Replacing Fan Belts: Car Repair and Maintenance

Tips for Fixing a Serpentine Belt and More

The name "fan belt" is a bit of a misnomer nowadays because the belt drives much more than just a fan. It is frequently called an accessory belt. The fan belt goes around a pulley attached to the flywheel and powers accessory pumps and motors such as the water pump, air conditioner compressor, alternator, power brakes, and the power steering pump. Some cars have one large serpentine belt that drives all of the accessory motors. Other cars divide the work more evenly by employing the use of two belts. So as you can see, fan belts are important items and should be on your car maintenance list of items to check from time to time.

Regardless of whether your car uses one or two belts, you can change your fan belt with some time and a few simple tools that you already have around the house. Here's how to replace your fan belt:

  1. Routine inspection: You should inspect the belts every time you look under the hood to practice good auto maintenance. Look for cracks and frayed sections. If any part of the interior of the belt is cracked, or if any part of the cording in the belt is frayed, then you will need to replace it.
  2. Fan Belt Diagram: Your car has a diagram describing the path of the belt on your particular car. Before you take the belt off, check the diagram under the hood. It is usually on the plastic cover above the cooling fan. Follow the diagram exactly when removing the old belt and when installing the new one. The diagram also displays where a special pulley, called the belt tensioner is located. You can adjust the tensioner to change how tight the belt is as it goes around the pulleys.
  3. Take off the old fan belt: Take the old belt offCar engine of the pulleys. You will need a wrench or two to release the tension on the belt. Tension systems differ between makes, but the effect of each is still the same: They maintain a tight belt when in use, and they allow you to adjust the tension. In this case, you want to reduce the tension on the belt so that you can slide it off of the pulleys.
  4. Get the right size replacement belt: You'll need to get the right size replacement belt at any local auto parts store. It's very important to match the new shape with the old one. Take the old belt with you to the store to compare with the new belt. Sometimes the new one is a little bit different length. If it is a centimeter or so short, then that is OK. It will likely stretch out a little bit. If it is a little too long, ask the salesperson to help you find a closer match. A longer belt isn't acceptable.
  5. Install the new belt: When replacing fan belts, route the new belt through the pulleys so that it uses the exact same path as the old belt. You may need to loosen the tensioner a little bit more in order to slip the new belt onto the final pulley. Refer to the diagram to check your work. After it is in place, tighten it using the tension adjuster on your car.
  6. Helpful fan belt repair tips: The belt should be taut, and should not squeal when the engine is running. To determine if it is tight enough, remove anything that could get caught in moving parts and turn on the engine. Turn on the air conditioner. If the belt doesn't squeal, then it is probably tight enough.

    When you tighten the belt, be careful not to get it too tight. If it is too tight it will put too much stress on all of the pulleys in the system and will cause one to fail over time.

    Sometimes the belt will begin to squeal a few days after installation. This is because it will sometimes stretch a little. Simply tighten it a little at a time at the tension adjuster. This should help get rid of the squeal.

Now you know one of the most important aspects of car repair: replacing fan belts.


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