wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
12/17/23 4:43 p.m.

Yo!  Wuts up GRM peeps?

 

So, my rx8 partially spun a bearing in my swapped 3.9 gm v6.  My fault.  I was low on oil.

Now, all the bearings look good except #6.  Had lots of bearing material in oil filter.

When I took the rod cap off, it had spun about 20 degrees.  Didn't overlap.

 

The crank has some visible marks on about 180 degrees of it.  The other 180 looks great.

 

So, what do I do?  There are bearings available in different sizes.

 

Can I get it polished?  Should I?  What does that do to my budget?  

 

Help me GRM, you're my only help!

Streetwiseguy
Streetwiseguy MegaDork
12/17/23 5:09 p.m.

No such thing as a partially spun bearing.  Crank needs to be measured, and either polished or machined.  The rod needs to be resized.  The block needs to be completely cleaned, and the oil passages cleaned.

Or, polish the crank, toss bearings at it and send it.  If it explodes, it's not a lot more expensive than what you already need to do.

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
12/17/23 5:13 p.m.
Streetwiseguy said:

No such thing as a partially spun bearing.  Crank needs to be measured, and either polished or machined.  The rod needs to be resized.  The block needs to be completely cleaned, and the oil passages cleaned.

Or, polish the crank, toss bearings at it and send it.  If it explodes, it's not a lot more expensive than what you already need to do.

I should clarify...  there was no overlap to the bearings.  Like they spun together.

 

I'm thinking find a good machinist and have them give me some advice too.

 

Thanks!

 

Keep the ideas coming.

cdowd (Forum Supporter)
cdowd (Forum Supporter) Dork
12/17/23 5:54 p.m.

Pilotbraden on here and I polished a a crank like that with a shoelace and very fine sand paper and replaced just the one bearing.  There are a bunch of videos on YouTube about it.  This was on an old Nissan pickup wood hauler.  It has been running fine since.

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand UltimaDork
12/17/23 6:07 p.m.
cdowd (Forum Supporter) said:

Pilotbraden on here and I polished a a crank like that with a shoelace and very fine sand paper and replaced just the one bearing.  There are a bunch of videos on YouTube about it.  This was on an old Nissan pickup wood hauler.  It has been running fine since.

I've spent a chunk of my day polishing a crank with a graduating series of wet sandpaper, 800, 1000, 1500, then 2000. When I get the whole thing done, I'll polish it with some metal polish on a strip of cloth diaper. 
 

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
12/17/23 6:57 p.m.

V8?  Sweet!

 

Did it have a bearing issue? 

Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) GRM+ Memberand UltimaDork
12/17/23 7:14 p.m.

In reply to wvumtnbkr :

Didn't have anything more than some wear, bearings actually looked surprisingly good for a 200k mile work truck engine. 
 I'm doing a rebuild for my challenge car. 

wvumtnbkr
wvumtnbkr GRM+ Memberand PowerDork
12/18/23 4:32 p.m.

I took it to a shop.  Quoted $150 to grind it.  I'll throw some new bearings and new head gaskets on it and then go rip on it again!

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