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Discussion Starter #1
Hello everyone!
I just took apart engine after spun bearing and wondering if anyone has expirience in s62 crank repair?

There are 2 options:
1. to weld and grind it to nominal size:
-which is more expensive, at least 500$
-the only company i know in socal who are able to do that is marine cranckshafts - waiting time at least 6 weeks
-once they did crank for my s85 and it still runs great

2. to grind it for undersized bearings
- bmw has undersized bearings in catalogue +0.25 and 0.50
- crank shop i found nearby estimated 50$ to grind one rod journal - the guy said that he can try 0.25, but most likely damage is beyond that point so 0.50 is my option

So i have couple questions. I believe crank is hardened or has some coating on top of the journal, so is it ok just to grind it without any other proceedures? Also can i grind only 1 journal, or i have to do all 4? Will it affect to a stroke somehow?

Any opinions highly appreciated!
 

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Hello everyone!
I just took apart engine after spun bearing and wondering if anyone has expirience in s62 crank repair?

There are 2 options:
1. to weld and grind it to nominal size:
-which is more expensive, at least 500$
-the only company i know in socal who are able to do that is marine cranckshafts - waiting time at least 6 weeks
-once they did crank for my s85 and it still runs great

2. to grind it for undersized bearings
- bmw has undersized bearings in catalogue +0.25 and 0.50
- crank shop i found nearby estimated 50$ to grind one rod journal - the guy said that he can try 0.25, but most likely damage is beyond that point so 0.50 is my option

So i have couple questions. I believe crank is hardened or has some coating on top of the journal, so is it ok just to grind it without any other proceedures? Also can i grind only 1 journal, or i have to do all 4? Will it affect to a stroke somehow?

Any opinions highly appreciated!
Assume the scoring on the crankshaft was severe enough to the point that it requires this work?



Do you have any additional details on how/when you discovered the spun bearing ? And if you continued to drive on it afterwards?
 

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If you grind the crank to remove metal, won't you need OVERSIZED bearings?

Regards,
Jerry
 

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Discussion Starter #5
If you grind the crank to remove metal, won't you need OVERSIZED bearings?



Regards,

Jerry

I thought the same before I read that:
“An oversized bearing has the same inside diameter but a bit more material on the outside diameter. An undersized bearing measures the same outside but is thicker on the inside.”


Sent from my iPhone using Tapatalk
 

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Discussion Starter #6
Assume the scoring on the crankshaft was severe enough to the point that it requires this work?



Do you have any additional details on how/when you discovered the spun bearing ? And if you continued to drive on it afterwards?


I bought the car with knocking engine, so I was ready for it)


Sent from my iPhone using Tapatalk
 

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The crank will need to be heat-treated after grinding.
I think the best bet right now just to get a good replacement crank and go with standard bearings.
 

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The crank will need to be heat-treated after grinding.
I think the best bet right now just to get a good replacement crank and go with standard bearings.
Correct. Some argue that grinding down one size doesn't go through all of the existing heat-treatment, but I would never take that risk.

Agree that a replacement crank will be both cheaper and faster than sending it to Marine Crankshaft. If you do choose to use the existing crank, I would recommend the weld and re-grind approach rather than using (what I call) oversize bearings.

--Peter
 
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dranik182
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