How to Adjust Belt Tension

The drive belt is used to facilitate the movement of various parts of an engine, viz., A/C compressor, power steering, air pump, etc. This belt is guided using a belt tensioner. This belt tensioner needs to be adjusted to control the movement. The serpentine belts used now a days, do not require any belt tension adjustment, as these have in-built automated belt tensioner which adjusts the tension of the belt. However, most of the vehicles have the belt tensioners, and the tension has to be adjusted. You should thus know what kind of belt is installed in your vehicle’s engine, and also know how to adjust belt tension.

Here is a list of instruments needed in adjusting the belt tension.

  • Pry bar
  • Rocket and Ratchet Set
  • Set of Hand Wrench
  • Car lift
  • Impact Gun
  • Socket Set

How to adjust belt tension?

  • Lift the hood of the car and look for the drive belt. The procedure for adjusting the belt tension varies with different vehicles. The belt tensioner and drive belt may also be placed in a different pattern in different vehicles.
  • Some vehicles, for example would need the removal of the front tire to access the drive belt. To find out the exact placement and fitting of your drive belt, check your user manual.
  • Check whether there are individual tensioners for the belt and find out how you can access it. For some, you would need to raise the vehicle and remove the tire, with the help of car lift, impact gun, etc.
  • In the standard procedure, you will have to loosen the alternator bracket bolts and the bolt that retains the bracket as well. Loosening these bolts will let the alternator move back and forth with the slot of the bracket.
  • Cocking in the alternator, will help you to reduce or relax the tension on the belt. To increase the tension on the belt, pry the alternator and the opposite pulleys against each other, and tighten it. This increases the tension on the drive belt.
  • Next step is working on the adjuster. It is usually located on or near the alternator and has adjuster bolts on it. This is a very standard set up for most of the vehicles.
  • Firstly, loosen one adjuster bolt by turning it counter clockwise. Next step is to loosen the pulley, such that it wobbles enough, and the belt can be removed.
  • Place it back properly and tighten the adjuster bolt at the place where you feel the tension is correct. Turning the bolt in clockwise direction will get the desired tension on the belt.
  • After adjusting you need to check the belt tension. To check this there is a standard procedure.
  • If you can twist the belt by ½ turn using your finger and hand, as well as feel its resistance, it means the belt is adjusted correctly. If the belt can be turned more than ½ turn, then the amount of tension on the belt is less. If you cannot turn the belt even by ½ turn, then the belt has too much of tension.
  • Less tension on the belt will lead to early wearing of the belt, due to slipping of the belt. It will affect the functioning of the belt due to the belt slipping.
  • Belts that are high on tension or over tightened, will damage the bearing of the pulleys, overheat the belt, and damage it.
  • Replace all the components you detached, to access the belt. Test the vehicle by turning it on for some time and then turn it off. Again check the belt tension.


Checking the belt tension is very essential, because it will affect the final functioning of the vehicle. Do not directly go for a drive without checking the proper placement of parts, bolts and belt tension.


Refer to the user manual of your vehicle to understand about the belt adjuster. If this is your first experience, you can take help from some one who has been doing this for quiet some time now.

Proper belt tension will let you experience a smooth drive.

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  3. How to Replace Serpentine Belt
  4. How to Adjust Caliper Brakes
  5. How to Adjust Drum Brakes

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