How to Replace a PCV Valve on a Mercury Marquis

by Tara Kimball
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Justin Sullivan/Getty Images News/Getty Images

The positive crankcase ventilation (PCV) valve is designed to ensure the air flow in your engine remains in the proper direction. The PCV valve routes the dirty air back into the air cleaner to be filtered before allowing it to flow back through the vehicle’s engine. Dirty air will pass contaminants into the engine and could potentially damage the components. If your PCV valve has become worn or caked with dirt, replacing it will help ensure that your engine runs smooth and efficiently.

Step 1

Locate the PCV valve at the top of the motor. It will be located on the valve cover and is connected to a long rubber hose that runs to the air cleaner.

Step 2

Disconnect the hose running to the air cleaner from the PCV valve. The hose should pull straight off with little resistance. Check the condition of the hose and verify that it is not cracked or clogged with buildup. If the hose is damaged or full of debris, it should be replaced.

Step 3

Pull the PCV valve from the grommet on the valve cover. Pull straight up on the PCV valve while twisting it, if necessary, to encourage it to break free.

Step 4

Push the new PCV valve directly onto the grommet. Be sure the valve is fully seated and locked into position. Reattach the air cleaner hose to the open end of the PCV valve. The hose will just slide on the valve.

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