Replacing the fan belt or serpentine belt on a Ford E-150 4.6L is a somewhat challenging yet rewarding job. The serpentine belt encompasses all of the major parts of the engine, from the alternator to the water pump. The process of changing the belt should take no longer than one hour, if you have never done this type of work before. All of the tools and materials needed for this job are available at an auto parts store.
Remove the plastic radiator fan shroud. This is the plastic hood that covers the radiator fan. Use a 3/8-inch drive ratchet to remove the shroud.
Press downward on the tensioner to release the belt tension, using a 3/8-inch drive ratchet in the allocated hole on the front of the tensioner.
Remove the belt completely from the engine, and slide it in front of the cooling fan to remove it from the engine compartment.
Loop the new belt around the cooling fan and back onto the engine pulleys. Use the "Belt Routing Diagram" located on top of the radiator to correctly align the new belt with the proper pulleys.
Release the tension in the tensioner to slide the serpentine belt into its final position. Let the tensioner return to its natural position.
Tap the ignition key into the starting position two times without actually starting the engine. This will let the engine pulleys spin and center align the belt on the pulleys automatically. Visually inspect the serpentine belt to ensure that it is not hanging off center of any pulleys.
Reinstall the radiator shroud.
