Positive Crankcase Ventilation: Description and Operation

CCV System:

PURPOSE
The Crankcase Ventilation (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 on the valve cover. The nipple contains a 2.2 mm orifice that meters the amount of crankcase vapors drawn out of the engine through the valve cover. A hose from the air cleaner that is connected to the other side of the valve cover supplies fresh air from the air cleaner to the crankcase.

OPERATION
The CCV system is similar to a conventional Positive Crankcase Ventilation (PCV) system, but does not use a vacuum controlled valve.

When the engine is operating, vacuum from the intake manifold draws on the metered orifice 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 outlet nipple. The vapors are consumed during combustion.