how much crank case pressure is to much
- Thread starter bearman
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Are you running a PCV valve and/or breathers on both sides of valve covers? A good ring seal usually limits crankcase pressure. I remember when my 360 was breaking in for the first few thousand miles it was pushing oil out of the breather but it calmed down once the rings sealed up good.
Rick62
Well-Known Member
There will always be some crank case pressure. If you don't use a PCV valve the pressure will come out someplace. Most likely in the form of oil vapor around the breathers on the valve cover. If you don't use vented breathers you may have problems with valve cover gaskets.
moper
Well-Known Member
All depends on the engine we're talking about. Best way to see how bad it can be is do a leakdown test. Required the right tester and a decent air compressor but will tell you what is leaking by. Then you can determine if that is too much... All engines have an amount of leaking by the rings. If you have a decent PCV system that is usually more than enough to deal with it. If you have persistent leaks, or oil vapor all over the engine by the breather(s), chances are there's something causing excessive blow by.
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too much blow-by is that which can't be sucked up by the pcv
451Mopar
Well-Known Member
Piston ring seal is a good place to start if you have excessive blow-by. You can use a leak-down tester to check the ring seal.
Venting the pressure with valve cover breathers is the easiest way to normalize the pressure and keep if from building up.
If you are using a crankcase evac system that connects to the headers, make sure the one-way valves are working.
Have a friend who kept splitting the valley tray on big block, found a bad one-way valve on the evac system that was blown and pumping exhaust pressure into crankcase.
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