Mercury Villager 2000-2002

Crankcase Ventilation System


Description & Operation

Filtered air from the air cleaner-to-intake manifold hose is drawn into the crankcase through breather hoses connected to the rocker arm covers. Intake manifold vacuum, applied through the PCV valve to a breather hose connected to the right rocker arm cover, draws crankcase vapors into the intake manifold.

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Fig. Crankcase ventilation system flow

Removal & Installation

For the PCV valve replacement procedure, please refer to General Information and Maintenance, Routine Maintenance and Tune-Up, PCV Valve, Removal and Installation.


  1. Check the PCV breather hoses for wear, damage, or obstruction.
  3. With the engine running, remove the PCV vent hose from the valve. There should be a loud hissing noise as air is drawn through the valve.
  5. Place a finger over the end of the valve. Strong vacuum should be felt. If not, replace the valve.

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    Fig. Check the PCV valve for vacuum at idle