Chevrolet 25043669 Valve, Crankcase Vent (Pcv)

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To remove and install the PCV valve, pull the valve and hose straight out of the valve cover or manifold. Use pliers to slide the hose clamp, if equipped, down the hose and off the valve connector. Twist the valve gently to loosen it from the hose and remove it. Inspect the hose and valve cover grommet, and replace them if they are hard, brittle, or cracked. Clean the hose with solvent if it is clogged. Install the valve into the hose, ensuring it seats fully. Attach the hose clamp, if equipped, around the valve assembly. Finally, install the PCV valve in the grommet, making sure it seats fully in the cover grommet.

The positive crankcase ventilation (PCV) system reduces hydrocarbon emissions by circulating fresh air through the crankcase to pick up blow-by gases, which are then re-routed through the carburetor to be reburned by the engine. The main components of this system are vacuum hoses and a PCV valve, which regulates the flow of gases according to engine speed and manifold vacuum. The PCV system should be checked regularly for proper operation, as carbon and gunk can clog the PCV valve and hoses over time. Symptoms of reduced or stopped flow in the system include rough idling or a reduced engine speed at idle. To check for proper vacuum, remove the top plate of the air cleaner and disconnect the hose leading to the small PCV filter. With the engine idling, place your thumb lightly over the end of the hose. You should feel a slight pull or vacuum, indicating that air is being drawn through the system. If there is very little or no vacuum, the system is clogged and further inspection is required. The PCV valve can be checked by shaking it and listening for a clicking sound, indicating the valve's check needle is functioning properly. If the valve does not click freely, it should be replaced. Running the engine at idle speed with the PCV valve removed should result in a relatively strong vacuum. If little or no vacuum is felt, the vacuum hose or inlet fitting at the engine may be blocked. A clogged passage at the carburetor or manifold requires thorough cleaning, while a failure of the PCV valve necessitates replacement. When purchasing a new PCV valve, ensure it is the proper one to avoid causing damage to the engine.

The PCV valve is located on a rocker arm cover.

To replace the PCV valve, first, pull the valve (with the hose attached) from the rubber grommet in the rocker arm cover or manifold. Then, loosen the retaining clamp and remove the PCV valve from the end of the hose, taking note of its installed position and direction. Compare the old valve with the new one to ensure that they are the same. Push the new valve into the end of the hose until it is properly seated, and then reinstall the clamp. Inspect the rubber grommet for any damage and replace it with a new one if necessary. Finally, securely push the PCV valve and hose into position.

The PCV valve is typically located in one of the rocker arm covers on the side of the engine.

Locate the PCV valve in the valve cover or intake manifold behind the throttle body on 3.4L engines. While the engine is idling at normal operating temperature, remove the valve from its rubber grommet. Cover the valve's end with your finger and check for vacuum. If there's no vacuum, inspect for blockages in the hose, manifold port, or the valve itself. Replace any obstructed or deteriorated hoses. Turn off the engine, shake the PCV valve, and listen for a rattle. If there's no rattle, replace it.

Inspect the rubber grommet at the rocker arm cover for damage and replace it with a new one if needed.