The 5.3 Vortec V-8 engine is standard on the larger GMC trucks. The front engine accessories on the Vortec engine are operated by a single multi-ribbed serpentine belt. The single belt is designed to fit around all of the accessory pulleys at one time. When the engine is running, the belt tensioner maintains the proper tension inside each accessory pulley. Over time, the belt tensioner will wear out and not be able to apply the proper tension on the belt. When this happens, you need to replace the tensioner immediately.
Raise the hood and inspect the front of the engine for the belt tensioner. The belt tensioner on the 5.3 Vortec engine is located on the lower left side of the engine beside the crankshaft pulley. Use the square opening on the front of the tensioner to loosen the tension from the belt.
Lower the breaker bar into the engine well and slide the end of the breaker bar into the square opening of the belt tensioner. Pull the breaker bar counterclockwise to loosen the tension from the belt. Slide the belt off the tensioner pulley and let it hang down.
Loosen the two mounting bolts on both sides of the belt tensioner, using a ratchet and a metric socket.
Pull the belt tensioner straight off the front of the engine block and out of the engine well. Position the new tensioner onto the same area and screw the two mounting bolts into the new tensioner bracket. Tighten the mounting bolts with the ratchet and socket.
Turn the tensioner counterclockwise with the breaker bar to get the belt back around the tensioner pulley. Slide the belt onto the pulley and slowly release the breaker bar. Remove the breaker bar from the tensioner and the engine well. Make sure that the belt is still inside of each accessory pulley.
Crank the engine and watch the new belt tensioner as the belt is traveling under the tensioner pulley. The tensioner should be moving freely with the movement of the belt with no restrictions. Turn the engine off.
