Positive Crankcase Ventilation Valve: Description and Operation
DESCRIPTIONThe Positive Crankcase Ventilation (PCV) Valve, located next to the oil filler cap on the valve cover, meters air flow in the system at a rate that depends on manifold vacuum.
OPERATION
When the engine starts, the plunger in the PCV valve is lifted in proportion to intake manifold vacuum and the blow-by gas is drawn directly into the intake manifold. The function of the PCV valve is to restrict the flow of crankcase emissions when vacuum is high to preserve idle stability.
CONSTRUCTION
The PCV valve contains a spring-loaded plunger.