10 Symptoms of a Bad Serpentine Belt【Guide】

 Engines might be the main source of power for your car. But a lot more is required to keep the other accessories moving, and that is where belts come in. 

It’s a fact that not all cars have similar designs, however, you’ll find belts, pulleys, chains in each of them.

Not all cars will have a single belt to power all the accessories but most of them do. So, serpentine belt problems can cause many different issues which can cost a lot to fix.

To avoid that, I came up with an idea to write this guide about 10 Symptoms of a bad serpentine belt to help you avoid the hassle of wasting money.But before we start, do check out more of our maintenance guides on transmission repair and cost  & Why does my car shake when I accelerate? to keep your car in tip-top shape

What Exactly is a Serpentine Belt?

As I’ve talked about it briefly in the intro, it’s a single constantly moving belt that runs a lot of necessary accessories in your cars. So, before you look into the bad serpentine belt symptoms, getting to know a bit more about this important rubber belt cannot be of harm.

This constantly moving belt is usually connected to your alternator, power steering pump, AC compressor, and water pump with pullies, belt tensioners, etc. In some cars, the water pump will not be part of this cycle and will be connected with the timing chain or belt.

Now a serpentine belt failure can cause all these connected components to stop working or even fail, and it can be dangerous as well if you’re on the move.  That’s why a serpentine belt should be regularly checked especially after 50000 miles or 5 years of use. 

Catching the early serpentine belt symptoms or even replacing it periodically even without the symptoms can help you avoid a major catastrophe. For example, serpentine belt failure can cause your water pump to fail, leading to engine overheating, which can, in turn, lead to head gasket failure, and much more.

How Do You Know if Your Serpentine Belt is Going Bad?

Now that you have a faint idea about what exactly are these belts, and how do they work. Let’s get you into the 10 most common symptoms of a bad serpentine belt. Although remember, not every car will get similar serpentine belt problems symptoms. So, recognizing the exact symptom is the key.

Most of the bad serpentine symptoms can be caused by some other moving part as well, so getting it diagnosed by a professional is always recommended if you are not sure or you’re scratching your head finding the source. Anywho, let’s list some of the most common bad serpentine belt symptoms.

Weird Screeching or Squeaking Noises

Noises such as screeching or squeaking can definitely count as a bad serpentine belt sound, however, the source of the sound is not always because of the belt itself. There are pulleys attached to each and every component, and these pulleys have bearings inside them. A slipping belt, a failing bearing, or tensioners

To verify what is causing the noise, you need to have a closer look. But in most modern cars, your belts might be hidden beneath some plastic cosmetic beauty covers. So carefully check your owner’s manual to know the exact method of removing it, or call an expert.

Once you can see the belt itself, spray some water on of the pullies to check if the noise stops, if it does. Then it’s a bad serpentine belt sound, not pullies. Although it does not necessarily mean that the belt needs to be replaced, you can have a misaligned or loose belt as well or it can be a Symptom of Bad Belt Tensioner.

Loss of Power in Power Steering

Since the power steering is usually a part of the serpentine belt cycle, loose, misaligned, or a bad serpentine belt can cause loss of power in your power steering. So, if your power steering is stiffer or not working like it used to, it can be an indication of bad serpentine belt symptoms, a failing power steering pump, or pullies.


Battery Dies or Doesn’t Charge

Just like the power steering pump, the alternator is also connected with the serpentine belt, and you get a battery indicator on your dash or a dead battery. It can be one of those broken serpentine belt symptoms. So before you panic, and opt for an expensive alternator, do check your serpentine belt to know it’s still intact.

A broken serpentine belt will not only cause your battery to die, but it will also cause issues such as power steering failure, engine overheating, and dead Aircon. However, if it’s not the belt, you might a bad alternator, find out more about alternator from our related guide on Can A Car Run With Bad Alternator?


No Aircon, or a Badly functioning Air Conditioner

The most common early failing serpentine belt symptoms are low cooling or no cooling at all in the air conditioner of your car or the power steering failure.

A slipping bad serpentine belt will cause loss of power to power steering and air conditioner functioning. However, air conditioner performance issues can be caused by other issues such as failing compressors, low gas levels, etc.

But the first thing to check is the serpentine belt and pullies of the air conditioner compressor. If the bearing inside the pully is getting stiff or about to get stuck, it can cause premature wear to the belt itself. However, you will be able to hear some squeaking sounds.

Car Overheating (No Water Circulation)

If your car’s water pump is connected to a serpentine belt instead of a timing belt or chain, chances are a broken serpentine belt will overheat the engine and can provide instant symptoms.

Overheating can be caused by many other reasons, such as low coolant levels, a stuck thermostat, or a clogged radiator. But if it’s sudden, do have a look at your serpentine belt.

A good tip is to turn on the heat in your car to see if hot air comes out, if it doesn’t, you either have no water circulation in your cooling system or the coolant level is low.

Worn-out belt (Cracks or visible damage)

Since all the serpentine belts are made out of rubber, with regular wear and tear they can extend or get hard. When a rubber belt gets harder it can form cracks that can eventually lead to breaking.

However, the good news is, you can easily check if your belt is wearing out by a visual or feel inspection. If it’s easy for you, I recommend removing the belt and slightly bending it back to see if there are cracks. Please only do this if you cannot spot visible cracks.

Cracked serpentine belt symptoms are not always easy to find without a visual inspection. Because if you’re still wondering “what happens when a serpentine belt goes bad?” well a lot. However, more on that later.

Oil or coolant on Serpentine belt

Not one of those direct bad serpentine belt symptoms, however, still can be considered as a cause for failure. So, if you find oil or coolant on your serpentine belt during regular inspections, chances are that either your engine is leaking oil or the water pump is leaking coolant.

A wet serpentine belt will fail sooner rather than later, so getting the issue fixed before installing a new one. Otherwise, you might keep wondering that why does my serpentine belt keeps shredding or starts failing prematurely.


More Symptoms that you Might Notice

Wobbly belt

Another reason for many serpentine belt problems is a misaligned belt. To make sure that your belt is not misaligned, check all the pullies to see if your belt is riding straight on them. If pullies are riding straight but the belt is wobbling, chances are your belt is misaligned.

However, if the pullies are not riding straight, you do need to get it checked and fixed or replace it. If you’re getting a belt squeak, a wobbly belt can be the answer.

Bad Idler Pulley Bearing

Another reason for squeaking noise is when the bearings in your idler pullies start to go bad. These idlers’ pullies are used to route the belt properly around the engine. They don’t really put pressure on the belt, however, they do freely spin with the belt.

If the bearing starts going bad, your belt will have to work harder to spin that bearing and will cause squeaking noises. So, periodically replacing these bearing is always recommended.

Bad Tensioner Pulley bearing

A spring-loaded or hydraulic belt tensioners put enough tension on the belt to keep it working smoothly. However, if the belt starts wearing out and slips, the tensioners might not be able to provide perfect tension. Or if the bearing starts seizing up, the tensions will cause belt failure or you might even get a belt that will come off.

Symptoms of Bad Belt Tensioner

Some of the most common bad serpentine belt tensioner symptoms include the following

  1. You get grinding noises or even squeaking noises
  2. Belt wear is not even
  3. Snapped belt, which can cause the above-listed symptoms


If you didn’t know much about the function and importance of a serpentine belt, this guide was the best place to land at. While the importance of this cheap part is now obvious, it’s is often forgotten. So, catching early symptoms, performing periodic maintenance is always necessary.

You can avoid  10 Symptoms of a bad serpentine belt by taking all the precautionary measures as on as you come in contact with just the one or the time limit exceeds. Although wait! before you go, check our FAQ box at the end to get more of your questions answered regarding the serpentine belts. I hope that after reading this guide, you now know how to tell if the serpentine belt is bad?


How long is a serpentine belt supposed to last?

A serpentine belt is usually designed to last five years of 50,000 miles minimum. However, it depends on the conditions that your car is operating in and the quality of the belt as well. Some can last above 100,000 miles. But it’s always better to replace it at around 50,000.

How to know when to replace the serpentine belt?

Replace the serpentine belt at regular maintenance intervals of 50,000 miles or 5 years or if you face any of the above-listed symptoms.

What causes a serpentine belt to break?

There are many things that can cause a serpentine belt to break such as a stuck bearing or a cracked serpentine belt. If your belt is weak, and your pulley bearing starts failing, it can easily snap of your belt in half.

What happens to a car when the serpentine belt breaks?

When your car serpentine belt breaks, you’ll immediately lose functions to the essential accessories of your car such as power steering, Air conditioning, Water pump, and the alternator. The power steering issue will be the first one that you’ll notice. Moreover, you may also notice the air con, however, until the car overheats you might not notice the water pump overheating.  However, without the power steering, you’ll most probably come to a halt beforehand

What happens when a serpentine belt breaks while driving?

If a serpentine belt breaks while driving, it can be pretty dangerous especially considering it controls the power steering. If it breaks you can lose control of the car and it can lead to a catastrophe. Moreover, your car can instantly overheat and cause your head gasket to leak.

What does a bad serpentine belt sound like?

Most of the time, you’ll be able to notice squeaking noise. However, it’s not always the case, so visual inspection is always recommended. To diagnose the squeaking noise refer to this video below:


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