The drive belt on a Ford F150 pickup truck runs multiple components of the engine, including the power steering pump, alternator, and water pump. The belt's tensioner is self-adjusting and never needs to be adjusted. If the tensioner won't keeping the timing belt properly tense, the tensioner must be changed out. The engine will not run if the drive belt is loose and won't properly turn all its pulleys.
Study the path of the drive belt and make sure you know exactly how it is routed. There should be a schematic of the belt's routing path printed on the cooling fan shroud.
Rotate the belt tensioner with a wrench on the tensioner arm to relieve the tension, slip the belt off of its pulleys and then slowly release the tensioner. Rotate the tensioner counter-clockwise if the truck has a V6 engine and clockwise on a V8 engine.
Unbolt the tensioner with the wrench and remove it from the engine. On a V6 engine, the tensioner has one bolt in the center. On a V8 engine, there are three bolts on the tensioner.
Install the replacement tensioner and bolt it in place.
Turn the new tensioner to release its tension again and install the drive belt, routing the belt across the pulleys in the correct path and making sure the belt is properly centered on the pulleys with the ribs fitting in the grooves. Slowly release the tensioner onto the belt.
