Positive Crankcase Ventilation Valve: Testing and Inspection

PCV Valve:

PCV Location:

1. With engine idling, remove hose from PCV valve. If valve is not plugged, a hissing sound will be heard as air passes through the valve, and a strong vacuum should be felt when a finger is placed over the inlet of the valve.
2. Reinstall the PCV valve hose, then remove the make up air hose. With engine idling, loosely hold a piece of stiff paper (such as a parts tag) over the opening in the hose. After allowing about a minute for the crankcase pressure to reduce, the paper should be drawn against the opening in the rocker arm cover.
3. With engine off, remove PCV valve from the intake manifold and shake the valve. A rattling noise should be heard, indicating that the valve is free.
4. If the system passes the above tests, no further service is required. If not, replace the PCV valve and recheck the system. Do not attempt to clean the PCV valve.
5. With a new PCV valve installed, if the paper is not drawn against the make up air hose opening with considerable force, it may be necessary to replace the make up air hose.