Positive Crankcase Ventilation Valve: Testing and Inspection

Crankcase Ventilation Valve Cross Section:

PCV System Service:

FUNCTIONAL CHECK OF CRANKCASE VENTILATION VALVE
If an engine is idling rough, check for a clogged crankcase ventilation valve or plugged hose. Check valve part number to he sure the correct crankcase ventilation valve is installed. Replace as required. Use the following procedure:

1. Remove valve from rocker arm 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 or manifold port, or valve. Replace plugged or deteriorated hoses.
4. Turn "OFF" the engine and remove valve. Shake valve and listen for the rattle of check needle inside the valve. If valve does not rattle, replace valve.

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 inlet duct and is drawn into the engine.

Proper operation of the crankcase ventilation system is dependent upon a sealed engine.

If oil sludging or dilution is noted, and the crankcase ventilation system is functioning properly, check engine for possible cause and correct to ensure that system will function as intended.