Why Do the Belts in My Car Squeal?

Screeching, squealing, squeaking—whatever you call it, the belts in your car can make a horrible, fingernails-on-the-chalkboard kind of noise. Whether it happens right when you start your car or while accelerating, this noise can really stress you out.

What causes your belts to make that terrible squeal and what can be done about it? Let’s take a look at the possibilities.

What Do Engine Belts Do?

The engine belt in your car is also referred to as the drive belt or fan belt. Most cars today only have one of these belts, but some have multiple.

The purpose of the engine belt is to transfer power from the engine to other components of the car, such as the fan, alternator, water pump, and air conditioner. If this belt breaks or gets too loose, then those components won’t have power anymore. Eventually that would lead to things like your car overheating, your battery dying, etc.

So if there’s a problem with your engine belt, you want to get it fixed before it leads to further damage.

Possible Causes of the Squeal

Essentially, the squealing noise happens when the belt isn’t staying in even contact with the metal pulleys that move it. It’s like the noise made by rubber-soled shoes squeaking across a hard floor.

There are several different reasons why that slipping or scuffing could be happening. First, the engine belt might not be at the right tension. If it’s loose, then it will slip and cause that awful screeching noise.

To keep the belt at the right tension, the car has a device called an auto belt tensioner. The tensioner can get misaligned, or the spring-loaded arm or ball bearing in the tensioner can simply wear out. Either way, this can lead to a loose belt.

On the other hand, the engine belt could be at the wrong tension due to improper installation. When a new belt is put in, the tension should be set, then engine should be run for a few minutes. Then the tension must be adjusted again.

If that readjustment isn’t performed, your new belt could start squealing again after a short time of driving the car. If you just recently had the belt replaced and now it’s squealing, improper installation could be the problem.

Aside from tension problems, another possible cause for a squealing belt is an accessory or component that’s going bad. If one of the components connected to the belt has problems, it can cause excessive drag on the belt, leading to a squeal.

Likewise, if one of the pulleys is loose or misaligned, that can lead to squealing too. Or if you have a fluid or oil leak, the moisture on the belt could be causing it to slip and squeal.

Finally, one of the most common causes of belt squealing is simply wear and tear. Belts wear out over time, becoming loose, rough, or brittle.

It’s important to note that usually when the engine belt wears out, that means that the timing belt is wearing out as well, so mechanics often recommend that you replace both at the same time to avoid the major damage that can be caused if your timing belt breaks.

Overall, if you have a squealing belt in your car, the safest and fastest approach to dealing with it is to take your car in for service ASAP. There are a lot of possible causes for a squealing belt, and if it’s not taken care of quickly, it can lead to much more serious problems than an annoying noise.