Positive Crankcase Ventilation: Description and Operation

PURPOSE
The Positive Crankcase Ventilation (PCV) system directs crankcase "blowby" to the intake system in order to prevent vapors from escaping to the atmosphere.
Components of the PCV system include:

^ Valve cover
^ PCV hose
^ Primary and secondary vent

Valve Cover Labyrinth:

OPERATION
The valve cover contains a "labyrinth/siphon" system that is bolted to the inside of the cover.

PCV Venting:

During idle or part throttle the flow rate is limited by a 1.8 mm restrictor in the secondary vent bore. During full-load operation, vapor flow transfers to the primary vent bore.