The serpentine belt on a Ford Explorer Sport Trac keeps all of your drive accessories turning with the engine. This is how the air conditioning compressor, water pump, power steering pump and alternator are able to function, with just one belt turning them all. When this belt goes out or needs to be replaced, everything shuts down, so changing it is imperative if you want to drive the truck. In this case, the project vehicle is a 2004 Explorer Sport Trac, but the process is similar for other vehicles as well.
Pop the hood and locate the belt routing diagram. This is typically either on a sticker under the hood or on the core support. Make sure you know where this is before you start taking off the belt.
Locate the belt tensioner on the front of the engine, which is located on the passenger side. It has a square slot in the middle of it. Put the socket extension onto the breaker bar and place the extension into the square slot on the tensioner.
Pull up on the breaker bar to release the tension from the belt. When it goes limp, slide it off of the pulleys on the engine and discard. Release the tension on the tensioner.
Place the replacement belt around the crankshaft pulley at the very bottom middle of the engine, and start to route the belt according to the diagram you located in step 1. When the belt has no more play, pull up on the breaker bar and route the belt around the tensioner. Once the belt appears to be aligned correctly, release the breaker bar.
Visually inspect the belt to make sure it is squarely in each pulley and it doesn't appear to be out of alignment. Remove the breaker bar from the engine compartment and start the vehicle. Watch the belt and make sure it's running straight. If not, stop the engine and readjust.
