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How to Replace the Serpentine Belt on My Mercury Marquis

by Don Bowman

There are four different serpentine belt routings for the 4.6-liter engine in a Mercury Marquis. The belt-routing diagram is depicted on a placard on the radiator support shield, which is on the top of the radiator cover just to the left of the hood hinge. It is also in the owner's manual. In the event neither is available, draw a diagram of the routing prior to removing the belt, which is a fairly simple job that requires only a few tools.

Loosen the tensioner with the ratchet and the appropriate socket to fit the bolt in the center of the tensioner pulley. Install the ratchet and socket on the bolt and pull the tensioner away from the belt. When the tension is removed from the belt, lift the belt off the alternator.

Look at the belt-routing diagram for reference to facilitate installation. The belt has a smooth top and grooved bottom. The grooved side of the belt always passes over the grooved pulleys, with the grooves intermeshed. The smooth pulleys always have the top smooth side of the belt contacting them. The water pump, idler pulley and the tensioner are the only ones with a smooth surface. The belt is installed counterclockwise, starting on the crankshaft pulley and moving to the water pump. The belt will only go on one way, so it won't fit if it's installed wrong.

Install the belt over the crankshaft pulley. Hold the belt with your left hand to keep a small amount of tension on it so the belt does not fall off as you are installing it. With your right hand, grab the belt at the top of the crankshaft pulley and pass it over the top of the water pump pulley, which is directly above the crank pulley. The smooth top of the belt should contact the water pump. Continue down the right side and place the grooved side on the power steering pulley.

Pull the belt up, with the smooth side contacting the idler pulley. Pass the belt over the top alternator pulley, with the grooves contacting the pulley. Continue down to the idler, with smooth side contacting the pulley. Move the belt down so that the grooved side contacts the air conditioning compressor. You should have a little slack in the belt.

Pull the belt toward the tensioner on the left side. The belt will be too short to go over the pulley until you install the ratchet and pull the tensioner away from the belt. Place the belt under the tensioner, with the smooth side toward tensioner. Allow the tensioner to operate and apply tension to the belt.

Items you will need

About the Author

Don Bowman has been writing for various websites and several online magazines since 2008. He has owned an auto service facility since 1982 and has over 45 years of technical experience as a master ASE tech. Bowman has a business degree from Pennsylvania State University and was an officer in the U.S. Army (aircraft maintenance officer, pilot, six Air Medal awards, two tours Vietnam).

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