Diagnostic Aids

Perform this test when instructed during QUICK TEST or if directed by other test procedures. Use this test to diagnose Positive Crankcase Ventilation (PCV) valve and related vacuum hoses.

1. Check PCV System
   
   Start engine and warm to normal operating temperature. Disconnect hose from PCV valve. Listen for hissing noise from PCV valve. Place a finger over valve, strong vacuum should be felt. If vacuum is strong, go to next step. If vacuum from valve is weak, replace PCV valve and recheck for vacuum.
2. Check System Hoses
   
   Remove all PCV system hoses. Check for evidence of excessive blow-by (oily sludge). Repair as necessary.