A Bad Design

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I had a job to change the air conditioning compressor on a 2002 Toyota Avalon. This was a good customer and I wanted to do the job properly. At first the A/C compressor removal and replacement job looked pretty straight forward. I found out later that this was not the case. The problem was that Toyota did a terrible design job of mounting the A/C compressor. Four bolts held the compressor on the engine. The two top bolts connected to the block. The two bottom bolts connected to the oil pan. The oil pan assembly is a two piece setup. The bottom piece is the actual oil pan. However, this bottom oil pan bolts onto a middle piece which then bolts to the block. This middle piece is made of aluminum. And this is the problem. The two bottom bolts which braced the A/C compressor to the engine connected to this middle oil pan. The bolts are steel and the middle oil pan is aluminum. Whenever you have steel bolts threading into aluminum there is a big chance for problems. Especially when the assembly is exposed to heat and corrosion. The bolts over time can easily freeze under these conditions. My A/C compressor replacement job on the Toyota Avalon had this exact problem. The two bottom bolts were frozen into the middle oil pan. I bought another used middle oil pan from a wrecking yard and installed it. However, when I tried to install the new A/C compressor, once again I had problems with the steel bolts in this middle oil pan. The aluminum threads on the oil pan stripped. I ended up having to helicoil the two holes in the oil pan I just bought. Steel bolts in aluminum threads is a BAD idea. The A/C compressor job turned out to be a major pain. Toyota did a terrible job of designing the mounting setup for the A/C compressor on this V6 engine on this 2002 Avalon.

You learn something new every day

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I had a customer with a 2002 Infiniti I35 with a problem. The car would just stop accelerating while driving and go into idle. If you let it rest a few minutes and it would be OK for several more miles. If you cleared the fault codes on the engine ECU it would be OK for about 100 miles. But after this 100 miles it would continue to have this same loss of power problem. I tried changing many different components. I changed the throttle body, MAF, electronic power control (the accelerator pedal), spark plugs, VIAS solenoid, and a few other parts. I tightened all the electrical connections especially the grounds. I checked to make sure all electrical components had a good connection. Still, I could not fix the problem. The customer was tired of spending money and not having any good results. Several months down the road the Infiniti just plain stopped running all together. It died in the middle of the road. But this actually turned out to be a good thing. Because finally I was able to diagnose the original problem. The battery was totally dead. The alternator had stopped charging and was bad. This alternator problem turned out to be the answer to the loss of power problem all along. I was stumped because usually when an alternator goes bad, the battery gets drained of all of its power. The dead battery is always how you diagnose a bad alternator. But in the case of this Infiniti, the alternator was good enough to charge the battery but not keep the car running properly. You learn something new everyday. Max

Be careful of the valve job

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Many times a customer has come to me with a Volkswagen 20 valve 1.8T engine complaining that their cam sensor fault code was on. This engine has twenty valves and only four cylinders so timing is especially important. With five valves per cylinder, there is no room for mistakes. If you are only a little off on the valve timing, the cam sensor fault code will pop up. The customer state that they have checked the timing belt specifications over and over and still this code comes on. The answer is that most of these customers have just had their cylinder heads rebuilt. They have just had a “valve job”. The machine shops that have done this valve job have not set the chain that connects the two cams on the head properly. This chain and the two cams must be exactly on the timing marks. Most machine shops are unable to set the cams timing properly. So consequently, no matter how perfectly the timing belt is set,  the cam sensor fault code will pop up. The moral of the story is be careful when you go to get a valve job with a multi valvehead. MAX