Positive Crankcase Ventilation: Description and Operation

Typical PCV System:

The Positive Crankcase Ventilation (PCV) system vents harmful blow-by fumes from the engine crankcase into the intake manifold for burning with the fuel and air mixture. The PCV valve, located on top of the valve cover, varies the amount of blow-by gases fed to the intake manifold in direct relation to engine demand and serves to prevent combustion backfiring into the crankcase.

The amount of blow-by gas allowed into the intake manifold from the crankcase is controlled by the PCV valve. It is a one-way valve; it does not allow anything from the intake manifold to pass into the crankcase.

The benefits from the PCV system include the ability to:
- Maximize the oil cleanliness by venting moisture and corrosion from the crankcase.
- Protect against crankcase explosions
- Regulate automatically the ventilation of crankcase blow-by gases to the intake manifold in direct relation to engine operating conditions.