Inspect the belts for signs of glazing or cracking. A glazed belt will be perfectly smooth from slippage, while a good belt will have a slight texture of fabric visible. Cracks will usually start at the inner edge of the belt and run outward. All worn or damaged drive belts should be replaced immediately. It is best to replace all drive belts at one time, as a preventive maintenance measure, during this service operation.
CHECKING TENSION & ADJUSTING
Inspect your car's drive belts every 7,500 miles or six months. Replace the belts at a maximum of 30,000 miles, even if they still look acceptable.
You can determine belt tension at a point halfway between the pulleys by pressing on the belt with moderate thumb pressure. The amount of deflection should be in proportion to the length of the belt between pulleys (measured from the center of each pulley). For example, a belt stretched 13-16 in. between pulleys should deflect 1 / 2 in. at the halfway point; a belt stretched 7-10 in. should deflect 1 / 4 in., etc. If the deflection is found to be too little or too tight, an adjustment must be made.
Before adjusting any of your engine's drive belts, clean all mounting bolts on the component being adjusted and apply penetrating oil if necessary on those bolts which are hard to reach-which may be many if your car has a V8 with lots of power options. Loosen the mounting and adjusting bolts of whichever component (alternator, air pump, air conditioner compressor, power steering pump, etc.) you are adjusting. Pull outward, away from the engine, on the component until the belt seems tight. Temporarily snug up on the adjusting bolt and check belt deflection; if it is OK, tighten the mounting bolts and adjusting bolt.
Avoid using a metal prybar when adjusting belt tension of any component; a sawed-off broom handle or large wooden dowel rod works fine. Excessive force on any of the component housings (which are usually aluminum) will damage the housings.
REMOVAL & INSTALLATION
- Loosen the drive accessory's pivot and mounting bolts.
- Move the accessory toward the engine until enough slack is created to remove the belt from the pulley.
- Place the new belt over the pulley and move the accessory away from the engine until the tension is correct. You can use a wooden hammer handle, or broomstick, as a lever, but do not use anything metallic, such as a prybar.
It is better to have belts too loose than too tight, because overtight belts will lead to bearing failure, particularly in the water pump and alternator. However, loose belts place an extremely high impact load on the driven component due to the whipping action of the belt.
- Tighten the bolts and recheck the tension. If new belts have been installed, run the engine for a few minutes, then recheck and readjust as necessary.