8 Symptoms of a Bad Serpentine Belt (And Replacement Cost)

That squealing under the hood when you start your car in the morning is no harmless noise. It’s an audible clue that your serpentine belt needs attention. This vital belt powers vital accessories like the alternator, AC compressor, and power steering pump by linking them to the crankshaft’s rotation.

When this drive belt starts glazing, cracking, or slipping, the result can be a variety of issues. Heeding the signs of a bad serpentine belt right away can help you avoid being stranded with a disabled vehicle and an expensive repair bill down the road.

What is a Serpentine Belt?

serpentine belt replacement cost

A serpentine belt, also called a drive belt, fan belt, or accessory belt, is the main engine belt that you see when you open up the hood of your car. These belts are easily identifiable by their distinct ridges that run the length of the belt on one side. The ridges help maintain grip when turning the accessory pulleys.

Serpentine belts are different than timing belts, which are usually not visible just by popping the hood. You usually have to tear down part of the engine to reach the timing belt.

Engine accessories need to get their power from somewhere, and it may surprise you to learn that that place is not the battery. As your engine runs, the spinning motion of the crankshaft is transferred to each of the accessory pulleys via the serpentine belt.

If your vehicle is supercharged, the serpentine belt also powers the supercharger.

Serpentine Belt vs V-Belt

Older engines have v-belts instead of serpentine belts. These are thinner and smaller than serpentine belts and usually connect one accessory to the crankshaft. You’ll often see multiple v-belts in an engine, but only one serpentine belt. Both types of belts serve a similar purpose. 

Common Bad Serpentine Belt Symptoms

A bad serpentine belt is not the type of maintenance you want to defer. A snapped serpentine belt could leave you stranded. If the alternator pulley stops spinning, there’s no way to charge the battery.

Several signs will present themselves when a serpentine belt is starting to wear out. Below are some of the most common symptoms of a worn serpentine belt.

1) No Air Conditioning

air conditioning

A malfunctioning air conditioner can be attributed to a lot of things. Since the serpentine belt keeps the air conditioner functional, a bad serpentine belt will take that function away from it.

If you turn on your air conditioner and see that it does not blow out cool air from the air vents, this could possibly be due to a bad serpentine belt.

2) Squealing Sounds

noise while driving

If the front area of your vehicle makes squealing sounds, then your serpentine belt might be misaligned or slipping. Sometimes it might just take a realignment or proper tensioning of your serpentine belt to fix this problem.

In other cases, the belt is probably damaged and will need to be replaced.

See Also: Common Causes of Serpentine Belt Noise

3) No Power Steering

no power steering

The serpentine belt allows the power steering system to function properly. Power steering is what gives drivers the ability to smoothly steer their vehicle without needing to apply too much arm strength.

If you have a bad serpentine belt, then it will be harder to move the steering wheel to steer your vehicle.

This issue could also be caused by low power steering fluid. While you’re under the hood, check to make sure the power steering reservoir has the recommended level of fluid.

4) Flapping or Scraping Sound

drive belt slippage

If your serpentine belt is loose or frayed, you may hear a rhythmic flapping or scraping sound in the engine bay. This sound is often correlated to each revolution of the engine. As you give the car gas to raise the engine speed, this rhythmic sound should speed up. Sometimes it gets louder, too.  

Sometimes a loose serpentine belt can be fixed by adjusting or replacing the serpentine belt tensioner. In some cases, you will need a new serpentine belt.

5) Visible Cracks on Belt

cracks in serpentine belt

The serpentine belt is easy to access in most cars. If you want to know if your belt is bad, simply open the hood and look at the belt for yourself. If you notice visible cracks or damage to anywhere on the belt, this means the belt is bad and needs to be replaced right away.

6) Dead Battery

car battery light on

If you’re driving along one day and suddenly lose power, check under the hood to see if your serpentine belt is still attached. Even if you’re able to get the car started, a snapped serpentine belt will not allow the alternator to charge the battery.

Without the alternator’s charge, your car will eventually die from the electricity used by the spark plugs, the radio, and the headlights. A vehicle can often run without a working alternator for a bit of time, but not for long. 

If the belt is too loose to maintain grip on the alternator pulley, you may experience a similar symptom as a snapped belt.

7) Pulley Whine

noisy belt pulley

If you start to notice a whine from the engine that changes with engine speed, you may want to have the tension of the serpentine belt double checked. A belt that is too tight puts too much load on the bearings in each of the accessory pulleys and can often cause premature failure of those components.

One of the most common failure modes for engine accessories is actually bearing failure, caused by a serpentine belt that was too tight. If you think your belt may be too tight, it’s best to address this issue as soon as possible to prevent expensive engine damage to peripheral components.

8) Engine Overheating

prevent engine overheating

For engines where the serpentine belt is driving the water pump, this is going to be the most important symptom. If the serpentine belt becomes damaged or worn out, it can slip or break, which can cause the water pump to stop functioning properly.

When the water pump isn’t working, coolant is not circulated through the engine, and the engine can quickly overheat. Overheating can cause damage to engine components, such as the cylinder head, head gasket, and engine block, which can be expensive to repair or replace.

Serpentine Belt Replacement Cost

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It is very inexpensive to replace a serpentine belt, fan belt, AC belt, or power steering belt whether it’s broken or loose. The replacement cost of a drive belt is only going to be between $100 and $200 in most cases. The belt itself will cost between $30 and $90 while the labor costs will probably be between $150 and $200. 

The ease of accessing the serpentine belt will determine how much the labor costs are. Some model vehicles have the serpentine belt easily accessible, which means the labor should take under one hour. But if the belt is in a more complicated area, it could take about 2 hours.

Easy to reach belts can actually be changed at home with minimal tools. Some belts can be removed by loosening one bolt, while others have a belt tensioner you have to pull on with a wrench to give the belt some slack. You might consult a repair manual for your specific vehicle to see if you can do this yourself.

Either way, this is certainly one of the cheaper components of an engine that you will ever have to replace. It is better you replace this immediately than risk more expensive components getting damaged.

Proper Maintenance

Regularly inspect your serpentine belt for any signs of wear or damage, such as cracks, abrasions, or separation. This will help you identify issues early and avoid any unexpected breakdowns or costly repairs.

To keep your serpentine belt in good shape, you’ll also want to regularly check its tension. A loose or improperly adjusted belt can lead to slippage and premature wear, while a belt that’s too tight can cause strain on the engine’s components.

It’s also a good idea to periodically clean your serpentine belt, as grime and oil can contribute to wear and tear over time and cause noise. To clean your serpentine belt:

  1. With the engine off, spray some engine degreaser on the belt and the pulleys driving it.
  2. Allow the degreaser to sit on the belt for a couple minutes.
  3. Completely rinse off the degreaser using a garden hose being careful not to spray water on sensitive parts of the engine. You may even rinse the belt off with the engine running and then allow it to run until fully dry.

Frequently Asked Questions

What Happens When a Serpentine Belt Breaks While Driving?

If your serpentine belt breaks while driving, the first thing you’ll notice is a sudden loss of power steering, making it harder to turn the wheel. Your air conditioning may stop working, and the engine might start to overheat because the water pump is no longer circulating coolant.

The alternator could also stop charging the battery, potentially causing warning lights to appear on your dashboard. It’s important to pull over and shut off your engine immediately if you suspect a broken serpentine belt, to prevent further damage.

Can Serpentine Belt Issues Affect Acceleration?

Yes, serpentine belt issues can affect acceleration. A worn or damaged belt may slip along the pulley system due to inadequate tension, creating a screeching sound when starting the engine or accelerating hard.

This slipping can cause a decrease in power provided to various systems in your vehicle, such as the power steering, alternator, and air conditioning. This loss of power can result in reduced performance and hinder your car’s acceleration ability.

How Long Do Serpentine Belts Last?

The typical lifespan of a serpentine belt varies depending on the make and model of your vehicle, as well as the type of belt used. On average, you can expect a standard serpentine belt to last about 60,000 to 100,000 miles.

It’s a good idea to consult your vehicle’s owner’s manual for the manufacturer’s recommended service intervals when it comes to drive belts.

How Much is a Serpentine Belt?

A serpentine belt will cost somewhere in the range of $30 to $90 in most cases. If you’re changing it out yourself, this is all it will cost but if you’re paying for someone else to replace it, expect another $150-$200 in labor costs. 

How Does a Bad Belt Tensioner Impact the Serpentine Belt?

A bad belt tensioner can have a major impact on the serpentine belt since its job is to maintain proper tension on the belt. If the tensioner is damaged or worn, it may not be able to keep the proper tension, potentially causing the belt to slip, wear out prematurely, or even break.


35 thoughts on “8 Symptoms of a Bad Serpentine Belt (And Replacement Cost)”

  1. My SUBARU IS 6 years old & has only 22,000 miles on it. Does the belts need changing. Don’t see or hear any problems. All is working well

  2. I have a 2004 infinity g35 coupe which has the serpentine belt squeals and then after a while of it squealing one day I was at a stop light waiting for it to turn green and when it did I pressed on my gas pedal to go through the light and all I got was a little bit of power I’d say 10% of the normal power then I put it into neutral and it would regain normal power then I put it back into drive and again the same thing happened so then I turned off my headlights and while it was in drive it would be fine all the while the belt was still squealing so I limp it home after putting it into neutral and back into drive a couple of times doing that it slowly regained power and when I got home which was from the start of when it started acting up to my house was about a mile and a half. So when I got home and put it into park and shut it off I tried to turn it over and the battery was completely dead. So I was wondering if it’s the altanator? or the serpentine belt? Thank you and have a great day.

    • Start with the serpentine belt. If the belt is squealing, that means it is slipping. If the belt is slipping, it probably isn’t spinning the alternator pulley, allowing the battery to charge properly.

      Inspect the serpentine belt for any cracks or broken ribs. If you find any, replace it. Serpentine belts are pretty cheap and you may be able to do the work yourself. Just take a picture of the belt arrangement on the pulleys (or look up a diagram) and make sure you put the new belt back on the same way. Make sure you set the belt tension correctly. Some vehicles have automatic tensioners. Others you adjust by tightening a bolt a certain amount.

  3. Made 160,000 miles with my serpentine belt before it I could hear a faint squealing sound running the AC at idle. $30 for a new belt and about a 10 min job to replace it in a 2009 Jeep Wrangler.

  4. Dear Friend
    My car has a belt with nearly 30k miles. it has some cracks but when I showed to mechanic he said it is ok and you don’t need to replace it. the cracks are not like those you’ve showed in pics but it does have some minor crack. do you think I have to replace it

    thank in advance for reading my question

  5. 2002 Honda Civic
    Loud squeal on cold start..drive a bit and it comes again.

    New alternator
    New front brakes
    Power steering fluid full
    No steering problems
    A/C works good
    Heat works good
    What could be the problem?

    • The serpentine belt is probably too loose. When you replaced the alternator, did you check the belt tension?

      While you’re in there, check the serpentine belt for cracks or other damage, particularly on the ribbed side of the belt. Replace if necessary.

  6. I have 3 of the quoted issues. Whining noise, battery light, and air conditioner not blowing strong cool sir. Honda Accord 2010. Is that a good thing? Considering it could be worse?

  7. My air kind of works but my car feel like power is lost in the first couple gears.is sounds like it’s over reving.i just got a new battery and alternator.it ran for acouple months then the battery light came on.then the car went into battery saving mode and the car just like shut off.i have a 2011 charger

  8. Hey! I was driving when I started to head a “whooshing” sound (air) under the car. A little later, I realized that when I accelerated, there was a loud clunking sound that significatnyl increase when I hit the gas. It only happens with the AC on. Upon inspection, we found a tear in the intake hose and replaced that but the sounds still occur. You can only hear the sound from inside the car (my buddies didnt hear anything when standing outside the car). I have a 2003 Honda CR-V. Any ideas on what it would be?

    • You might have some loose parts in your cooling system. Check the blowers (fans) and mounting components. The easiest way to do this is to turn the AC on max and try to listen for the source of the clunking. You might hear the sounds in the engine bay, so check under the hood as well in case the problem is located there. If you do find some loose bolts, apply some thread locker to them to prevent the problem from recurring.

  9. Replaced my belt literally about 3-4 weeks ago. Brand new. Just got in car saw battery light on so checked the belt and sure enough was broke again. There is black or oil maybe I think and after car runs awhile starts smoking from the belt area and if you are sitting still and run the air it smokes from that area and if you have air pulling from the outside to inside you bring all the smoke in the vehicle. Can run it from inside circulating while driving no problems but sitting still it does that and doesn’t work well. Even if don’t run the air at all after you’ve driven for awhile and pull off or come to a stop for a minute you will see smoke from that area coming out. My assumption is the oil or black stuff all on that side is getting hot and burning and that’s the smoke issue because it runs fine but could this be the cause my belt broke after 3-4 weeks of replacing?

    • It’s quite possible. Smoking like that isn’t normal. Figure out what is causing the smoke, fix that, and replace the belt again. When you replace the belt, make sure the tension is set correctly. Some cars have automatic tensioners, others require you to set it yourself.

  10. My car was in an accident. The a/c hasn’t worked right sense. They got it blowing cool and it only gets cool after the car has been running or if in a cool spot. When car is hot it won’t run. Now it wont cool at all. Any ideas what it could be?

  11. Is the A/C screeching for sure this problem? It still blows cold air but just started squealing and making a lot of noise in the passenger dash area.

  12. I get a price of 1950.00$ for replacing the belt and the bolt that broke and is inside the car belly somewhere (Bmw. Z4 3.0) I was told that radiator has to be removed and AC Ac has to be recharged . Is this honest price?


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