Learn how to change a belt in your car to save money on a professional mechanic. Your car has 2 or more belts, including a timing belt and a fan belt. The fan or accessory belt drives the fan and goes around a pulley attached to the harmonic balancer, powering accessory pumps and motors, such as the water pump and air conditioner compressor. Some cars have just one fan belt (a serpentine) while other cars use 2 belts. Changing your fan belt requires some time and a few tools that you already have around your house.
Tension of the Belt
When you replace the belt, you need to find the appropriate tension used. There are 2 types of systems found in cars.
The first is called constantly-tensioned (also known as a serpentine-belt). To configure the tension for this type, push the tensioner away from the belt using a wrench or a serpentine belt tool. Then pop the belt off from any point that is easy to reach. Replace the belt. Then push the tensioner away from the belt again. Finish the routing of the new belt (review a diagram if necessary)
The second system is called component-tensioned. This belt is tensioned by moving a component (such as the alternator) or a tensioning pulley.You will move either of these closer or farther away from the belt, thereby creating tension.
On either system, when replacing a belt, you must loosen the tensioning device. Remove the old belt and pay attention to the routing.
Replace the Belt
Hold the new belt against the old belt. Pull both belts tense at the same time using your thumbs. Stretch the belts out as far as they can go (their limit).
Install the new belt. Make sure the new belt is installed with the same route as the old belt. Once installed, compress the tensioner and place the last un-routed bit of the belt onto the pulley. Release the tensioner.
Tension the belt (if using a component or threaded adjuster). A properly tensioned belt needs to have at least ½ inch of movement in the middle of the belts longest run.
Double check if your belt(s) are straight. Make sure there are no twists or bends.
Making sure your tools are away from the engine compartment, turn over the vehicle (start it) and watch the belt. Check for problems. If your changed belt is squealing, grinding or smoking something is wrong. Turn the vehicle off, allow it to cool and check your installation by reviewing these steps.