GM 12691880 Valve Assembly, Pcv

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The Positive Crankcase Ventilation (PCV) system reduces hydrocarbon emissions by scavenging crankcase vapors and burning them along with the air-fuel mixture. It utilizes a PCV orifice for 6.0L models or a PCV valve for non-6.0L models, which are threaded into either the rear of the left valve cover for 4.3L V6 or below the throttle body in the intake manifold for 5.3L and 6.2L V8 engines. The system includes two hoses: the fresh air inlet hose carries outside air from the air intake duct to a pipe on the right valve cover, mixing with blow-by gases and crankcase vapors in the crankcase. These vapors are drawn through the orifice or valve, then into the intake manifold to mix with incoming air. For replacement, note that the procedure does not apply to 6.0L VB models, as the orifice is part of the driver's-side valve cover and is not serviceable separately; if clogged, the valve cover must be removed for cleaning. For 4.3L V6 models, the driver's-side engine cover should be removed, and for 5.3L and 6.2L V8 engines, the intake air duct must be taken off. Disconnect the hose from the PCV valve and use a socket to unscrew the valve from the engine, then reverse the removal procedures for installation.

To replace the valve, detach the hose from it and remove the valve from either the valve cover or the valve lifter oil manifold.