Positive Crankcase Ventilation Valve: Testing and Inspection

DIAGNOSIS AND TESTING - PCV SYSTEM

WARNING: apply parking brake and/or block wheels before performing any test or adjustment with the engine operating.

1. With engine idling, remove the hose from the PCV valve. If the valve is not plugged, a hissing noise will be heard as air passes through the valve. A strong vacuum should also be felt when a finger is placed over the valve inlet.
2. Install hose on PCV valve. Remove the make-up air hose from the air plenum at the rear of the engine. Hold a piece of stiff paper (parts tag) loosely over the end of the make-up air hose.
3. After allowing approximately one minute for crankcase pressure to reduce, the paper should draw up against the hose with noticeable force. If the engine does not draw the paper against the grommet after installing a new valve, replace the PCV valve hose.
4. Turn the engine off. Remove the PCV valve from intake manifold. The valve should rattle when shaken.
5. Replace the PCV valve and retest the system if it does not operate as described in the preceding tests. Do not attempt to clean the old PCV valve.