Positive Crankcase Ventilation: Description and Operation

Crankcase Breather:

Crankcase Housing Breather Hoses:

PURPOSE
The crankcase emission control system vents crankcase gases back into the intake system.

CONSTRUCTION
The crankcase breather is attached to the side of the engine block. The crankcase breather opening is larger than on previous systems. The crankcase breather contains a baffle to separate oil from vapor and return it to the oil pan.

The breather hose contains a restrictor to control the flow of vapors to the intake manifold.

OPERATION
The crankcase emission system is a closed system. No gases are vented to the atmosphere.

When intake manifold vacuum is high, all crankcase vapors are drawn into the intake manifold through the restrictor.

When manifold vacuum decreases, part of the vapors are drawn through the restrictor while remaining vapors are drawn into the air filter housing.

NOTE: When checking or adjusting CO content, disconnect and plug the control valve hose.