A tech's life

Jan. 1, 2020
Then there are those jobs we tend to remember, to talk about over a cold beverage at the end of the day. Here are a few of mine I’d like to share

For the most part, days in the shop are routine. Customers come in for oil changes, safety or emissions inspections, tires, brake work and a host of other routine repairs that most of us can do running on only 50 percent brainpower.

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Then there are those jobs we tend to remember, to talk about over a cold beverage at the end of the day. The jobs that took us into a new arena, or really stressed our abilities to the limit, forcing us to grow in the process. The jobs that we successfully completed when others said no and walked away and the ones that made us feel like idiots once we learned the answer. Here are a few of mine I’d like to share.

Oil Leaks
The car was a 2001 Mercedes Bens SL500 and the repair order read, “Check for oil leak.” I brought the car in and proceeded to look over the engine compartment from above and below. Truthfully, I’ve never seen a cleaner engine compartment. No leak of any kind was visible.

OK, let’s move on to other sections of the car while its up in the air. Maybe the customer is seeing transmission fluid on her driveway, or some other fluid leak. I checked from front to back with no luck.

“Tom,” I said to my young service writer, “I can’t find any leak
anywhere. Can you give me a clue as to what I’m looking for?”

He walked with me to my service stall, and pointed out a fluid drop on, of all places, the front passenger seat! OK, you could have been more specific on the repair order.

This model is a convertible, and I haven't had much experience with Mercedes in general, and with this model in particular. I looked more closely at the passenger side visor and noticed a wet stain just above it, along the trim for the upper edge of the windshield. A quick swipe proved that it was, indeed, oil and not water leaking in.

I know convertibles use either hydraulic actuators or electric motors to operate their tops, but so far every top I’ve done used manual locking devices up front and nothing more. Some reading up, though, on the SL revealed that there were actually two hydraulic units above the glass, used to secure the roof locks. The passenger side’s piston seal had failed and every time the top was opened a small amount of fluid would be lost.

Replacing the actuator was a straightforward repair. Repairing my service writer, however, may take a bit more work!

Critters of all Kinds Every tech has a critter story. Rodents of all kinds love to nest in the strangest places, and for some reason they often find electrical wiring a tasty snack. Then there are those critters that make your skin crawl
when you are sitting in the car and one flitters across your leg. The critters in this story are a unique little bug called the German cockroach.

I’ve been in cars infested with these only a few times, and when the infestation is bad, the odor is unmistakable. Down South, these creatures are often introduced into a new environment from grocery containers that contain one or two. All it takes is one pregnant female to begin a new batch.

They are prolific breeders and love to nest in the tightest of cracks. There are literally thousands of places for these little creatures to hide, and my customer wasn’t happy about driving along, minding their own business, and having one of them decide to crawl across their leg. Some folks have such a phobia when it comes to bugs, that this could even be classified as a “safety” issue. The droppings they leave behind can also cause health issues for many people, so when this customer came to us for help it was hard to turn down.

Like any living thing, the German roach needs food, water and shelter. The car was a Mercury Mountaineer outfitted with rear AC,
and both evaporator cores provide plenty of water. Kids drop food all the time, and even one little bit of cookie is a feast for these things. Shelter? Forget about it! Any little crevice will do.

A common approach is to “fume” the car with a gaseous pesticide. This works for many insect issues, but the German roach is a tough little critter. It will kill many, but not all of these guys. There are always a few immune to the chemical, and their offspring will also be immune. In addition, there are too many places in the car the gas will not reach — places the roaches, however, can reach easily.

The cure I used was to completely gut the interior. The dash was removed, carpeting pulled out and cleaned, and all the door panels
pulled so the gas from the fumigation could get into everything possible. The Mercury sat sealed overnight to give the gas a chance to work. Then the car was opened up and allowed to air out, removing any residuals left.

To make sure all the stragglers were taken care of, a special bait was applied throughout the car; along the wiring harness tracks, both HVAC housings, and everywhere else the little buggers might travel looking for food and water. This bait does two things. It dehydrates the insect so no matter how much water he drinks, he’s still thirsty, and neuters the son of a guns so they can’t reproduce. While the results aren’t immediate, they are effective in eliminating the last of the survivors. This bait comes in a syringe applicator, and each placement need be only the size of a BB. Don’t use the “roach motel” baits. They aren’t effective for this pest.

The job was time consuming to say the least. But was the customer happy? You bet she was!

How Dumb Do I Feel?
This next story only demonstrates that I all too often had those moments when I was faced with a “non-problem.” Call it stories that make you go, “Duh!”

My youngest son owns a 1989 Jeep Comanche pick up, and together we’ve had more than a few diagnostic adventures with it. One of the earliest was a problem with the interior lighting. There are two lights on either side of the cab and neither was working when he first got
the truck. Hey, this should be an easy fix.

I popped one out of the trim in order to access the connector and checked for voltage to the assembly. The reading of 12.6 volts at least told me that open circuit voltage was present. Now on to the ground side of the circuit, where I noted a perfect 0.0 volt when I backprobed the connector. That could only mean one thing right? I had to have an open circuit between the two connector pins.

I switched my meter over to ohms and checked the resistance through the bulb. I had continuity there so the bulb is OK. Now to check for continuity between the positive and negative connections at the connector itself, with the lamp assembly disconnected and sitting on my workbench. No continuity.

Looking closely I noticed that one end of the bulb ran to a little U-shaped tang that acted almost like a detent for a metallic roller located on the end of the light’s lens. Something inside me said,
“Push!” and as I pressed on the lens, it rocked slightly to one side, bringing the little roller in contact with both the U-shaped tang and another metal strip that completed the path to the connector. Continuity restored, simply by “rocking” this rocker switch.

I reconnected the lamp assembly to the wiring harness and turned the key on. Dome light restored.

Duh.

Now for a “What The …?”
While I was still full-time in the bay, I had a customer bring in a Dodge Stratus with an unusual (for me) complaint. It’s Malfunction Indicator Lamp (MIL) was on, but there were no drivability complaints. The code was for the secondary air injection system, “low flow detected,” and I had never seen an air injection system on a Stratus.

The reason I hadn’t seen one was pretty simple. I live in Florida, and the car was a California model where the emissions standards are a little more stringent.

My diagnostic strategy isn’t important to the story, so I won’t bore you with those details. I narrowed down the problem to a restriction in the exhaust and prepared to remove the exhaust manifold to take a look. I was surprised that a car with so little mileage on it (the Stratus only had about 35,000 miles on the odometer) would have blocked passages, but that was all that it could be.

Or so I thought.

With the manifold removed, it didn’t take long to see that there was another explanation for the restriction. How about a cylinder head that
had no passages for the air injection airflow to follow? Somewhere, sometime, the cylinder head had been changed and replaced with a Federal head. The casting was there, but the ports weren’t drilled through. It may also have been possible that the entire engine had been swapped and the existing California parts bolted on.

What really got me about this job, and resulted in my mumbled “What the …?” was how the previous tech dealt with the situation. Knowing that he had a problem, he doubled up on the exhaust gaskets after cutting a slot in each, leading from the casting to the individual exhaust ports, effectively making ports of his own. This worked for a short time, probably long enough to get rid of the car and the customer, until they finally clogged and the MIL lit up the dash.

Wonder what else he rigged?

Learning to Look
I’ve had my fair share of missed calls. Let me clarify that. I’ve found problems that I was sure would cure the complaint, only to find out later that there was another issue hiding behind or near the first. And had I looked a little closer, or had paid a bit more attention; I would have found it too, instead of having to deal with a comeback.

I remember a Saab 9-5 customer was complaining of an erratic fuel gauge reading. No sweat; nine times out of 10 it’s the sending unit
and this vehicle was old enough to make that a likely suspect. But just to be sure, let’s pull it out and take a look. This pump is accessed under the rear passenger seat, and is pretty easy to remove. With the pump out, I hooked up my ohmmeter and moved the sending unit arm through its full range while watching the resistance change. Seeing some drop outs in the reading after doing this 3 or 4 times convinced me that the sending unit was faulty, so a replacement was ordered and installed. The car was returned to the customer.

And returned a week later. But you guessed that already, didn’t you?

Had I done something wrong? I had read the service information, and there was a specific note on how to install the pump to make sure the sending unit operated properly. I didn’t bother to question the information at the time, but now my curiosity was aroused. I removed the pump, and peered into the tank and could see that there was a depression designed for the base of the pump module and off to the side was an additional recess for the sending unit arm. If the pump were positioned improperly, the arm would stop high on the lip of the depression instead of being able to move to its lowest point of travel. But, I thought, that would make the gauge read partially full even when the tank was empty, and that didn’t jive with the complaint; erratic readings, that changed while driving.

Then I noticed something white and plastic floating in the fuel.

Apparently, this plastic was a baffle that should be fixed to the base of the tank. A call to our local dealer confirmed that this baffle sits in front of the fuel pump module, I guess to prevent normal “slosh” from getting to the pump. Now I'm thinking that this debris floating around in the tank was hitting the float arm and was the real cause of the complaint. Because the one I had was in pieces, a new tank had to be ordered.

Yeah, no doubt about it, interspersed among the routine tasks of the day are those that cause you to pause. Sometimes, its to smack yourself and ask how you could miss something so obvious and others, its to pat yourself on the back for a job well done. Isn’t that why we do the work we do?

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