Crankcase Filter: Service and Repair

Crankcase Ventilation Valve Cross Section:

PURPOSE
The Positive Crankcase Ventilation (PCV) valve is used to route crankcase vapors to the intake manifold.

PCV System:

OPERATION
The PCV valve is the primary control which meters the flow at a rate depending on manifold vacuum. To maintain idle quality, the PCV valve restricts the flow when intake manifold vacuum is high. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase vent tube into the air inlet duct to be consumed by normal combustion.