UPDATED… The major component in the Positive Crankcase Ventilation (PCV) system is the PCV valve, a simple spring-loaded valve with a sliding pintle inside. The pintle is tapered like a bullet so it will increase or decrease airflow depending on its position inside the valve housing. The movement of the pintle up and down changes the orifice opening to regulate the volume of air passing through the PCV valve. The PCV valve is typically located in a valve cover or the intake valley and usually fits into a rubber grommet. Also, read – What is an engine block? The location of the valve allows it to pull vapours from inside the engine without sucking oil from the crankcase (baffles inside … Continue reading What Does A PCV Valve Do? Best Answer