Quote:
Originally Posted by K-M3
In your experience ... is this another case of main bearing failure after rod bearing replacement AND does a rod bearing replacement ( with extra clearance bearings) lead to increased oil flow through the rod bearings but scavenges oil flow thru the main bearing leading to main bearing failure from oil starvation ??
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I don't believe that replacing the rod bearings leads to any faster rate of failure for the mains. I think that all S65 mains are wearing abnormally, and that the ones with mains that are
going to fail just happen to be failing about now as cars are getting to that mileage sweet spot. The only main failures I've seen in person were on stock blocks with original rod bearings.
I believe this is a clearance issue, compounded by variances in OEM tolerances. This is why some of the tighter built motors fail early on under 30k miles, and why some are lasting for over 100k miles and still going strong. Those high milers were built with clearance specs towards the looser side of BMW's spec. That's why I believe that redesigned bearings with increased clearances like BE are the solution.