The serpentine belts on the Audi A4 are necessary to drive all of the accessory parts inside of the engine. Without a serpentine belt it would be impossible to run any of the electronics or the air conditioner inside of your Audi, but more importantly the engine would overheat after any extended operation. The Audi engine uses a tensioner bolt on a tensioner pulley to keep the belt taut and running properly. This bolt will make changing your belt a much easier operation.
Loosen the bolt on the tension pulley using a belt tensioner.
Pull the belt off of the alternator, water pump, tension pulley and any other devices it is attached to using your hands.
Inspect the new belt to make sure there are no breaks or cracks on either side of it.
Place the new belt over all of the pulleys that you removed the old belt from. Double check to make sure that the raised parts of the belt are properly seated in all the grooves of the pulleys.
Tighten the bolt on the tension pulley using the belt tensioner.
