Positive Crankcase Ventilation: Description and Operation

Positive Crankcase Ventilation (DOHC):

SYSTEM DESCRIPTION

The PCV system mixes blow-by gas and oil vapors from the crankcase with fresh air, and directs the mixture to the intake system to be burned in the engine. The system consists of a PCV valve, a baffle to separate oil droplets from oil vapor, and a vent to the air cleaner. The PCV valve regulates crankcase vapor directly into the intake manifold. The vent to the air cleaner, under normal operation, allows fresh air into the crankcase to mix with the vapors before being drawn into the intake system. When there is too much blow-by for the PCV valve to handle, such as wide open throttle operation with heavy engine load or worn piston rings, the excess blow-by is vented to the air cleaner where it is drawn into the intake with the inducted air, thus keeping a completely closed system.