Positive Crankcase Ventilation: Testing and Inspection

Crankcase Ventilation System Inspection/Diagnosis

1. Remove the oil level indicator. Install a vacuum gage.
2. Start the engine.
3. Check for slight vacuum. The vacuum level should be less than 3.377 kPa (1 in Hg).
4. Block or pinch off the clean air hose. The clean air hose is the hose between the cam cover and air cleaner.
5. Vacuum should show on the gage. If held too long, vacuum will be drawn through the crankshaft seals creating a sucking sound.
6. If there is zero vacuum or pressure:
1. Verify compression of the engine.
2. If compression is normal, check for a blocked orifice at the intake manifold clean orifice.
7. If there is vacuum and a constant sucking sound around the seals, inspect the fresh air hose for a blockage.