Given the complexity of modern cars, wouldn’t it be nice if our customers really believed we were magicians, and that we never make mistakes while fixing their cars? Sure, it would be nice but the fact is that we are not infallible magicians, even if we sometimes think we are. We have all made mistakes and we will continue making them, but when viewed objectively, our disasters teach us (or should do) something about ourselves, our approach to our jobs, but more importantly, our willingness to learn from our mistakes.
The following list of this writer’s mistakes, who is an experienced mechanic, and until recently, also a repair shop owner will not only describe some mistakes that could have been avoided, but also some lessons that should serve to prevent these and similar disasters befalling anyone else. Let us start with-
The Turbocharger That Should Not Have Been Replaced
This disaster was actually a series of mistakes, all of which could have been avoided, and all of which were committed by me because despite my experience, I chose to believe what a new client told me, without verifying the “facts” as he presented them.
The client was new to me, and the vehicle was a 2.5 turbo diesel Nissan Hardbody pick-up truck that was towed to my shop. According to the client, the truck suddenly lost power the day before, and he suspected that the turbo charger was the cause of the problem. I checked, and sure enough, the compressor wheel had disintegrated. Showing him the pieces I had retrieved from the turbo, the client asked if we could replace the turbo charger.
I agreed to take on the job, but seeing that the vehicle had close to 300 000 km on the clock, I also insisted that before I could do that, I have to inspect both the main and big end bearings, as well as perform a proper compression test, as is standard procedure when replacing a turbo charger on a high-mileage engine.
Long story short; the client said that the engine currently in the truck was a rebuilt unit that had done less than 50 000 km, that it used almost no oil between services, and that it ran as smoothly as a proverbial Swiss watch. Since there were no excessive oil deposits in the old turbo or the inlet ducting, I chose to believe him, which was my first mistake.
Fast forward a few days. With the new turbo installed, I started the engine but something was not quite right; there was a general “noisiness” about the engine, and the idling quality was not quite what it should have been. Raising the engine speed produced no smoke from the exhaust, so I called the client to come collect his truck. When the client arrived, he told me that the noisiness and the rough idle were present since the “new” engine was installed, and that I should not worry about it- he was aware of the issue, and that he accepts responsibility should anything go wrong. I believed him again, which was my second and third mistakes, the third mistake being not making the client sign an indemnification.
Two days later however, the truck was towed back because it had lost power again but this time, oil and coolant poured out of the inlet ducting when I checked the condition of the new turbo. The client insisted that I screwed up since I had obviously overlooked something, and that he was instituting legal proceedings against me with the aim being to get a new engine out of me. At this point, I got my insurers involved, who recommended I do nothing until they had inspected the engine, which they did few days later.
Their inspection of the engine showed that I had indeed screwed up. The wear patterns on both the big end and main bearings proved that the engine had done about 300 000 km, but worse, they simply checked the engine serial number against the VIN number, which showed that the engine in the truck was the engine it had left the factory with.
The conclusion was simple; the worn bearings could not cope with the full boost pressure of the new turbo, which caused them to fail, which in turn, caused a connecting rod to break and poke a hole in the block between two cylinders.
Lessons learned:
This incident was by far my worst mistake ever, and although my insurers paid for the replacement engine, the fact that I was very busy at the time this disaster occurred is no excuse. I should have made the time to perform the basic and required checks on the condition of the engine, I should not have taken a new client at his word, and I should have made the client sign an indemnification against subsequent damage.
At the very least, I should have confirmed that the engine in the truck was a replacement as the client had claimed, and not the original. After all, it took my insurance company all of two minutes to prove that the client had lied; if I had done the same, I would have refused to take on the job.
Renault Scenic Auxiliary Belt Failure
In this case, which qualifies as my second-worst mistake, the failure of a new auxiliary drive belt destroyed all the valves on a 1.9L Renault Scenic diesel engine.
The job was simple; an existing client wanted us to replace the auxiliary drive belt and tensioner on his vehicle because he had noticed some fraying of the belt a week or two before. We had never worked on this particular vehicle of his before, but how difficult can it be to replace an auxiliary belt, right?
I kept the vehicle in the shop, ordered OE parts from the dealer, and when these arrived, I decided to do the job myself, and not assign it to a mechanic as I had planned to do. Later that day, the client collected his vehicle, paid his bill, and left on a trip to a game reserve he had been looking forward to for weeks. However, a couple of hours later, the Renault Scenic arrived back at the shop on a flatbed recovery truck, and the client presented me with what looked like a crow’s nest of tangled remains of what was clearly an auxiliary belt.
Investigations showed that the new belt had somehow disintegrated, but worse, some of the strands had worked themselves into and under the timing cover, which then dislodged the timing belt, which in turn, caused the pistons to slam into the valves. Further investigations showed that the water pump pulley was severely out of alignment, which should have been obvious even to a rank novice. Clearly, the additional tension of a new tensioner forced the pulley further out of alignment, which was what had destroyed the new belt.
The client was not at all happy about this, and although he accepted that mistakes and oversights happen, he did insist that I provide him with a vehicle so that he could continue his holiday in the game reserve. The combined cost of the rental vehicle and the repairs to his engine amounted to a small fortune, but there was nothing to do about it but pay up, since the fault was 100% mine.
Lessons learned:
I should have checked the pulley alignments, or at the very least, I should have verified the repair after it was done. If I had, I would have noticed that the water pump was damaged, and I would have replaced it as a matter of course. As it turned out though, I did none of these things, which cost me a fortune in unnecessary repairs.
BMW M42 Engine- Camshaft Failure
In this disaster, a camshaft on a M42 BMW engine failed because I had switched the cam boxes around.
The job was a simple head gasket replacement, but since I always told myself that I needed to keep my hand in, I elected to do this job myself. However, when the cylinder head arrived back from the machine shop, I noticed that the inlet and exhaust cams were switched, but before I could switch them back, the phone rang, and I spent the next hour or so with a particularly talkative client.
Back on the job, I torqued the cylinder head down, but for reasons that are not entirely clear to me even now, I failed to remember that I needed to fit the right camshaft to the right cam box, and proceeded to install and tighten down the camshafts. I installed the cam alignment tool, fitted the timing chain, but again for reasons I still can’t fathom, I failed to notice that something was not quite the way it should have been. The cam lobes on cylinder #4 did not quite “rock”, but despite this, I removed the flywheel locking and cam alignment tools, closed up the engine, connected everything, changed the oil, and turned the key.
The result was not what I expected. A load bang issued from the inlet manifold, and although the engine started, it ran on only three cylinders for a few seconds before shutting off. Investigation showed that I had bolted down the exhaust cam box on the inlet side, which closed off oil passages to the camshaft, which caused the camshaft to seize, which in turn, caused the camshaft to break.
Lessons learned:
Do one thing at a time, and take the time to verify the fitment and location of parts before bolting anything down.
The Brake Pads That Would Not Fit
While some mistakes are serious and cost a fortune to rectify, others are mere annoyances that occur for reasons that defy description or belief, as was the case of the brake pads that would not fit because I had failed to retract a caliper piston fully.
This happed during an especially busy time, and since everyone in the shop was busy with their own problems, I decided to do a quick brake pad replacement myself. The vehicle was an immaculate Ford Cortina MK 5 that belonged to a long-time client, so I invited him to wait for his vehicle.
Since I carried these particular brake pads in stock, I whipped off the wheels, removed the calipers, pushed the pistons back with a modified G-clamp, and installed the new pads but for some weird reason, the caliper on the left side would not fit over the new pads. I checked the new pads or size, dimensions, and thickness against the catalogue, but for the life of me, I could not get the caliper to fit. Rather stupidly though, I thought that a touch on the belt sander might remove some high spots on the pad (that were clearly not there), so I sanded about a millimetre or so off the pad, but the caliper still would not fit.
Even more stupidly, I removed progressively more friction material until the pad had lost about 50% of its thickness, at which point the caliper slid over the new pads. It was also only at this point that I noticed that the calliper piston was not fully retracted.
Lessons learned:
This fiasco only cost me a new set of brake pads to fix and although it did not teach me anything, it did remind me of the fact that if you are doing the same thing over and over but you get the same undesirable results every time, you are doing something wrong.
Removing The Wrong Cylinder Heads
Two of my long-time clients are twin brothers, and they have identical 3.7L V6 Jeep Cherokees- the same colour, the same trim, the same wheels, and even the same ancillary driving lights. In fact, the two vehicles are identical in all respects, with the only difference being their licence plate numbers.
Nonetheless, one day it happened that both brothers arrived at the shop together; one for a routine service on his vehicle, and the other with a blown cylinder head gasket, on his. Being busier than usual, I asked a mechanic to park both Jeeps under the shade netting outside the shop, and to start the service on the one Jeep as soon as his bay was free. I decided to do the cylinder head job myself, being somewhat of a Jeep specialist.
However, six hours later, I discovered that neither head gasket was blown. Soon after, the other mechanic reported to me that he had completed the service, but that this Jeep had a very rough idle, and maybe we should let the customer know about it.
Investigations revealed that I, and the other mechanic had each done the right thing- but on the wrong vehicles, and it was entirely my fault.
Lessons learned:
The lesson to be (re)learned from this fiasco is this- get your facts straight, verify all faults, and verify them again before starting a major repair procedure.
In this case, I broke my own rule never to start work on any vehicle before all the paperwork was complete, and that the faults listed on the work order are verified. In this case, however, I had completed the paperwork, but placed the wrong work order in the wrong vehicle, a mistake that was compounded by the fact that the two vehicles were identical in appearance, which is of course, no reason to make an idiotic mistake like removing the cylinder heads from the wrong engine.
