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      05-20-2025, 03:21 PM   #145
BimmerRob08
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Drives: 2008 M3, Space Gray
Join Date: Mar 2008
Location: KIKR (ABQ), NM

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I got a question. Althogh it’s pretty clear from some videos of the upper no.1 main bearing is wearing faster due to the up-load of the front of the crank due to the dual chains pulling on it from the tension. That part seems to be very plausible from the wear. But increasing the tolerance to allow more oil flow may help with lubrication but does that not also allow slight more bounce or flexing of the shaft? I’m sure minute difference but the front of the crank shaft is putting unequal about of pressure as it spins in the no.1 bearing area.

Has anytime that rebult and replaced the no.1 bearing with larger clearance seen any engine failures later? In other words; does this remedy fix the problem? Almost seems impossible to get 200K + miles with out major overhaul, etc.
Appreciate 0