Positive Crankcase Ventilation: Testing and Inspection

FUNCTIONAL CHECK OF CRANKCASE VENTILATION VALVE
If an engine is idling rough, check for a clogged crankcase ventilation valve. Replace as required. Use the following procedure.

1. Remove crankcase ventilation valve from intake manifold.
2. Shake valve and listen for the rattle of needle inside the valve. If valve does not rattle, replace valve. With this system, any blow-by in excess of the system capacity (from badly worn engine or sustained heavy loads) is exhausted into the intake manifold and is drawn into the engine.

Proper operation of the crankcase ventilation system is dependant 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 the system will function as intended.