How to Adjust the Tension on a Serpentine Belt in a Chevy 4.3 Engineby Christian Killian
The 4.3-liter V6 engine has been use in many Chevy cars and trucks since the late 80's. The engine features a serpentine belt system that drives the various accessories attached to it; while adjustment is supposed to be automatic on this belt system, the tensioner can sometimes hang up and fail to adjust as the belt wears and stretches. This does not always mean that you have to replace the tensioner, although sometimes it may be the only way to fix the problem.
Disconnect the negative battery cable from the terminal on the battery. Remove the clamp bolt from the cable end, pull the cable off the terminal and set it aside. Isolate the battery cable from the battery terminals while you are working around the belt.
Locate the serpentine belt on the front of the engine, place a socket on the center of the tensioner's idler bolt, then attach a breaker bar to the socket.
Rotate the tensioner counter-clockwise, releasing the tension from the belt. Slowly rotate the tensioner clockwise, allowing it to tighten the belt. Check the belt to see if it has more tension in it or not. Often, the spring inside the tensioner will stick and the tensioner will need to be "reset" to properly adjust.
Repeat the process several times, checking the belt after each adjustment. The tensioner should take the slack out of the belt, but if it does not, the tensioner is faulty and replacement is the only fix. If the adjustment works, reconnect the negative battery terminal to the battery and tighten the retaining bolt with a wrench. If the adjustment does not work, remove the tensioner and replace it.