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.
Toyota measures belt tension in pounds of force as determined by a belt tension tester. The Nippondenso and Burroughs testers are available through dealers or may be found at retail auto parts stores. The tester slips over a short section of the drive belt, and, when tightened, reads the deflection pressure on a dial. This is one of the most exact ways of setting tension and purchase of this tool or its equivalent is recommended.
Specifications for new belts are slightly higher than for used belts. A new belt is one which has not been run under tension for more than 5 minutes. Anything else is a used belt.
REMOVAL & INSTALLATION
When buying replacement belts, remember that the fit is critical according to the length of the belt ("diameter"), the width of the belt, the depth of the belt and the angle or profile of the V shape. The belt shape should exactly match the shape of the pulley; belts that are not an exact match can cause noise, slippage and premature failure.
If a belt must be replaced, the driven unit must be loosened and moved to its extreme loosest position, generally by moving it toward the center of the motor. After removing the old belt, check the pulleys for dirt or build-up material which could affect belt contact. Carefully install the new belt, remembering that it is new and unused-it may appear to be just a little too small to fit over the pulley flanges.
Fit the belt over the largest pulley (usually the crankshaft pulley at the bottom center of the motor) first, then work on the smaller one(s). Gentle pressure in the direction of rotation is helpful. Some belts run around a third or idler pulley, which acts as an additional pivot in the belt's path. It may be possible to loosen the idler pulley as well as the main component, making your job much easier. Depending on which belt(s) you are changing, it may be necessary to loosen or remove other interfering belts to get at the one(s) you want.
After the new belt is installed, draw tension on it by moving the driven unit away from the motor and tighten its mounting bolts. This is sometimes a three or four-handed job; you may find an assistant helpful. Make sure that all the bolts you loosened get re-tightened and that any other loosened belts also have the correct tension. A new belt can be expected to stretch a bit after installation so be prepared to re-adjust your new belt, if needed, within the first hundred miles/kilometers of use.