That makes sense, THANK'S Larry.

Vacuum is a volume where the pressure is much less than atmospheric pressure. When one draws from a larger amount of gas and particles formed Vacuum. Crankcase gives opposite of Vacuum, then press. So in the intake manifold, you get a craving forming Vacuum, the crankcase, you get a pressure in excess of air to be evacuated.

Drives: Mercury Montclair 1957th

www.mercury1957.com

Ah yes, I knew that, I learned that the hard way when I had the cap not vented and on the nitrous I could make oil appear from under the valley pan gasket and elsewhere.

  Vic Correnti

Vic, you didn't ask me but I'll put my 1¢ worth in. I don't believe so. The crankcase is vented to the atmosphere (thru the oil filler cap or elsewhere) in a PCV system and the PC valve is considered a 'controlled' leak.

So I agree with John, No.

"The Master Cylinder"

Enjoying life at the beach in SOCAL

John, what if you have a PC Valve doesn't that create a vacuum in the sump which could cause a leak from the gasket?

  Vic Correnti

No.

John - "The Hoosier Hurricane"

If the gasket on the lifter/pushrod cover is leaking, will it cause a vacuum leak?