them to harmless CO₂, oxygen, and water vapor, which is also created during combustion.

The aft-cat O₂ sensor monitors oxygen storage and that sensor’s signal should switch much more sluggishly than the front O₂, but if the rear O₂ begins to register a problem, the PCM will do what it must with the fuel trim to keep the rear O₂ (and the cat) happy, so be ready for that in case you ever see it happening.

This display shows healthy cat activity, but also healthy cat temperatures (Celsius). I have set the Android radio I have in my 2006 Explorer to display these parameters during normal driving. The diagram shows which gasses are handled by the converters. The front one is the “light off” cat.

So, what damages the cat? Well, engine misfires (caused by no spark or low compression) can lead to overheating and potential meltdown of the substrate. It can be contaminated by silicone sealants (or liquid spray), coolant leaks into the combustion chamber that coat the strata, excessive oil steam blow by that is picked up and processed by the PCV system and sent out the exhaust, high sulfur fuel, and rich fuel mixtures forming carbon deposits. Any of these elements (and some others, like leaded fuel) can quickly coat the catalytic substrate, effectively preventing it from working effectively. Catalysts sometimes just wear out. The brick may break loose inside the shell and dance around in there or chunks may break off the engine side of the cat and rattle around, preventing good exhaust flow. Overheating can also cause cats to break up into dusty, abrasive particles that find their way through the EGR system and into the combustion chamber, a scenario that is an engine killer of the first magnitude. And there are times I’ve seen the vermiculite blanket around the outside of the brick shed material that will clog enough of the passages that exhaust backpressure rises and the engine begins to lose power because it can’t breathe.

The codes and the protective PCM

Just about everybody has seen the P0420 and 430 codes flagged because the rear O₂ is reflecting poor oxygen storage, but that doesn’t always mean the cat is bad. The honeycomb will sometimes be coated with one element or another that might well be burned off when the rest of the system is repaired to work right. With that in mind, other DTCs should be carefully considered before condemnation of the cat. Hydrocarbon soot initially cools the cat and makes the O₂ sensors sluggish, (skewing the mixture even more) and the soot coating prevents the precious metal substrate from doing its job.

Problems maintaining fuel control can prevent a catalytic converter from working at all. The cat needs a very precise mix of feed gasses to “light off,” and the range expressed in Lambda is very narrow indeed — 1.005-0.995.

Whenever you see other codes displayed that can have an effect on the efficiency of the cat(s), go after those codes first, then complete a couple of drive cycles to see if the cats will clean up their act and start working right.

One of the first times I encountered PCM cat protection was in the late ’90s when I was working on a Windstar that had all the EGR ports clogged except number four. When EGR was flowing, that one cylinder was getting it all, which created a somewhat mysterious misfire in warm off-idle mode. When I started working on that one, I noticed that when I cracked the throttle, it would begin a very steady misfire on four, and as I was doing my troubleshooting, I noticed that when the misfire was under way, the number four injector would stop clicking, which led me to believe there was a problem in that area. Not knowing that the PCM strategy was shutting the injector down to protect the cat, I did some circuit tracing before I realized that disabling the EGR did away with the skipping, and that’s when I found the reason for the misfire. Ford’s instructors had, at that point, never told me about that strategy in training, but maybe I missed it while I was grabbing a cup of coffee.

If the rear sensor picks up on a consistently dreadful imbalance at the cat’s exit stream and reports it to the PCM, the box might realize that the front O₂ is unreliable and fuel trim strategy might be modified based on the rear O₂ feedback to protect the cat. This will vary from platform to platform, but the PCM’s concern about the cat’s health is very real.

Once again, all other codes related to air/fuel should be addressed first. MAF, IAT, ECT, rich/lean codes and fuel trim issues would be the focus, along with a careful consideration of the EVAP system and even the condition of the engine oil, both of which can be the source of excessive HC.

After dealing with the other pertinent codes, make sure you’ve recorded them, erase them, and then start the engine. Hold it at about 2500 to light off the cat, all the while watching front and rear O₂ sensors. With a front O₂ switching rapidly and a rear O₂ trace a lot less active, the converter should be OK. But if the rear O₂ sensor is mimicking the front one on a system that is otherwise healthy, the converter is probably ready for the scrap pile, but it’d be wise to dump the codes and complete a drive cycle to see if the converter monitor will flag a problem with the cat before you make your final decision. And there are other considerations.

If the only code is a cat efficiency code, check out the freeze-frame data. If the fuel trim was high when the code was set, it might indicate unmetered air, unreliable MAF readings, or a skewed BARO reading from a speed-density MAP sensor; the fuel pulse will be wrong, and that’ll create a genuine lean condition. The PCM will respond to the O₂ sensor(s) lean reporting by dumping extra fuel into the intake to bring things back into balance. If this is happening on just one bank, it’s not likely to be MAF or MAP related and more likely to be something only affecting that bank.

Whenever these shenanigans have taken place (for whatever reason), there’ll be MIL lights and contraband, poisonous gasses galore.  The 2003 Wrangler got a $400 bolt on replacement set.  It had been purchased used by a doctor who wanted this “mod” reversed.

If the fuel trim is double-digit negative, it typically indicates extra unmetered fuel is finding its way into the chambers and the ECM is compensating by subtracting pulse time. This can be fuel injector pressure regulator related, either because the regulator diaphragm is leaking or because it isn’t regulating the pressure at all – shoving 100+ psi of fuel through the nozzles. I’ve seen that more than a few times. And cam timing errors can cause fuel trim anomalies too, so watch out for that.

Visuals and audibles

A cat that is dented or rattling is obviously in need of replacement, because the brick usually can’t take that kind of thing without suffering damage. A discolored converter (“blued and hued,” like some gun parts) is also suspect, because it must get blistering hot to change color that way. It’s also a good idea to get eyes on the front of the brick with a borescope or whatever method you can – if it has clogged combs, is breaking up, or is obviously contaminated, it’ll need replacing, but first you need to find the source of any contamination. You need to find the cause before you attack the effect. Temperature and backpressure tests are a good idea too – it should be hotter at the outlet than at the inlet, and you shouldn’t have more than about a pound of pressure in front of the cat – a good one won’t even have that much. Keep in mind that the temperature test only tells you whether or not the conditions are right for the cat to light. It, alone, does not mean the cat is no good.

Another common cause of P0420/0430 DTCs are leaky exhaust systems. Even pinhole leaks can suck enough oxygen in to cause a problem. Use your smoke machine to locate the presence of leaks, especially any upstream from the cat and within a foot or two of the backside of the cat.

Then there are those converters that look just fine on the outside but have been gutted by somebody for one reason or another. Back in the 1980s when I was working at a large Ford dealer, some of the mechanics would buy a brand-new truck and immediately have the exhaust system totally re-done – doing away with the cats in the process. For the life of me I’ve never been able to understand why somebody would do that to a new vehicle.

Finally, the only really reliable test to find a partially clogged cat (my opinion) is the backpressure test taken at the O2 sensor port.  The cat pictured here had only 5 psi of backpressure and the customer’s complaint was low power, harsh transmission shifts, and poor fuel economy. Less than 2 psi backpressure is optimum.

The overarching point is that not every catalyst efficiency code necessarily condemns the cat, although there are many times when that is the case, particularly if everything else is as it should be.

If you’re replacing the cat with anything other than an OEM, make sure you get one that meets the application, and not a “universal” – not all cats are created equal. Back in the 1990s we diagnosed a dead one at the dealer and let the customer talk us into having a replacement put on at a local muffler shop. The replacement converter threw efficiency codes on the first drive cycle. Today, even using one that “looks” right may lead to repeat codes.

Article Details

Thu, 09/28/2017 (All day)

Richard McCuistian

<p>So, what damages the cat? Well, engine misfires can lead to overheating and potential meltdown of the substrate. It can be contaminated by silicone sealants (or liquid spray), coolant leaks into the combustion chamber that coat the strata, excessive oil steam blow, and more</p>

<p>catalytic converter, PCM, auto repair</p>

One day I got a very terse call from the vice president of the company where I was responsible for fleet maintenance back in the late ‘70s. It seemed that an almost new (1978) Dodge one-ton we had was pointed at the gate with a gooseneck trailer behind it and that truck and trailer needed to arrive at our offshore diving and salvaging dock within the next 30 minutes – 25 miles away. I had no idea why that trip to that dock was so urgent, but someone had misplaced the key to the Dodge.

“Get that truck started and on the road within the next 10 minutes,” he told me with his gravelly voice, “and I don’t care what it takes. Just make it happen.” 

I must admit that I was in my element under pressure in those days, so I hung up the phone and grabbed a jumper wire with a couple of ‘gator clips on each end out of my toolbox. I opened the hood on the Dodge and made a connection from the positive battery terminal to the ballast resistor to feed current to the ignition coil. Making sure the tranny was in neutral, I “pocket screwdrivered” the starter to fire the engine up. Ninety seconds had expired and the steering wheel was still locked, but I knew I could defeat the pewter collar around that silly spring-loaded steering wheel lock peg, and I slid into the seat and muscled the wheel hard to the right, and broke the lock. Mission accomplished in less than three minutes and the truck was headed out the gate.

Then there was the time at that same job where I had to drive down Highway 87 toward Galveston and take a steamy ride on one marsh buggy through a swarm of mosquitoes and dragonflies to another marsh buggy that had jumped time, stranding a different vice president and his passengers a couple of miles off the road. Putting a timing belt on while standing in snake and alligator-infested water and swatting away mosquitoes wasn’t my idea of a good time, but I was motivated enough that I got that job done in record time, too.

This is my 2007 F150 that was victim of a surgical strike by some toothy critter that was copper-hungry

The point is that every job isn’t interesting, but in our line of work, challenges are the spice of life, and it feels good to be a problem-solver. It feels even better to be appreciated, and usually we are, but that isn’t always the case.

Critters

Dogs and squirrels chew wires, as do rats. Rats and squirrels build nests in engine compartments, and cats looking for a warm place to sleep can die under the hood and under the car in very gruesome ways sometimes. I’ve had to kill spiders and roaches, wasps, dirt daubers and all manner of other wildlife in my under-the-hood and under-the-vehicle odysseys. One morning I did a classroom presentation on critter damage, and a day or so later I walked out to where I park my own F-150, slid in behind the wheel, and thought I was going somewhere in my truck, but it wasn’t to be. The battery was good and hot, but I had no starter operation and no scan tool communication. The red theft light was blinking, which can point to a few different problems, but it usually means a module (usually the PCM) isn’t talking. With the key on, I checked for voltage at the EGR assembly and found 9 volts on the gray-red signal return wire – which should have been grounded through the PCM. What that meant to me was that the PCM had lost its own ground reference somehow.

Having Alldata available on the smartphone is pretty handy when you’re under the gun to find out what’s wrong and you’re somewhere else besides the shop

Next it was time to bust out my smart phone and dig into ALLDATA, where I found that PCM G103 is located behind the battery on the bulkhead. With my flashlight, I peered down there and saw that about eight inches of that wire had been removed by some sharp little teeth and my much larger main power feed cable to the inside fuse panel had been just as viciously attacked, but it had survived without being severed. Some chew-happy squirrel must have a nice piece of wire lining its nest and a belly full of copper as I type these words.

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There was another ground wire in that same area that was compromised as well. While removing the battery and doing some solder and heat shrink work was almost enjoyable that Saturday morning, I found myself wondering if I was going to have this problem again. No other wires under the hood had been attacked.  It was almost like the critter had pulled up a wiring schematic and did a surgical strike to prevent my truck from going anywhere. And it worked.

I suppose I should have been thankful that these wires were the only ones the critter chewed – he could have done a lot more damage than he did – fixing this took about thirty minutes.

I prevailed in that fix and placed some rat poison in the general area. We’ll see how that works out.

The 2004 Suburban

In a previous article, I mentioned a 2004 Suburban with a 5.3L that was misfiring on cylinder 4 with low compression and, during the cylinder leakage test air was escaping into the exhaust, but the owner chose to drive it skipping for a while before having it fixed. Finally, the Suburban returned and we hashed out what needed doing.

This was one of those high-milers, and so I talked them into a reman engine because of the better warranty, which we managed to stuff in there in pretty good time. 

We were going back into the Suburban with the reman engine and had just put it in place when this photo was taken. You can see the burned valve in this photo of the old engine’s head if you know what to look for.

After the swap, I had Robbie jerk the head off so we could inspect the valves and the head of the piston on the offending cylinder and we found a valve that had become mis-matched with its seat and was leaking compression. With the new engine in place, the MIL was off, the monitors all cleared, O2 sensors were switching handily, and fuel trims were bouncing around the zero line, so we put that one back on the road. There was a strange caveat though. For some reason, the transmission wouldn’t go into park well enough to not roll away on a slope.

This was a deal-breaker, to be sure. The shift cable was adjusted as far as it could go. I could disconnect the cable and put the transmission fully in park, so there was nothing wrong inside the case. Eventually I decided to try the shift lever off another transmission I had on the shelf and with that lever installed, it would go completely into park just fine even though it looked the same. I have yet to figure that one out, but it was safe when it left.

The Silverado, the Fusion, and the MKZ

While all this was going on, another instructor who drives a 2003 Silverado 2500 Duramax asked if we could replace his master cylinder. He’s ordinarily pretty savvy, and since he brought us the master cylinder I had a guy pop it on there and begin the bleeding process. Well, the pedal felt like you were stepping on a plum, and there was fluid dripping from underneath the truck and we found that classic rusty brake line situation a lot of you guys have to fix every day. He didn’t look under the truck, I don’t guess. A careful exam of the whole system revealed that this line was a lot worse than any of the other lines, all of which looked pretty good, and so we got a roll of that dandy nickel-alloy rust-free stuff and built a replacement line from stem to stern (complete with new double flare fittings), and after the bleeding procedure, we got that one rolling again with a good firm pedal and a master cylinder he didn’t need. I gave him the rest of that $60 roll of brake line just in case something else would be needed later.

This rusty brake line syndrome is fairly common everywhere on trucks of all kinds, especially on trucks that do a lot of mudding, but salt did this one in. This Silverado had spent its early life in Panama City Florida, where the salt air took its toll.

The 2010 Fusion that came in around this time was making a bump noise underneath on the left side during parking lot maneuvers, and it was one of those cranky situations where you can’t see anything but you know something is wrong. And every bolt was tightened to no avail. This one has that odd double-ball joint design with two lower control arms, and when we applied the Chassis Ear^® we found that one of the control arms was the source of the bump, and when we got it out of there you could see the problem. The hidden rubber that is couched in the frame area had died, and that was allowing the sudden pressure of certain braking and steering maneuvers to give a metal-to-metal contact sound. The fix was easy enough.

This inner control arm bushing isn’t visible on the Fusion until you remove the control arm. This was the rear of two control arms that car is blessed with on each side.

That Fusion reminded me of another vehicle, a 2012 MKZ that came in with an alternator you could hear whining from 100 feet away. She had been to a tire shop complaining about a noise, and the first guy who rode with her at that shop said he thought the noise was a hub bearing, but the more experienced mechanic said, “no, that’s the alternator,” because it was making the noise when the car was sitting still and the pitch of it matched engine speed. When I heard it, I agreed with the older guy’s prognosis. That alternator was making a LOT of noise that changed with throttle.

Getting the alternator off a 2012 MKZ isn’t for wimps — the refrigerant has to be recovered and the A/C compressor has to be removed, and the alternator comes out the bottom. There’s nothing easy about any of that job, but my guy got it done. I knew this 17-year-old could handle it — he had just finished replacing the heater core in a 2010 Wrangler, and after that extremely difficult job, this one was a cake walk.

The new alternator didn’t whine — the car sounded normal under the hood now, but it did have what sounded like a noisy hub bearing on the right front at road speed. It was one of those situations where the customer didn’t believe she had needed the alternator to begin with, because she was still hearing a noise on the road and one noise was masking the other. She chose to drive the car for a few days but came back and claimed the car had “put her down” and implied that it was our fault for replacing the alternator.

Here was another needful repair. The customer on this one was complaining of a vibration with the blower on high – easy to figure out and easy to fix, but needful all the same.

“I left it running when I got here,” she told me, and then said, “I had to jump it off this morning and then I drove it here (15 miles). It wasn’t giving that problem before you replaced my alternator.”

I had her pull it into the shop. I carefully explained that if the alternator wasn’t charging, the engine would have died as soon as the jumper cables were removed. Then I switched the car off and tried to restart it, but the battery was too weak. When I jumped it off and connected the Snap-on tester I showed her that the alternator was indeed charging and suggested that she find a cool place to rest while I did some more troubleshooting to figure out what was going on, but I told her I’d need the rest of the morning to be sure of what was going on.

“There was nothing wrong with my battery,” she snipped. “We’ll get to the bottom of this,” I told her.

After she walked away, I put a good stiff charge on the battery with a heavy-duty charger, then I got out the $1,700 Midtronics unit I bought from Joey Henrichs and ran through the entire routine, which records everything, including battery health and alternator ripple, printing it out for the customer. The MKZ showed a clean bill of health all the way around except for the battery.

Taking it a step further, I did a parasitic drain test, connecting a meter in series with the battery and waiting until all the modules finished charging their stuff. End of story — there was no drain, only a weak battery.

When she came back I showed her the results and told her she’d need to get the hub bearing noise handled at the tire shop. Sometimes it’s best to send some customers down the road, so that’s what I did.

Another Silverado

This 2003 1500 5.3L came to us with an overheating complaint — the guy said another shop claimed it must be a blown head gasket, but I explained that we wanted to diagnose it ourselves before we did any unnecessary surgery. Sure enough, it was overheating, but it was happening slowly, and there was no quick pressure buildup in the cooling system when the engine was started. The fan kicked on at 228 but the engine kept getting hotter until the fans kicked on high, and all that took a while, but I noticed that the radiator was still cool.

Here’s the overheating Silverado. Even with the radiator removed and bypassed and the thermostat gutted there was no flow through the hose.  Presumably this was a water pump problem?

“Let’s try a thermostat,” I told my guy. Cheap and easy comes first. We put one of those in there and burped it out, but nothing changed. The radiator was cool, but the engine was getting hot.  So I had him pull the water pump, and the borescope didn’t show anything wrong down in the pump, so we reinstalled it. With the radiator removed (no external clogging seen) I bypassed the radiator using the long hose, and we also looped out the transmission cooler lines and took the guts out of the old thermostat to allow free flow. With the engine running we had to squeeze the hose in the middle to neutralize the natural kink so as to facilitate flow but even with that hose in place of the radiator, there was still no flow through the hose, which was only warm on the ends — not in the middle. And the engine continued to try and run hot. What madness was this? If coolant had been flowing, the hose would have been hot its entire length.

Here’s the Silverado’s water pump with the rear cover removed, but I couldn’t see a problem, nor could I feel one manipulating the pulley and holding the impeller.

This was one of those exhaust bolts that had rust-melted from a 15mm down to something just a little larger than a 9/16, and it wasn’t in an easy place to access. We air-hammered this wiggler onto the bolt to get it out. It was a needful thing, but getting the bolt separated from the socket was tough.

To make a long story short, a radiator and a water pump fixed that one. Mission accomplished, but I couldn’t figure out what was at the root of this problem — I thought that plastic impeller might have been spinning on the shaft, but water pump forensics didn’t show that to be the case. One way or another, the truck never runs over 210 degrees now. Happy customer.

Article Details

Fri, 12/01/2017 (All day)

Richard McCuistian

<p>Every job isn&rsquo;t interesting, but in our line of work, challenges are the spice of life, and it feels good to be a problem-solver. It feels even better to be appreciated, and usually we are, but that isn&rsquo;t always the case.</p>

<p>auto repair, Silverado, Suburban</p>