Replacing a radiator fan belt on older cars is a relatively straightforward procedure that doesn’t require any specialized mechanical knowledge. Under most circumstances it’s a job that won’t take a lot of time. On some cars, however, the belt isn’t readily accessible; if that’s the case, and you’re not an experienced mechanic, it’s better to leave it to someone who knows what he’s doing. Otherwise you can do it yourself.
When Do You Need to Replace a Belt - You should check all engine belts every time you pop the car hood, or at the very least, whenever you change your oil, which should ideally be every 3,000 miles. Test the belts for tension and inspect for any cracks or wear, especially uneven wear. If you spot any, then it’s time to change the belt. If you’re driving and the temperature gauge rises when you stop, but falls again when you start moving, it can be a problem with the belt. You also have a problem if the belt makes a high noise when moving. In both instances, replace it.
Preparing to Change the Belt - Unless you’re an experienced shade tree mechanic, you should either have the service manual for your vehicle or use a digital camera to take pictures of the way the belt is arranged over the pulleys to avoid any confusion later.
Removing the Belt - The belt will be stretched over pulleys. To remove it, you’ll need to loosen the tensioner on one of them. Be aware that this is very tightly sprung, so loosen it slowly with the wrench, following the direction indicated on the tensioner. Once it’s loose enough to slip the belt off the pulley, do that, and remove it from the other pulleys.
Finding a New Belt - Take the old belt to an auto parts store. Compare it with those on stock. Is it a V belt, or a serpentine belt (one with several grooves). Select a matching belt of about the same length, preferably slightly smaller, but most certainly not any longer. If you have any doubts, ask the clerks for advice; they’ll be happy to help you find the right belt for your car.
Fitting the Belt - With the tensioner loosened, slip the belt over the other pulleys then ease it over the pulley with the tensioner. With a V belt, make sure the V is fitted evenly on the pulleys. In the case of a serpentine belt, ensure the belt lines up properly on all the pulleys. Tighten the tensioner to the point it had been before. Don’t over tighten it. Try moving the belt manually. As a general rule of thumb, you should only be able to move it a little, about half a turn of the pulley, before feeling some resistance. At this point, start the car and inspect how the belt is running. Excessive noise can mean that the belt is too tight. Turn off the engine, then loosen the tensioner and slacken off the belt just slightly. If the belt is slipping a little, then turn the engine off and tighten the belt more. Keep checking until the belt is running evenly and smoothly.