What causes crankcase pressure?
Thread Starter
Melting Slicks
Joined: Mar 2002
Posts: 3,193
Likes: 0
From: Pittsburgh PA
What causes crankcase pressure?
My PCV valve keeps popping out of the valve cover, spraying my engine bay with oil. The valve is tight and shouldn't be coming out. Does anyone know what causes this or how it can be solved?
Thanks!
Thanks!
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Crankcase pressure comes from the explosions above the pistons. A little bit sneaks by each power stroke (blowby). This gas ends up in the crankcase and if it has no where else to go, it builds up pressure.
Is your PCV valve inserted in the right direction? It's kind of a one-way valve. I'd also check to make sure it isn't plugged.
Is your PCV valve inserted in the right direction? It's kind of a one-way valve. I'd also check to make sure it isn't plugged.
Drifting
Joined: Nov 2002
Posts: 1,688
Likes: 201
From: Loveland, CO
If the pressure build up in the crankcase is more than the PCV can suck out, you have a problem. A leak-down test will help isolate the problem. It is similar to a compression test but more diagonistic. Usually excessive blowby the piston rings will pressurize to crankcase above normal levels. 
