The Stovebolt Site Forums The Shop Area Engine Shop Oil leak

I have spent consideral $$ to fix a rear main seal. Still leaks. The mechanic said the journal was pitted and that was the cause. I looked at it and could see a couple small pits. The oil leakage is still making a 1/2 cup puddle on the floor every time I drive it not to say on the tailgate and undercarrage. Was the seal put in wrong or is he telling me the truth?

Is it a lip seal or a rope? It's difficult to install a lip seal wrong, unless it's put in backwards. Rope seals are a whole other story, but when they're installed right, they're more tolerant of minor pitting than a lip seal.
Jerry

Are we talking about the 350 crate motor in your truck description?

You know, I dont really know what it is..block #'s say it it a 78+ crate 350 engine/

Somebody else will chime in but I can't imagine that having a rope seal. It shouldn't be leaking at all.

It doesn't have a rope seal for sure. I saw it when it was being installed.

I was not aware you were talking about a bent engine. Was the seal installed with the lip facing toward the crankcase? There are small angled lines molded into a lip seal that serve as wipers to channel oil back into the pan. If it's installed with the lip facing the outside, these wipers will force oil past the seal, and cause the problem you're describing.
Jerry

Are you sure its the rear main leaking. Often the valve covers, intake manifold, or oil sender can leak & run down looking like a rear main leak. I cant seem to get good VC gaskets anymore. You keep tightening them down & the gasket just squeses out.

Hard to do wrong with the seal itself on the SBC but some other places of intrest in the area that can be mistaken at a glance for a seal leak.
Where the rear main cap meets the block there should be no burrs or "bruses" or the oil will find it's way through and appear at the main seal area.The factory started sometime to apply sealer in this joint--telling me they had a significent amount of trouble there as they don't spend a dime for sealer unless it benefits them.
Also, before 90's the obsession of the builder with thinner and lighter gave us some sheet metal covers and pans poorly designed and so thin the sealing surface could be rendered unusable by less than careful removal.I have been bitten by this booger and gave a proper cussing for my own better feeling.
I think this is your most likely source of leak.
Block up the vehicle and run it withyou underneath to view the area after cleaning up the wet area with spray brake cleaner.
Good luck

Good points, particularly the advice about the back of the intake manifold and the valve covers. Power wash or steam clean the back of the engine and bellhousing area, then run the engine and look for wet spots.

OIL LEAKS DO NOT RUN UPHILL!

If there's any area that's wet higher than the center of the crankshaft, you probably don't have a crank seal leak.
Jerry

A 1/2 cup leak per outing should be pretty easy to find. The highest point (most upstream) of oil is the source. In the case of my SBC powered roadster the "rear main seal" oil leak was traced back to a partially squeezed out valve cover gasket.

Good points all.. Will check and get back with you next time it is warm enough to try it. Thanks