Positive Crankcase Ventilation: Description and Operation

Fig. 53 PCV System Hose Routing:

A crankcase breather is attached to the drivers side of the engine block, containing a baffle system to separate the oil from the crankcase vapors. Crankcase vapors are vented through the breather on the block and the valve cover.
During periods of high intake manifold vacuum, crankcase vapors are drawn into the intake manifold from the top of the valve cover, through a restrictor. When the intake manifold vacuum is low (high load, full throttle) the crankcase vapors are drawn, unrestricted, into the air filter housing. The crankcase vapors are then drawn into the engine and burned.
When checking or making adjustments to the air/fuel mixture, the hose at the breather housing and the hose at the valve cover must be disconnected and open to atmosphere for accurate adjustment.