Positive Crankcase Ventilation Valve: Description and Operation

PURPOSE
The PCV valve is the primary component and the regulating agent of the positive crankcase ventilation (PCV) system.

OPERATION






Blow-by gas is drawn from the crankcase by intake manifold vacuum and crankcase pressure acting on the spring loaded PCV valve, which regulates the size of the opening through the valve.
At idle the passage through the PCV valve is very small, while on acceleration or during heavy load conditions the passage is fully opened.