Trade secrets

Motor, Mar 1998 by Cerullo, Bob

Letting the day-to-day problems of running a repair shop get to you can only beget more problems, not to mention a lot of sleepless nights.

There are 26 oblong slots in the base of my bedroom ceiling fan. Each of the five blades is held on by three screws. The rattan decoration on each blade has 60 round cutouts. I can provide these useless statistics with great certainty because I recently spent yet another sleepless night worrying about problem jobs in the shop.

Counting sheep doesn't do it for me, so I stare up at the ceiling fan over our bed, hoping that somewhere in the gloom a solution will appear. I know I'd be better off getting a good night's sleep and facing the next morning's problems with a clear, well-rested mind. But the reality is that I have trouble sleeping when I leave a problem at the shop overnight.

That particular night I actually had two problems to wrestle with. The first was kind of a combination of problems, with the job and with the irritating car owner. The owner was one of those fast-talking wheeler-dealer types who likes to talk incessantly and simply doesn't listen to anything you say. I'll call him "Moe Mouth."

Moe brought in his 1986 Olds 98 with the 3.8liter engine, complaining of intermittent stalling. During a road test I took with Moe, the car did not stall, nor did the Check Engine light come on. Back at the shop, after Moe had left, we ran the car through a basic computerized engine analysis and a check of trouble codes. Fuel pressure was good and the engine was actually running pretty well. By the time we had finished all our testing, about two hours had elapsed.

Then Moe called, wanting to know if the car was ready. I explained that none of the symptoms he described had occurred, but that we were going to keep trying. Moe found it unbelievable that our analyzer didn't find anything wrong. I explained the difficulties of diagnosing intermittent die-outs, but it seemed Moe let my words go in one ear and out the other.

Elsewhere in the shop, we were trying to figure out a noise emanating from the right side of a front-drive Chrysler 3.3-liter V6. The customer, a fellow I'll call "Joe Great," was planning to take a long trip by the end of the week and was eager to have the noise silenced. The noise on the transversely mounted engine sounded somewhat like a worn timing chain, although it made a different kind of sound, as well.

Before committing to an estimate, I wanted to get the belts off and make sure the noise wasn't related to a belt-driven component like the water pump, alc compressor or power steering pump. We started by trying to remove the belts. In the process, we found that the belt tensioner was seized and not maintaining tension. In fact, to remove it, we had to unbolt some brackets because the tensioner could not be released in the normal way.

When I called Joe to explain the problem, he listened carefully, then repeated what he understood, which was that the belt tensioner would have to be replaced regardless of whether we were to later find a worn timing chain. Joe agreed to have the work done, and we proceeded.

With the belts off, it took just a couple of minutes for a ruckus to start in the area of the timing cover. Joe agreed over the phone to the estimated price of a chain replacement, and I noted the time and date on our work order. In New York State, repair shop license regulations require that every verbal authorization be noted on the final invoice that's given to the customer at the end of the job. I'm not sure what that proves, but that's another story.

I assigned an experienced mechanic to replace the timing chain, provided we found it stretched when we finally got to examine it. In the meantime, I reached for one of several well-worn books of valve timing mark diagrams that we use whenever we're replacing a timing belt or chain.

After a while, I got back to the mechanic who was working on Moe Mouth's car. Finally, after several tries, we experienced the intermittent stalling Moe was talking about. After warmup, the engine would roughen up and die. It would restart immediately and fuel pressure remained rock solid throughout the die-out. It was as if someone had just shut off the ignition key. We checked the wiring circuits between the computer and the module, physically checked the crank sensor and, at one point, actually installed a spare crank sensor we had lying around. Still, the engine died after warmup. Next, we hooked up our lab scope to check the voltage to and from both the crank sensor and the camshaft sensor. No problems there. Everything in our tests kept pointing to a defective ignition module.

Past experience with this DIS system, however, has taught us that it's tough to rule out the computer as the source of a sudden die-out. In the process of checking that out, we discovered that the PROM was two generations old.

I called Moe and explained that we believed a new ignition module would solve the problem, but at the same time strongly suggested that the PROM be updated. I tried to explain the possibility of a defective computer, but my explanations were not penetrating Joe's wall of calculated ignorance. Also, he didn't seem to understand that the price of a new modulenearly $200-didn't have anything to do with the fact that the car was an '86. His argument was that it was an old car and shouldn't cost that much to fix.