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      03-13-2021, 10:53 PM   #91
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Drives: 2008 M3
Join Date: Oct 2012
Location: Davis, California

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Originally Posted by Helmsman View Post
Originally Posted by GearKid View Post
Here's my latest thought that may explain this stripped rod. Let's say a former owner swapped out the bearings at 45k or something like that. New OEM bearings and bolts go in. This rod and maybe the others were significantly over tightened. Maybe instead of 130 degrees they were tightened to 130Nm or ft-lbs. this was not enough to strip the threads initially but after running the motor for 30k miles the threads start to break loose. The rod holds together because the upper threads keep the bolt from pulling out. Everything stays tight until the current shop pulls it all apart and starts to tighten down that rod again. The tech gets only half way to spec when those threads completely fail.
If this is true then we may see similar issues as motors are opened up a second time.
I would also desperately be looking for a reasonable explanation when being in a tight spot between what seems to be a proper shop and the result. But this can't be that logical answer in my mind. If the bolt was that bad over tightened, it wouldn't make sense that 1) The tech didn't notice, and if he did, just put the engine back together. 2) The thread started to break loose and still kept up fine just to fall apart at second run.
There is a reason to why the rod bolts are extremely strong, holding back the highest load in the engine. If thread where broken I believe the cap would have started to move resulting in significant signs.

I know the situation when debating with people who have plenty more experience and knows better than yourself, while obviously still are quite able to make mistakes. Getting them to admit is...challenging. Have a similar story with a boat yard reg my boat, plain aweful but we can't take the blame for others shit bro.
"You should not win the argument, because you are a superior arguer.
You should win the argument, because your argument is superior."

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