Positive Crankcase Ventilation PCV System

PCV System:

The PCV valve is operated by the intake manifold vacuum.
When the engine is running at idle, the PCV valve is opened slightly and a small amount of blowby gas is drawn into the intake manifold to be burned.
At higher engine speeds, the PCV valve is opened further, allowing a larger amount of blowby gas to be drawn into the intake manifold.