Main seal leak

[Ryanz]

My Blazer has been in the shop since April getting a rebuild done. Its now gone back in twice to have the rear main redone as it ends up leaking after a few hours of driving. This last time they put a double lipped upgraded seal after going through the entire motor with a fine toothed comb to ensure everything was proper. However, its just started leaking again. It's not much, just a couple drops overnight but enough to make you mad after spending all of the dough and having it in the shop this whole time. Starting to think I should have went with a Crate instead of rebuild. But, matching numbers (or period correct is best these trucks provide) had me convinced to keep it 100% stock. Anyone else feeling the frustration?

[BBrendal]

I thought all older Chevy motors are supposed to leak!

[Ryanz]

Well I was hoping not this early in the game - I've spent a lot of money to have it be leak free at least for a year or 2. :-)

[Blazerowner]

I put all upgraded gaskets in my sbc I had built a few years ago and it still had a small leak. I believe it was the rear main seal as well which was a one piece. All gaskets were nice reusable rubber and weren't cheap. The engine had a lot less leaks than stock. The older engines leak it's just their nature. It's one of the many reasons I'm going ls3.

[Anejo]

I'd respectfully have to disagree. I've pulled literally a hundred 2 piece sealed small blocks apart after a long service life and they were dry in the rear. Something's not right. A good machinist will get to the bottom of it rather quickly. Has the oiling system been modified? Some will limit valve train lube sending more volume elsewhere. Are the seals coming out damaged on inspection? A Melling M55 pump is all the engine would ever need in a street application. Double check that the bypass piston in the pump is not stuck. It should not be leaking.