Positive Crankcase Ventilation: Description and Operation

Crankcase Ventilation System (CCV):

FUNCTION

The CCV system is used to prevent sludge build up in crankcase and prevent hydrocarbon emissions from escaping to the atmosphere.


CONSTRUCTION

The system consists of a fitting in the intake manifold connected to the outlet nipple of the oil/vapor separator. The nipple contains a 2.2 mm orifice that meters the amount of crankcase vapors drawn out of the engine through the oil separator. A hose from the air cleaner that is connected to the other side of the oil separator supplies fresh air from the air cleaner to the oil separator.


OPERATION

The CCV system is similar to a conventional PCV system, but does not use a vacuum controlled valve.

When the engine is operating, vacuum from the intake manifold draws on the oil separator causing vapors from the engine and fresh air from the air cleaner to mix. The vapor/air mixture is drawn into the intake manifold through the metered orifice in the oil separator outlet nipple. The vapors are consumed during combustion.