Positive Crankcase Ventilation: Description and Operation

Typical PCV Air Flow Diagram:

CAUTION: Do not remove the PCV system from the engine. Operating engine without PCV system will reduce both fuel economy and engine ventilation. This will weaken engine performance and shorten engine life.

The Positive Crankcase Ventilation (PCV) system cycles crankcase gases back through the engine where they are burned. The positive crankcase ventilation valve:
- regulates the amount of ventilating air and blow-by fuel vapor to the intake manifold.
- prevents backfire from traveling into the crankcase.
- is mounted in a vertical position.