Positive Crankcase Ventilation: Description and Operation

View: Positive Crankcase Ventilation System:

PURPOSE
The PCV system routes blow-by gasses from the crankcase into the intake system so it can be burned in the engine's combustion chambers. A PCV valve regulates quantity of blow-by gasses based on intake manifold vacuum.

OPERATION
The PCV valve is operated by intake manifold vacuum. When running at idle, the PCV valve is slightly opened and a small amount of blow-by gas is drawn into the intake system. At higher speeds, the PCV valve is further opened and a larger amount of blow-by gas is drawn into the intake system.