Positive Crankcase Ventilation: Description and Operation

Typical PCV System:

The Positive Crankcase Ventilation system cycles crankcase gases back through the engine where they are burned. In a typical system, the PCV valve regulates the amount of ventilating air and blow-by gas to the intake manifold and prevents backfire from traveling into the crankcase. On some engine applications, the PCV system is connected with the evaporative emission system.