PCV System: Testing

To test crankcase ventilation system, start engine and allow it to reach normal operating temperature. Make sure engine is idling at normal curb idle, and perform following checks:

1. Remove PCV valve from its mounting. If valve is functioning properly, hissing noise will be heard as air passes through it. Strong vacuum should be felt when your finger is placed over valve inlet.
2. While finger is over inlet, check for presence of vacuum leaks in hose line and at all connections. Reinstall PCV valve, remove crankcase air inlet hose at air cleaner.
3. Loosely hold piece of stiff paper over opening at end of inlet hose. Paper should be sucked against hose opening with noticeable force after sufficient time has elapsed for crankcase pressure to lower (usually about a minute). For final check, stop engine, remove PCV valve and shake it. Metallic clicking noise should be heard, indicating valve is free.
4. If system passes both engine running and stopped tests, it is functioning properly. No further tests are required. If it has failed either test, replace appropriate components and retest. If it does not pass on second try, clean system.