Replacing the Serpentine Belt

Once you’ve noticed that the belt is worn out, that we already described in a previous tutorial, change it right away. In this step by step tutorial, we will explain how to change the serpentine belt. Here is the procedure for changing the serpentine belt.

Location of the Serpentine Belt

The first thing to do, of course, is to locate the belt. The belt system on almost every engine is in an opposite 90-degree position to the engine. To put it simply: when you pop the hood, this is the only visible belt system. The other one, the timing belt, is hidden by a plastic cover so you can’t make a mistake.

In most modern cars there is one belt, that goes around all the car aggregates. However, in some older models and depending on the engine construction, there may be two separate belts. In this case, check both of them and it would be best to change both at the same time.

The Tools that You’ll Need to Replace the Serpentine Belt

• Set of wrenches that match the job
• Multipurpose screwdriver
• Short lever (for versions with mechanical tension-er)
• Belt tension tester (optional)

Preparing the New Belt

Prepare a new belt that has the same dimensions as the old one. You can find the dimension in the car manual or perhaps on the plate in the engine space. Most part-shops will be able to give you the proper belt when they know the engine or car type.

Before starting you should also know: the belt is held in place by a tension-er. There are a few types:

• a spring-driven tensioner (the strain is caused by a spring)
• a mechanical tensioner (you have to tension the belt with a lever)
• some cars have gas propelled tensioners but this is rare

How to Replace Serpentine Belt

1. Do the replacement when the engine is cold or else you’re at risk of burning yourself. Take the key out of the ignition, just in case.
2. Take the new belt and compare it to an old one. If it isn’t an exact match, don’t start the replacement. Rather go and replace it or else you’re only losing time.
3. Take the proper wrench and loosen the tensioner. In the case of a spring, tensioner loosens the screw in the middle. The tensioner is made to loosen the belt when you turn the screw. If it’s a mechanical one loosen the screw and push the alternator towards the engine thus loosening the belt.

1. Take the old belt off. If it’s a system with more pullies (i.e. your in danger of forgetting the pathway of the belt) don’t be shy to draw it on a piece of paper. Most cars have a drawing of the pathway in the engine space.
2. Put the new belt on the pulleys in the proper way.
3. In case of the spring tensioner, put the wrench in place, turn the wrench, loosen the pulley and set the belt in place. Release the wrench slowly, letting the tensioner strain the belt.
4. In the case of the mechanical tensioner, put the belt in place around all the pulleys and retract the alternator using your hand or better, a short lever. Make sure that the lever has a foothold in a place that won’t damage the engine.
5. Check that the belt is going around all the pulleys and that it’s “sitting” properly on every and each one.
6. Check the tension of the belt using a tension tester. If you don’t have one, you can check it with your hand. The belt should have no more than 1-1.5 cm of resistance when you push it on the longest distance between pulleys.
7. Remove all of your tools, check that you’ve tightened all the screws and start the engine. The belt should run smoothly, without any vibrations or squeaking noises.

Remember to check the tension of the belt after a few hundred miles. It’s normal for the belt to drag up a bit. The spring tensioner will tighten the belt on its own. In the case of the mechanical tensioner, tighten by losing the tensioner screw and tighten it with your hand or lever.

Our advice is to always have a spare belt in your car. This kind of replacement can usually be done even on the road. So, if you get into this kind of trouble, you’ll be able to help yourself.