Q: What is the purpose and components of the Positive Crankcase Ventilation (PCV) system and PCV Valve?
A: The Positive Crankcase Ventilation (PCV) system cycles crankcase vapors back through the engine, where they are burned. The valve regulates the amount of ventilating air and blow-by gas to the intake manifold and prevents backfire from traveling into the crankcase. The PCV system consists of a replaceable PCV valve, a crankcase ventilation filter, and connecting hoses. The air source for the crankcase ventilation system is in the air cleaner. Air passes through a hose connected to the air cleaner housing and to the oil filler cap. From the oil filler cap, the air flows into the valve cover and the crankcase, from which it circulates up into another section of the valve cover and finally enters a spring-loaded regulator valve (PCV valve) that controls the amount of flow as operating conditions vary. The vapors are routed to the intake manifold through the crankcase vent hose tube and fittings. This process goes on continuously while the engine is running. Checking procedures for the PCV system components are included, and component replacement involves simply installing a new valve or hose in place of the one removed during the checking procedure.