How to Adjust Drive Belts

Modern vehicles rely heavily on the use of the drive belt. The drive belt powers the alternator, air condition, power steering, and in some cases, the water pump. Proper operation of the drive belt is important in maintenance of the vehicle.

As the drive belt ages, the stress from powering items such as the power steering pump and the alternator can cause the belt to stretch. When the belt stretches, it can begin to slip, if left unattended.

Not all types of drive belt systems can be adjusted. Cars equipped with an automatic belt tensioner adjust themselves over time and do not require adjustment.

This article shows you the process to adjust drive belts on a pivot-style belt adjuster.

  • Warning: Drive belts that are cracked or excessively worn should be replaced. Only belts that are in good working order should be adjusted. To check the condition of your drive belt Signs Your Drive Belt is Worn.

Part 1 of 3: Check the drive belt tension

Materials required

Step 1: Locate the tension point. First, you need to locate the longest stretch of belt so that you get the most accurate results while checking the drive belt tension.

drive belt center point

Using a measuring tape or a ruler, find the center point on the longest stretch of the drive belt.

drive belt tension being checked with a ruler

Step 2: Check the belt tension. Now that you have found the center point on the belt to measure, you can check the belt’s tension.

Depress the belt with your finger and measure how much the belt is able to move. Most manufactures recommend between ½ inch and 1 inch of movement.

  • Tip: Check the owner's manual for exact specifications for your vehicle.

Alternatively, you can check belt tension by twisting the belt; if it twists more than halfway over, the belt is too loose.

Part 2 of 3: Adjust the drive belt tension

both pivot point and drive belt adjustment bolt

Step 1: Loosen the adjustment points. The first step is to locate the drive belt pivot point bolt. This is usually found opposite the adjustment bolt mounted on the the alternator. The pivot bolt will be loosened just a bit. Do not remove the bolt all the way

Next, find the adjustment lock bolt and the adjuster bolt. Loosen the belt adjustment bolt.

driver belt adjustment screw pointed and shown turning

Step 2: Adjust the drive belt tension. With both the drive belt pivot bolt and adjuster lock bolt loose, slowly tighten the adjustment bolt to achieve the desired tightness.

  • Note: Tightening the adjustment bolt makes the belt tighter and loosening the bolt will make the belt looser.

Tighten the bolt at the amount of belt tension you want keeping in mind that the belt will get a little tighter when you lock everything down. If the alternator has trouble moving, use a flat head screwdriver to lift up gently on the alternator.

  • Note: Take care to not break any parts of the alternator and do not pry off any plastic parts.

Part 3 of 3: Check the drive belt tension again and secure the alternator

Step 1: Tighten all the bolts. The first step is to tighten the drive belt adjuster lock. The bolt should be tight, but take care not to overtorque it.

Next, tighten the pivot point bolt. This will tighten the belt a bit more too.

Now that everything is tight, check your work any make sure that everything is secure.

Step 2: Check the belt tension. With everything tight, check the belt tension using a measuring tape or a ruler. The belt should not twist more than half of the way over and should have the recommended amount of depression.

Finally, start the engine and make sure the belt does not squeal or make any unusual noises.

Adjusting your car’s drive belt is a part of vehicle maintenance during regular service intervals. Having a properly adjusted belt not only helps the belt last longer but also eliminates and squeaky noises that may have been present before.

If at any point you are uncomfortable about performing this maintenance yourself or if you feel the drive belt needs to be replaced, contact the qualified technicians at YourMechanic for help.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How to Replace Your Serpentine Belt
If If your engine squeals in the morning when you first start it up, take a look at your serpentine belt (https://www.yourmechanic.com/article/how-long-does-a-serpentine-drive-belt-last) under the hood. Any cracks, glazed areas, or visible threads mean that you need to replace it (https://www.yourmechanic.com/services/serpentine-drive-belt-replacement)....
How to Check Belts in Your Car
Engine drive belts are a crucial part of how your car functions. Knowing how to identify any issues with them can help prevent a breakdown.
How to Quiet a Noisy Drive Belt
The drive belt operates different accessories mounted on the engine. The best way to minimize it's noise is to adjust the drive belt to specification.

Related questions

Drive belts make high-pitched chirping sound
Firstly, I would recommend replacing your serpentine belt (https://www.yourmechanic.com/services/serpentine-drive-belt-replacement) as it is a regular maintenance item on all vehicles with internal combustion engines that use a belt. The reason for the noise is that over time after the belt has...
Serpentine belt came off so I need the diagram so I can put it back on
Here is a good diagram of your serpentine belt. (http://i.fixya.net/uploads/images/9cfdc9e.jpg) If your belt came off on its own then you most likely have a bad belt tensioner and need to replace it.
How much money should it cost to replace a drive belt
You may have problems with the tensioner for the belt and not just the belt. Also the power steering should not stop when turning on the a/c. You should first have a mechanic inspect the belt and tensioner along with...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com