Hey guys, I am not very knowledgeable about engines. I was wondering how hard it is to rebuild an engine that had the main bearing spun. When this happens...does the block get damaged??
I plan on working on n engine with this problem. I just want to mainly learn on it but if I ca build it up I will. I can't wait to get started.
ANY info you can provide please do.
Thanks

 

well yes there can be damage and more thanlikely there is but nothing a skilled amchinist couldn't handle... what did you have n mid when you say building it?

 

depending on damage, you might have to use oversized bearings.

 

You might have to get the block line bored as well if the damage is bad.

 

Thanks guys. I appreciate the help. I can't wait to get started.
I was planning on bopring it out a little and putting in bigger pistons. Not sure what else to do to it.

 

You can't run forged pistons in an H23 without iron sleeving the block. FRM strikes again!

 

how many miles did it have?

 

I think you meant undersize bearings? when you regound the crank, you go undersize right?

 

ANY time u spin a main bearing u have to get it line bored or it will just spin again..

 

anyone have pics of a spun bearing??

 

Does anyone know the reason H motors seem to spin so many bearings?? It seems everywhere you look there is someone selling a H motor with a spun bearing, or some is asking how to fix it. Why is this happening so much, espically compared to B motors, where this is very rare.

 

I noticed that too. What actually causes that. I know my friend was worried about that happening in his new M3.

The motor I am looking at has 150K miles on it.

 

Well usually lack of oil causes spun bearings, but Im wondering if anyone knows a little more on why its just these H motors causeing this

 

Because alot of them are being modded the f@#k out. Once it has been taken apart and NOT rebuilt right (as of clearances, torque specs, cleanliness, maintenance, etc.), such problems tend to occur. Cleanliness is a very important factor when it comes to putting these things back together; many people don't take extra precautions when it comes to "little" things like bearings which are very critical to an engine's longevity, etc. That's why I use gloves and handle them bearings with extra care (like on the edges only) because a finger smudge from your hands on the bearing surface may contain harmful acid that could destroy the bearing's surface. Also a couple of specs of dirt lodged in-between the bearings could change oil clearances drastically. Even dirt coming from anywhere else can end up scouring your bearings and journals and f@#king up your oil pressure, etc.
I've seen many "stock" bseries last well over 150,000miles and still counting. Rebuilt engines could last as long if done right.

 

Hey guys, I THINK he said that the rod bearing was spun...not one of the main bearings. Does that make sense??? If so, is it hard to fix??


[Modified by AndyD, 3:37 PM 11/14/2002]

 

Luckily it wasn't the mains; now it's possible to replace those bearings(rod) with the motor still in the car even.

 

yea get a new crankshaft or have yours turned and replace the rod(s) that u spun the bearing with.. i have some if u want em..

main bearings usually spin due to excessive RPM and lack of oil pressure...

 

my bad mains


My good mains

 

That's good to hear. he said that the motor still runs. Is that a sign that the main nearings are all ok??

 

thank you.

 

people these days half assing it....