How to Install a Serpentine Belt on a 3.8 Mustang

by Thomas West

The 3.8 liter V-6 engine was used in Ford Mustangs from 1983 to 2004. The 3.8 liter engine provided an intermediate option for those who wished to have more power than the standard four-cylinder engine but with no need for all the power of the available V-8. After 1993, the four-cylinder engine was dropped from the Mustang line and the 3.8 liter V-6 became the new standard Mustang engine. The serpentine belt on your 3.8 liter Mustang drives the alternator, air conditioner, power steering, and the water pump. Keeping your belt in good condition and replacing it when needed will insure you will not be stranded by a broken belt in the future.

Step 1

Open the hood. Locate the serpentine belt-routing sticker affixed to the radiator cross-member ahead of the engine fan. Make a note of how your belt is routed if your sticker is missing. Play close attention to whether the front (smooth) or the back (ribbed) side of the belt rides on each pulley in the engine bay, as this will quicken the installation of the new belt.

Step 2

Locate the serpentine-belt tensioner at the top of the engine, which has a black pulley run by the serpentine belt and is mounted to a cast-aluminum base.

Step 3

Insert the drive end of a 1/2-inch ratchet wrench or breaker bar into the square hole on the cast-aluminum base of the belt tensioner.

Step 4

Rotate the wrench or breaker bar handle in a counterclockwise direction to release the belt tension. Be careful, as the tensioner is under great spring pressure.

Step 5

Slip the belt off the idler pulley, which is at the top-center of the engine. Slowly let the spring tension raise the ratchet or breaker-bar handle. Do not let go of the handle quickly, as it will snap back. Remove the ratchet or breaker bar once the tension has been released.

Step 6

Slip the belt off the remaining pulleys and work it up and out of the engine bay.

Step 7

Slip a new belt over all of the pulleys by using the belt-routing sticker or the notes you made earlier. Leave the belt off the idler pulley at the top of the engine.

Step 8

Release the belt tension by inserting the ratchet or breaker bar into the tensioner and rotating the handle counterclockwise. Slip the belt over the idler pulley while holding the handle down. Release the handle slowly until the belt is under tension. Remove the ratchet or breaker bar and close the hood.

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