Positive Crankcase Ventilation Valve: Testing and Inspection

Crankcase Ventilation Flow:

Crankcase Ventilation Valve Location:

Results of Incorrect Operation:
A plugged valve may cause:
^ Rough idle
^ Stalling or slow idle speed
^ Oil leaks
^ Sludge in engine

A leaking valve would cause:
^ Rough idle
^ Stalling
^ High idle speed

Functional Check:
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, sustained heavy load, etc.) is exhausted into the intake manifold 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.