The PCV system is used to reduce the emission of hydrocarbon compounds into the atmosphere by removing crankcase gases. Purging is carried out by circulating fresh air coming from the air cleaner through the crankcase, in which it mixes with accumulated vapors and gases escaping from the combustion chambers and is discharged through the PCV valve into the intake manifold.
The main components of the system are the PCV valve, the purge filter and the set of vacuum hoses connecting these devices to the engine.
In order to maintain stable idle speed, the PCV valve shuts off the purge flow when the vacuum in the intake manifold is deep. In the event of a malfunction of the engine (as, for example, in the case of problems with piston rings) the system removes excess crankcase gases through the vent pipe to the air cleaner.
A description of the procedures for checking and replacing the PCV valve is given in Chapter Current service.