LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> GMC >> 1974 >> Magnavan >> Repair and Diagnosis (Single Page) >> Engine Mechanical >> Auxiliary Emission Control Systems >> Crankcase Ventilation Systems >> System Checking >> Testing PCV Valve
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Testing PCV Valve

  1. Connect tachometer and vacuum gauge to engine, set parking brake, start engine and adjust idle speed and mixture.
  2. Disconnect ventilation hose at PCV valve, block opening of valve and read engine RPM change.
  3. A change of less than 50 RPM indicates a plugged PCV valve.
scientia non olet · About LEMON Manuals