Quote:
Originally Posted by F30ed
If the above theory is correct (sounds logical to me), chain stretch and plastic guides destruction is a function of number of engine starts. If you start the car and drive for 8 hours every day without stop, you can make N20 to 200,000 miles without a single problem. If you use ASS(auto-start-stop), you may damage your chains dozens time a day, and failure may occur much much sooner. This may sort of explain why some people make to 110K with no problem and some have chain ripped at around 50K, and why some have chain noise and some not.
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Similarly, I wonder if it has to do with how soon you accelerate after starting. I've had my 328i for only a couple months, and in the first days when I was becoming familiar with auto start stop, I noticed that my normal driving habit from a stop was to quickly move my foot from brake to gas and accelerate. Driving that way with ASS, I felt more vibration and hesitation from the engine briefly. Perhaps it is the combination of low oil pressure in the tensioner when accelerating that prematurely wears the guides and chains. Meaning, ASS on its own may contribute to wear from additional engine starts, but it is stepping on the gas too soon that leads to catastrophic failure.