Drive belts don't wait for a convenient time to fail. They also have been known to squeal as they start to give out. If you own a Chevy that was made after 1987, these are the instructions for replacing your S-belt. This should be done as part of normal maintenance every 35,000 miles or so as needed.
Before checking the drive belt make sure that the engine is off and cold. The drive belt is an S-Belt or serpentine belt in all S-10s after 1987. Under the hood, carefully inspect both sides of the belt and the edges using your hand and a flashlight. Look for excessive wear. Rubber coming off or building up on the pulleys, a shiny (glazed) belt, poor groove/ridge condition, missing pieces, aligned cracks, or deep cracks all indicate that replacement is needed. Check the tensioner to see if it indicates the belt is worn by looking at the position of the arrows.
Check the tension of the drive belt. Find the tensioner (see illustration). The easiest way to do this look at the tensioner to see if the arrow is aligned between the two V-shaped grooves at the base of the tensioner. If it is not, it may indicate that the belt has stretched. Find two pulleys that are less than a foot apart. Press on the belt. If the belt sinks more than 1/4 of an inch, the belt is not tight enough. Loose belts can cause a squealing noise and the glazed appearance mentioned earlier.
Look at the diagram that comes in your car (see photo). Make sure that you take note of the way the belt wraps around the pulleys, including the characteristic "S" shape, before removal. Also make sure to notice which way the belt faces on the pulleys. Find the bolt on the face of the tensioner and apply pressure with a wrench to loosen the tensioner from the belt. The diagram in your truck should indicate which way to rotate wrench on the tensioner bolt to loosen it for installation (see the curved arrow in the photo).
Remove the belt at this point by sliding it off one of the pulleys (assuming replacement is necessary). Make sure to note how the belt is wrapped through the engine before sliding the belt off of the other pulleys. Carefully and gently release the tensioner back into position. Do not remove the tensioner itself, as it is unnecessary.
Install the new belt by applying pressure to the tensioner as you did when you removed the previous belt. Put the new belt on according to the diagram on your engine compartment (see the photo example). Normally, this diagram is included in the engine compartment and should be assumed to be unique for your vehicle year. Slowly release the pressure on the tensioner. Double check the belt to make sure that it is sitting snugly in place all the way around. Adjusting the belt should not be necessary since the tensioner is designed to remove this necessity.
