Positive Crankcase Ventilation: Testing and Inspection

Crankcase Ventilation System Inspection/Diagnosis

1. Disconnect the positive crankcase ventilation (PCV) hose.
2. Start the engine.
3. Check for vacuum at the PCV hose. If there is no vacuum, inspect for a plugged hose or manifold port. Inspect for a hose that collapses when blocked with vacuum applied. Replace the plugged or the deteriorated hoses.
4. Allow the engine to idle at normal operating temperature.
5. Remove the engine oil level indicator. Install a vacuum gage into the indicator tube opening.
6. Block off the PCV system fresh air intake passage.
7. Run the engine at 1,500 RPM for 30 seconds, then read the vacuum gage while engine is running at 1,500 RPM.
^ If vacuum is present, 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 valve covers, the oil pan gasket, or other sealing areas for leaks.
^ If the vacuum gage registers a pressure, or if the vacuum gage is pushed out of indicator tube, check for a plugged PCV port, a plugged hose, or excessive engine blow-by.