There are many types of automotive belts with different functions. Some of these automotive belts include AC belts, fan drive belts, distributor drive belt and the serpentine belt. The serpentine, or S belt, is a very commonly-used belt system in a car, because of its simplicity and efficiency. This S-belt system is found underneath your car; it is composed of a long, sturdy belt that connects to other different belts, which in turn connect to different automotive functions. Some of these peripheral belts include the belt alternator, air pump, power steering pump, fan drive belt and timing belt (in cars with overhead cams). These individual belts are weaker and smaller than the serpentine belt, and would therefore require more frequent replacement.
How would you know that one of your automotive belts needs replacement? One symptom you could look out for would be noisy, squealing sounds that busted automotive belts commonly make. Also, take note of how long your automotive belts have been in operation, as they typically need replacement after every set interval: for example, the S belt (or serpentine belt) would generally need to be replaced after every 4 years, or 30,000 to 60,000 miles. Make sure that you find out the actual specifications on replacement as indicated in the user's manual. Another way of knowing if your automotive belt needs to be replaced is by simply inspecting it. Apart from the noise that has been mentioned above (which could be the first obvious sign), other signs include the following: cuts or cracks on the belt, missing chunks, or a shiny appearance.
Serpentine belt repair and belt replacement is considered to be much easier to do than repairing or installing the smaller, individual belts. This is because it usually just entails loosening the specific pulley belt, which secures the S belt. After having loosened this pulley belt, the S belt would loosen as well, and then you could replace it with your new one.
A word of caution, however: Many belt tensioners are very tight, and it's recommended that you use a tool specifically designed for their removal. Most car engines are designed so that you can easily remove the S belt after having loosened the belt tensioner, but in some designs, you have to remove other parts and engine components, which are mounted over the S belt.
To help you better understand how to go about the replacement of any automotive belt in your car, make sure that you secure a belt diagram and manufacturer's instructions on how to remove and replace particular belts from your car engine. It also helps for you to make your own diagram of the belt's routing before you take it apart - remember, sometimes it's much easier to take it apart than to put it back again.
Once you've put in the appropriate replacement belt, make sure that you secure each and every bolt very, very tightly. To check if you've replaced the belt properly, get in the car and turn on the engine; watch out for squealing or grinding sounds.
Of course, it's always a good investment to have your belts inspected by a certified mechanic, especially if you're not too sure of your own mechanic skills. Good luck!