The harmonic balancer on your Mustang 5.0-liter engine serves three different purposes. It is used for setting the ignition timing for the engine, it provides the rotational force to turn the accessory drive belts and it helps to balance the crankshaft. The harmonic dampener can wear out over time, making replacement of this part necessary. With the right tools, you can do this in about an hour.
Remove the serpentine belt. Rotate the tensioner pulley upwards to relieve tension from the belt and remove the belt. Mark the outside edge of the belt with the chalk if you will reuse it. This will mark what side of the belt faces outward.
Remove the drive belt pulley assembly from the dampener by unfastening its four bolts. Set the bolts and pulley aside.
Loosen the harmonic dampener bolt in the crankshaft. Leave the bolt threaded at least three or four full turns. Attach the puller to the dampener, placing its foot against the head of the crankshaft bolt. Thread the pulley bolts as far into the dampener as they will go. Turn the center threaded shaft on the puller clockwise with a socket and ratchet until the dampener rests against the bottom of the retaining bolt head.
Remove the puller from the dampener. Grasp the dampener firmly and pull it off the crankshaft.
Slide the new dampener over the end of the crankshaft. Thread the bolt in as far as it will go by hand and torque it to between 85 and 100 foot-pounds. Reattach the pulley assembly.
Replace the serpentine belt, paying careful attention to belt routing. Rotate the tensioner counterclockwise and slide the belt over the final two pulleys.
