Quote:
Originally Posted by craigs69
It is not the cheapest, simplest or most accepted fix, but a GZ vacuum pump took care of my leak that I had from day one on my street driven 469. Not a drop since the install in 2015. I will get flamed for proposing it, but it worked for me. End of story.
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There's no reason why building a vacuum in the crankcase should get you flamed. My preferred method for most gas engines is to seal the crankcase with the exception of one PCV valve to hook manifold vacuum to, resulting in a low pressure crankcase. This aids ring seal, helps eliminate small seeps, and reduces oil consumption overall. I run a catch can to trap nasty oil and moisture that I drain regularly.
Of course, this method works best on engines with lots of vacuum, but a vacuum pump is a great solution for a seriously cammed engine with low manifold vacuum.
Now having said all that, that's not the solution I would choose for a serious leak, or even as the primary solution to any seepage, but reality is that it will help, as you said.
The most common reason why rear main seals leak, in my experience, is improper installation or choosing the wrong seal. Fact is, neoprene rubber seals basically cannot seal properly on crankshafts with hash marks designed for rope seals. The only way to definitively get a neoprene rubber lip seal to work properly on such a crank is to have the sealing surface turned down smooth to remove those hash marks. This of course presents a problem, as the seals are designed for a given diameter sealing surface, so if you turn it down too far the seal still won't work. On Buick engines this is easy, as the guys have figured out a specific diameter to turn it down to and then a certain seal to use from a different engine that works great. Unfortunately I'm not aware of such a solution on Pontiac V8s.
I have installed many rope seals in many engines over the years, including Pontiacs, and they always seal for me, at least for a good amount of time. The seal I installed in my 212k mile 455 was still dry three years and 30k+ miles later when I pulled that engine.
The trick is to really pack it in the groove tight. I generally don't trim off much excess. I make sure the grooves in the cap and block are absolutely bone dry, I use a Q-tip or something to apply a THIN layer of GREY silicone to the inside surface of the grooves, then I pack the seal in dry. I let it cure for 24 hours. Then I smear a thin layer of grease on the rope and on the crank surface, bolt it all together and they just seal. Haven't had one fail on me yet using this method, again on Pontiacs and other engines.