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Home › Mitsubishi › 2008 › Lancer Evolution MR › Repair and Diagnosis › Engine Performance › System › Emission Control - Lancer Evolution › Positive Crankcase Ventilation System › Positive Crankcase Ventilation (PCV) System Check

Positive Crankcase Ventilation (PCV) System Check

  1. Remove the ventilation hose from the positive crankcase ventilation (PCV) valve.
  2. Remove the PCV valve from the rocker cover.
  3. Reinstall the PCV valve at the ventilation hose.
  4. Start the engine and run at idle.
  5. Place a finger at the opening of the PCV valve and check that vacuum of the intake manifold is felt.
    NOTE: At this moment, the plunger in the PCV valve moves back and forth.
  6. If vacuum is not felt, clean the PCV valve or replace it.
  7. Apply a small amount of new engine oil to the O-ring on the PCV valve, and tighten to the specified torque.

    Standard value: 2.5 ± 0.4 N.m (22 in-lb) 

    Fig 1: Identifying Positive Crankcase Ventilation Valve
    G05375530Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.


  1. Remove the ventilation hose from the positive crankcase ventilation (PCV) valve.
  2. Remove the PCV valve from the rocker cover.
  3. Hold the PCV valve with the vacuum side down. Insert a thin rod, and using light pressure, depress the end of the PCV valve spring by 5 - 10 mm (0.2 - 0.3 inch). Release pressure on the rod to see if the PCV valve spring will lift the rod to its original position.
  4. If the rod returns quickly to its original position, the PCV valve is OK. If the stick does not return quickly, clean or replace the PCV valve.
  5. Apply a small amount of new engine oil to the O-ring on the PCV valve, and tighten to the specified torque.
    Fig 1: Checking Positive Crankcase Ventilation Valve
    G05375531Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

    Standard value: 2.5 ± 0.4 N.m (22 in-lb) 

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