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leftybass209 · 02-02-2015, 01:58 PM

I can't speak for crankcase pressure and it's specific influence on the rear main seal, but what does have a lot to do with that leak is the initial design of the seal and a super clean surface with properly placed sealant, which is not impossible, but hard to do on your back with the engine in place. Too much or not enough sealant can cause a leak, time can cause a leak, and a worn crankshaft in that area (not highly likely but probable depending on it's age and use). I also run a PCV and a breather.

02-02-2015, 01:58 PM	#12
leftybass209 Registered User Join Date: Feb 2011 Location: Modesto, CA Posts: 2,189	Re: 69 350 motor I can't speak for crankcase pressure and it's specific influence on the rear main seal, but what does have a lot to do with that leak is the initial design of the seal and a super clean surface with properly placed sealant, which is not impossible, but hard to do on your back with the engine in place. Too much or not enough sealant can cause a leak, time can cause a leak, and a worn crankshaft in that area (not highly likely but probable depending on it's age and use). I also run a PCV and a breather.