How do you change a serpentine belt on a 2000 e-250?

To change the serpentine belt on a 2000 E-250, first, locate the belt tensioner and use a wrench or ratchet to relieve tension on the belt. Remove the old belt from the pulleys, noting the belt routing for installation of the new one. Place the new belt according to the routing diagram (often found on a sticker under the hood) and then use the wrench to adjust the tensioner again to fit the belt. Finally, double-check the alignment and ensure the belt is properly seated on all pulleys before starting the engine.