: Main Bearing Replacement?



Lawrence
02-21-04, 02:52 PM
1994 STS 73K miles

I am going to separate the case halfs for a seal replacement, not leaking but the motor is already out for head gaskets.

Is it advisable to replace the main bearings, since half of them will aready be out? Or is it something that is better left alone?

No problems I am aware of, just debating replacement as a precautionary measure.

Thanks,
Lawrence

BeelzeBob
02-21-04, 11:09 PM
1994 STS 73K miles

I am going to separate the case halfs for a seal replacement, not leaking but the motor is already out for head gaskets.

Is it advisable to replace the main bearings, since half of them will aready be out? Or is it something that is better left alone?

No problems I am aware of, just debating replacement as a precautionary measure.

Thanks,
Lawrence
You can use the main bearings over again. They should be perfectly fine.

If there is no leak I would leave it alone, personally. If it is not leaking then it is not likely to start at this point. And case half leaks or more like seepage that is not catostropic....so it is more a nuisance if it comes later than anything. Taking the entire lower end apart, even if the engine is out, is a bit of a risk.

If you do, be aware that there are superceded lower crankcase side seals, rear main seal and the use of the aneorobic sealer as a redundant seal on the lower crank case joint was incorporated after your engine was built so it should be added. A service manual and service bulletins would help with that.

zonie77
02-22-04, 01:06 AM
Lawrence,
Was that a service replacement engine? Do you know when it was installed?

Lawrence
02-22-04, 05:39 PM
Zonie77, yes it is. Installed 03/97. It has 73K miles on it. Under the valve covers it looks as clean as the day it was built.

bbobynski..... the thing is, I am just not sure if it is leaking or not. The side rails seem to have been "seeping" a very small amount, certainly nothing to worry about. The two areas that concern me are the back and front because I cannot positively ID them. With all the oil coming down from the top in back the whole bell housing area area is wet. There is some long term "heavy seep" all around the front. I couldn't say if it is a timing cover seal/gasket or the case half seal behind it. I agree, I am reluctant to seperate the case for fear of bearing failure, but if after I install it, it leaks.............

I had panned on anerobic sealant whether GM recommonds it or not, but it is nice to know they do recommend it. Marine outboards too use a split case captive seal design. From the factory most were not liquid sealed. Except, on the two strokes, they would leak in more than out. On these motors I wouldn't hesitate to seperate the case halfs and reassemble, they are needle bearings. But I am just not sure the ramifications of these automotive bearings.

Does GM recommend anerobic sealant be used on the oil pan as well?

BeelzeBob
02-22-04, 09:10 PM
Does GM recommend anerobic sealant be used on the oil pan as well?

No....but you can use it anyway.....