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GM 4CYL Main bearing cap installed wrong, what do you think?

1414 Views 6 Replies 4 Participants Last post by  Mr. P-Body
So I got a friend that thought he would be helpful and help me with my motor while I was at work, he knows the caps have to be put together a specific way but why he didn't DO that I don't know. Engine was all together when I got home and I got the honors of starting it - froze up

I had used assembly oil but left the motor sit a couple weeks so I thought maybe it was dry - shot a little oil in the cylinders and made 1 rotation without any difference, said this isn't right inspected the rods(fine) mains (2 backwards).

Would you guys think the bearings are okay with just 1 rotation? The dullness is somewhat polished on the edge of a couple bearings but all assembled it's snug, but turns much better now that they are correct; I am thinking the break-in would wear in the bearing beyond where it is now

Normally I would just replace the bearings but this is a marine engine and the mains are $140ish and I am way over the original budget!

3.0 181 Volvo Penta (4 cylinder GM block)
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If you have any doubt, it would be best to replace them now. I have not ever once got "lucky" when it comes to stuff like that. Did you check all clearances? You say the motor is a little tight after correcting the mains?
Lol, now that you put it like that, neither have I... Well I wouldn't say tight, it was tight, but nw I can turn it over now with a bar. With new cam main and rod bearings I would assume it would be a little snug the first few rotations?
If the bearing material isn't "peeled" from the backing, just "shined" a little, they should be fine.

New bearings should NOT make an engine "tight". in fact, we use what we call "the two finger test" for the mains. That is, once the mains are installed, lubed and torqued, you should be able to grab the snout of the crank and turn it with two fingers. Same with the rod bearings, but the friction from the pistons and rings WILL make it much tougher to "turn".

Where are you buying those bearings??? That's HIGH! About double what we sell them for, anyway. Federal Mogul part no. 4123MA-xxx. Same as the 153. They are NOT "marine specific".

Oh yeah I did forget to add new pisons and rings to that check list. That price is through Volvo and looking on eBay I did find the moguls for a lot cheaper. Now I'm just stuck with the decision to make.
Check the part numbers probaly the same parts just different box and name on box and your going to throw that away anyway.
Nothing "special" about any of the parts in the engine except the gaskets and expansion plugs. The gaskets are marine-specific. The expansion plugs need to be brass (where they seal the cooling system, not the cam plug or oil galleries). The rod bearings are the same as the 292 straight 6. ALL the parts are readily available through normal engine parts "channels". Be careful on E-bay. Avoid "old" packages. Bearings can corrode sitting on the shelf.

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