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Home >> Jeep >> 1990 >> Wagoneer >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 2.5L >> Positive Crankcase Ventilation (PCV) System >> System Test
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System Test

  1. Start engine and allow it to reach normal operating temperature. Ensure engine is at normal curb idle. Remove PCV valve from grommet. If valve is okay, hissing will be heard as air passes through it. Strong vacuum should be felt over inlet valve.
  2. With finger over valve inlet, check for vacuum leaks at all connections. Reinstall PCV valve and remove crankcase air inlet hose at air cleaner.
  3. Loosely hold piece of stiff paper over opening at end of inlet hose. After about a minute, paper should be sucked against hose opening with noticeable force. Remove and shake PCV valve. Ensure metallic clicking can be heard, indicating valve is free.
  4. If system passes both engine running and stopped tests, it is functioning properly. If it fails either test, replace defective components and retest. If it does not pass on second try, clean system.
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