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      08-03-2024, 02:52 AM   #9
ab987
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Drives: 1M, 2xM3, X3M, 335i
Join Date: May 2020
Location: Seattle, WA

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2011 BMW 1M  [9.50]
2010 BMW M3  [9.60]
2008 BMW 335i  [9.25]
2020 BMW X3 M  [9.50]
Quote:
Originally Posted by drwankel View Post
Interesting and horrifying. Surely running a supercharger couldn't make this worse.... right? right?

Here's my take on it. Main bearing replacement on these engines is not anywhere close to preventative maintenance. It's nearly an entire engine rebuild.

I'd just run it until it pops and then put a rebuild in it. People on these forums are passing 200k, and while that video is concerning, people around here arent dropping dead from main bearing failure.

Drive the car. The mains probably do wear, but there just isnt anything you can do about it short of an entire rebuild.
Based on what "good" engine mains look like, it probably would. I recall we've seen multiple low mile (<70k) supercharged engines fail on this forum. Too much force pulling up on the front of the crank for how thin the journals are. Pulling up more certainly won't help things.

It's a very similar problem to rod bearings in timing but at a seemingly longer interval, some see it earlier than others, but until we see good engines being torn down without copper showing on the front upper shell, I'm convinced it *will* happen to every S65 given enough miles. As we've seen, that can be 100k, 150k, even 300k, but at that point I think a lottery ticket is in order.

In my opinion, if you plan on keeping your S65 for the long term and you're nearing 150k miles, bite the bullet. Spend the $6-8k at a good shop like deans and don't look back. I'm $30k deep in a used engine and a full Carbahn rebuild, and that's not even a stroker. It's one hell of a gamble, up to you if you want to take it.
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