Positive Crankcase Ventilation: Description and Operation

PCV Flow:

SYSTEM DESCRIPTION

The PCV system used on this vehicle does not provide a fresh air breather for the crankcase. The PCV system consist of primary and secondary circuits. The primary circuit consists of a calibrated orfice attached to the intake manifold, just below the Throttle Body Injection (TBI) unit. A small hose runs from this orfice and is attached to a larger (secondary circuit) hose, which connects from the cam carrier to the bottom of the air cleaner housing.

At idle and part throttle conditions, all gases and some fresh air from the air cleaner are directed through the primary circuit orfice, which is subject to manifold vacuum. Under heavy load or wide open throttle conditions, a small amount of the gases are passed through the primary system orfice. The majority of gases are passed through the secondary system, at the bottom of the air cleaner housing, and are burned in the combustion chamber.