Positive Crankcase Ventilation: Testing and Inspection

PCV System:

SYSTEM CHECK

If an engine is idling rough, check for a clogged positive crankcase ventilation (PCV) valve or plugged hose. Replace as required. Use the following procedure.

1. Remove PCV valve from the valve cover.
2. Run the engine at idle.
3. Place your thumb over end of valve to check for vacuum. If there is no vacuum at valve, check for plugged hoses, manifold port or PCV valve. Replace plugged or deteriorated hoses.
4. Turn the engine "OFF" and remove PCV valve. Shake valve and listen for the rattle of needle inside the valve.
5. If valve does not rattle, replace valve.

NOTE: With this system, any blow-by in excess of the system capacity (from a badly-worn engine, sustained heavy load, etc.) is exhausted into the air cleaner and is drawn into the engine. Proper operation of the PCV system is dependent upon a sealed engine. If oil slugging or dilution is noted, and the PCV system is functioning properly, check engine for possible cause and correct to ensure that system will function as intended.


PCV VALVE CHECK

1. Remove PCV valve from the valve cover.

PCV Valve Test:

2. Blow into the cylinder head side of the PCV valve. Make sure that air passes through easily.

PCV Valve Test:

3. Blow into the intake manifold side of the PCV valve. Make sure that air passes through with difficulty.
4. If valve does not operate as indicated above, replace the valve.