Positive Crankcase Ventilation: Testing and Inspection

PCV SYSTEM FUNCTIONAL CHECK
1. Check PCV valve for correct application
2. Engine at normal operating temperature
3. Block off PCV system fresh air intake passage
4. Remove engine oil dipstick and install a vacuum gage on dipstick tube
5. Run engine at 1500 rpm for 30 seconds then read vacuum gage while at 1500 rpm. If vacuum is present the PCV system is functioning properly. No vacuum indicated the engine may not be sealed and/or is drawing in outside air. Check valve cover, oil pan gasket for leaks. If the vacuum gage registers a pressure or the vacuum gage is pushed out of the dipstick tube, check for the correct PCV valve, a plugged hose or excessive engine blow-by.

EXCESSIVE BLOWBY
With this system, any blow-by in excess of system capacity is exhausted into the intake manifold and is drawn into the engine. Proper operation of the PCV system is dependent upon a sealed engine. If oil sludging 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.