Positive Crankcase Ventilation: Description and Operation

DESCRIPTION AND OPERATION
The positive crankcase ventilation system (PCV) prevents the escape of blow-by gases from inside the crankcase into the atmosphere.
Fresh air is sent from the air cleaner into the crankcase through the breather hose, to be mixed with the blow-by gases inside the crankcase. The blow-by gas inside the crankcase is drawn into the intake manifold through the positive crank- case ventilation valve
The plunger inside the positive crankcase ventilation valve is designed to lift according to intake manifold vacuum, regulating the flow of blow-by. The blow-by gas flow is decreased during low load engine operation to maintain engine stability, and is increased during high load operation to improve the ventilation performance.