Positive Crankcase Ventilation: Testing and Inspection

Crankcase Ventilation System Inspection/Diagnosis

1. Disconnect the PCV hose that connects between the cam cover and the air cleaner.
2. Start the engine.
3. Check for slight vacuum at the hose. If there is no vacuum, check for a plugged hose, intake manifold orifice or cylinder head port. Replace the plugged hose or clean the intake manifold orifice and cylinder head port.
4. Allow the engine to idle at normal operating temperature.
5. Remove the engine oil dipstick and install a vacuum gage on the dipstick tube.
6. Block off the PCV system hose that connects to the cam cover and air cleaner.
7. Run the engine at 1500 RPM for 30 seconds, then read the vacuum gage while engine is running at 1500 RPM.

* If vacuum is present, this indicates that the crankcase ventilation system is functioning properly.
* If no vacuum is indicated, the engine may not be sealed and is drawing in outside air. Check the cam covers, the oil pan gasket or other sealing areas for leaks.
* If the vacuum gage registers a pressure, or if a vacuum gage is pushed out of dipstick tube, check for a restricted PCV intake manifold orifice or cylinder head port, or an excessive engine blow-by.