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| Summer 2008 A dime-sized Rock by Rob Gaskell, Jr.As professional technicians, we take a tremendous amount of pride in the quality of work that leaves our shop. It’s a direct reflection on us, and one of the most heartbreaking things we face is a comeback due to a defective part. When this occurs, we of course want to get the vehicle back on the road as quickly as possible, since our customer is already less than pleased with the situation. This is particularly important in the field of fleet maintenance, where a single customer may represent a very large percentage of our total sales.
In addition to defective parts, we also sub out certain types of work, such as transmission rebuilds, to a shop that specializes in that field. Luckily for us, our transmission shop is second-to-none in our area, and we trust their work as we trust our own. On the other hand, we expect that if a problem should ever arise with a transmission they recently rebuilt, they will be equally as prompt and helpful.
Now I’d like to take you back in time, to the Fall of 2007. We had just gained a new customer, and if you read our article from the February 2007 issue of Brake & Front End Magazine, you are aware of how we were able to gain the confidence of this new customer. One of the first major repairs we performed for them included a transmission overhaul, on a 1996 Chevy C-3500HD with a 7.4L and a 4L80E transmission. As usual, we performed the removal and installation, which included a cooler line flush, bypass of the radiator’s internal transmission cooler, and installation of a new, larger-than-stock auxiliary cooler, as per transmission shop advice. The actual rebuild was performed by our friends at Oregon Transmission Center, and included a standard 12 month/12,000mi commercial-use warranty. Over the next 6 months, the truck returned several times for unrelated repairs, and regular preventive maintenance, at which time we inspected the transmission fluid condition and level, with no issues whatsoever. During a routine visit, minor repairs were performed, the vehicle was test driven thoroughly, and returned with no problems to report. About a month later, the truck was towed to our shop, with a complaint of an inoperative transmission, and a related underbody fire. I repeat, a FIRE. It seemed the transmission fluid had gotten so hot that it left the overflow tube on the transmission in flames, and its dark color and smell certainly indicated some very serious heat had occurred, not to mention the melted plastic from the completely destroyed internal harness and solenoids we later found in the bottom of the pan. We also noted that the engine was idling around 1800 RPM, which we initially speculated was probably due to heat-damaged wiring harnesses, or possibly damage to the PCM, but we were more concerned with getting the transmission repaired. During removal, I realized that the fluid had boiled out of the transmission with such force, it had melted away the rubber hose attached to the overflow tube, and hit the exhaust pipe where it burst into flames. Fortunately it was about 8 inches in front of the catalytic converter, which can be several hundred degrees hotter than the adjacent exhaust pipe, narrowly avoiding a potentially deadly result.
I called the manager at Oregon Transmission Center, and explained the situation. They were more than happy to honor the warranty, and by that afternoon, had the transmission disassembled. They called back, asking us to check the cooler and lines for obstruction, and explained that there didn’t appear to be anything wrong inside the transmission that led to the heat. They even contacted the manufacturer of the electronics inside the transmission, and asked if it were possible for a short to cause that kind of heat. Not enough electrical current, they were told, and no known cases existed. The clutches, although burned up by the fluid, showed no signs of slippage that could have caused the heat. The cooler and lines could not have been freer flowing, and the cooler was given to Oregon Transmission Center at their request, as we would not be reusing it. It seemed that this transmission had cooked itself literally to flames and not even the transmission experts could explain why. I reinstalled the transmission, disappointed with the lack of explanation and wondering if I would be doing this again in a few months. After adding fluid, I started the truck, and began to diagnose the fast idle. I noted that the engine would race to about 3,000 RPM on startup, and as the Idle Air Control motor closed completely, would drop to about 1800. Normally, closing this valve completely would cut off nearly all airflow into the engine and cause a stall. I suspected a vacuum leak, but also noted the fuel trim, a measure of how long the fuel injectors are pulsing compared with the expected length of time they should be required to pulse for a given set of data, was hovering between –2 and +2, which certainly did not indicated a vacuum leak, as a vaccum leak will cause high positive fuel trim numbers, but I decided to check for one anyway with a smoke machine, which uses low pressure smoke to check for leaks, since we feared PCM damage to begin with. As I expected, no apparent leaks were found. There were no codes, except transmission codes that would normally be present with a transmission failure, and the Throttle Position Sensor values appeared completely normal. It was obvious the Idle Air Control motor was in fact working, since it did reduce the idle considerably on startup. Against the indication of the TPS values, we suspected that the throttle body must be sticking open. We rotated the throttle body open by hand, and found a small rock sitting on top of the set screw. Removing this rock corrected the fast idle. We were stunned at what this meant. The fast idle had not been caused at the time of transmission failure. In fact, the fast idle could have existed for over three weeks, for all we knew, since we hadn’t seen the truck in almost a month. It was now clear that this tiny rock, along with an oblivious driver, had succeeded in destroying a perfectly good transmission. We deduced that the high idle had caused excessive fluid shear in the torque converter, particularly while stopped in gear. After picking our jaws up off the floor, we called Oregon Transmission Center, and told them what we had found, and asked them to bill us for the rebuild. It certainly wasn’t right that they should have to warranty a transmission that they had done an excellent job on the first time. Our real dilemma was the customer, who had mentioned that they did not want to spend any more money on this truck, and would probably get rid of it soon after it was returned. We have an excellent relationship with this customer, and thanks to their aging fleet (and their drivers), as well as their commitment to maintenance, their work had become a significant portion of our total sales. We decided that we would rather eat the full expense and labor of the repair than risk damaging this relationship, so we carefully explained the situation, and completely warranteed the job. The owner of Oregon Transmission Center was so amazed by our honesty that he gave us a significant discount. We told him that we were so relieved that they were not to blame, given their excellent work through the years, that it was a small price to pay.
It amazes me the many lessons that can be learned from a single job. This job was a big reminder that drivers can be completely oblivious to major problems with their vehicles. It was also a reminder that quality work, both in our shop and by those specialists we trust, is worth so much more than any warranty ever will be. Above all, honesty and clear communication is what makes any shop stand out. A small rock, paired with an oblivious driver, had put the truck and its occupants in a near life-threatening situation, and risked damaging our relationship with a large customer and our beloved transmission shop.
A dime-sized rock doesn’t seem quite so insignificant anymore.
Rob Gaskell, Jr.
Account Manager
Fleet Service Northwest | |
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