Positive Crankcase Ventilation: Description and Operation

PCV System Diagram:

GENERAL INFORMATION
The positive crankcase ventilation system is a system for preventing 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 crankcase ventilation valve.

PCV Valve:

The positive crankcase ventilation valve is designed to lift the plunger according to the intake manifold vacuum so as to regulate the flow of blow-by gas properly.

In other words, the blow-by gas flow is regulated during low load engine operation to maintain engine stability, while the flow is increased during high load operation to improve the ventilation performance.