GM 25040760 PCV VALVE

To solve this problem, the positive crankcase ventilation (PCV) system circulates fresh air through the crankcase in order to pick up blow-by gases, which are then rerouted back to the engine through a carburetor. Vacuum hoses and a PCV valve, which regulate the flow of gases according to engine speed and manifold vacuum, are the main components of this system. Carbon and gunk that accumulate in the PCV valve and hoses over time may cause them to jam, hence regular scrutiny is needed to ensure they function properly. Poor idling or reduced idle speed may indicate a restricted or stopped flow in the system. To test for proper vacuum pull off the top plate of the air cleaner and remove the hose leading to the small PCV filter. While your engine is idling put your thumb slightly on towards the end of this hose. A feeling as if there is a slight pull or suction tells that air is being drawn through it. If any vacuum is felt there should be further checks since low or no vacuum will mean that blocking has taken place within this system. By shaking it you can check whether the PCV valve clicks; if it does not, it should be replaced because its check needle does not work properly anymore. When running at idle speed with valve removed, engine should result in a relatively strong vacuum pressure. If there's no or very little difference felt in terms of vacuum pressure either way it might indicate blocked vacuum hose or inlet fitting at engine manifold. Clearing out passages clogged at manifold or carburetor require thorough cleaning, while failure of pcv valve necessitates replacement thereof. When buying a new one for your engine just make sure that you don't get something else instead of genuine PCV valves.

The PCV valve can be found on the rocker cover because of its running tube to the carburetor. Ensure that you purchase a substitute for the vehicle, engine size, and model year. It has to be removed by pulling the valve with hose still intact through its rubber grommet from rocker arm cover and then remove PCV valve from the hose while noting its position and direction of installation. Before installing it you must compare your new PCV valve with old one to see if they are similar. Push it entirely until seated properly to the end of the hose. If there are imperfections on this grommet, it should be changed with a new one.

The PCV valve should be checked for vacuum at idle, and the system's hoses and connections should be inspected and replaced as needed.

During installation, ensure the valve is securely inserted and clamped properly, and inspect related components for wear before reassembling the air cleaner and connections.

The PCV valve should be replaced every 30,000 miles (48,000 km).

The hose connected to the PCV valve runs to either the carburetor or the intake manifold.

Compare the old valve with the new one to confirm they are identical.

The PCV valve is located on a rocker arm cover.