If your air compressor is running noisily or if it is vibrating a lot, its belt may need to be tightened. In some cases, inefficient pressure at the point of use or a receiver that is building up pressure slowly, may also be signs that the belt needs help. Luckily, it's pretty easy to tighten the belt on your own.

Here's what you need to do:

1. Remove the Belt Guard  

Turn off all the power to the air compressor, and remove the air guard. These are usually held on with screws, and once you remove the screws, you can lift off the belt guard easily. If you cannot see any screws, you may need to check your compressor's owner's manual for instructions.

2. Check the Belt for Damage

Before tightening the belt, you need to look it over for damage. If it is frayed, ripped, or hanging extremely loosely, you may want to replace it. You can order belts online or through an air compressor company in your area.

3. Loosen the Motor

To tighten the belt, you are essentially going to move the motor. This increases the distance over which the belt is hung, and that effectively tightens the belt. In most cases, the motor is held to the deck with four bolts, two on each side.

These bolts typically descend into slots on the air compressor's deck. Before you start, use a permanent marker to mark the spot where the bolts are. You may need this mark for reference when you move the motor.

Use a wrench to loosen the bolts, and note that you may need to grip the nuts under the deck for extra support. You don't have to take out the bolts. Instead, just loosen them enough so that they can slide around in the slots. This allows you to move the motor.

4. Move Motor With Belt Attached

Once the bolts are loosened, you can opt to continue with the belt attached. This approach is best if you have two people. Keep in mind, even a loose belt on an air compressor has a lot of tension, and that makes it hard to move the motor.

One of you should grab the deck of the air compressor on the side opposite the motor. Take a firm stance so you can really stabilize the compressor for the other person. The other person in turn needs to pull the motor away from the flywheel and pulley. In most cases, you don't need to move the motor very far. When the belt looks tight, one of you should hold the motor in place as the other one tightens the screws.

If you don't have anyone to help you, you can attempt this method on your own. Grab a sturdy plank, and wedge the plank behind the motor assembly. Gently push on the plank and use the leverage to help you move the motor forward. Again, you don't need to move the motor very far. Then, tighten the bolts and remove the plank.

5. Remove Belt

To remove the belt, just roll it off the pulley assembly on the air compressor's motor. When it is gone, the motor will move easily. Use the markings as guides so you don't forget the original spot. Then, move the motor slightly, and prepare to put the belt back on.

To replace the belt, push it into the top of the sheave and carefully rotate the assembly around until the belt snaps into spot. This is very similar to the process of replacing a chain on a bicycle.

Finally, when the belt has been tightened, replace the belt guard, and begin to use the air compressor as usual. If you have other issues or you want help tightening your belt, contact an air compressor specialist.