Pontiac Fiero engine question?

[petrolino2008]

I have a 1987 Pontiac Fiero , my mechanic installed a used engine from a different car, it ended up having a bad engine bearing. My mechanic installed a new set of bearings thru the oil pan, but it once again one bearing spun. Is there a way around fixing the bearing without having the engine rebuilt ? Another question is, It was a used engine that was put in from a different Fiero that was running perfectly fine before it was installed in my car. (previous owner of the engine had an upgrade installed) why would the transplant cause a spun bearing? Thanks in advance!

 

[melsg5]

Im assuming you mean main bearings as opposed to rod bearings? Sounds like the crankshaft is damaged and the engine has to be pulled and disassembled. The transplant should not have caused the damage, sounds like it was preexisting regardless of what they claim.

 

[Oreif]

You don't say if it's a 4-cyl or a V-6.

If it was a V-6 it could have been is that the used engine was from a 1988 Fiero or later GM 2.8L. The problem is the 1988 V-6's were internally balanced and the 1987 and earlier were externally balanced. If you used an externally balanced flywheel/flexplate on the internally balanced engine, It would unbalance the crank and eat main bearings. Did they use your flywheel/flexplate when the engines were swapped?

If so, You could locate the .5" X 1.5" weight on the backside of the flywheel and remove it. This makes the flywheel neutral again so it can be used on the later engines.

When they changed out the bearings did they mic out the crank and the main? The first spun bearing could have worn the surfaces down so a stock bearing isn't thick enough which would cause the new bearing to spin again. They do make over-sized bearings for this reason.