What Causes a Serpentine Belt To Break? (Replacement Cost)

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What causes a serpentine belt to break? Aging, oil leaks, faulty components, and wear are the most common causes of a broken serpentine belt. Depending on the material used in making the serpentine belt; some belts last up to 50,000 miles, while some have a lifespan of up to 100,000 miles.

Practically, every component in a car would fail after a long time. That is why you need to keep up with maintenance and servicing to keep every component in good shape, all the time.

The serpentine belt connects various pulleys and components in the engine bay. It is a very crucial important that shouldn’t be ignored. A bad serpentine belt can cause the engine to malfunction, or not to work at all.

In this article, we will look at why serpentine belt breaks, the various symptoms of a bad serpentine belt, and the average serpentine belt replacement cost.

What Causes a Serpentine Belt To Break?

Nothing gets spoilt without being acted upon by an external, or natural force. Hereunder are the factors and conditions that can cause serpentine belts to break.

1. A Faulty Component

The serpentine belt connects quite many pulleys and peripherals, which include the alternator, water pump, power steering pump, air conditioning compressor, air pump, and many others. Now, if one of these peripherals breaks down, it’d exert more stress on the belt, which can cause it to break.

To break it down further, a failed bearing in the alternator can cause the serpentine to suffer more stress, and eventually break down when the exerted pressure becomes too much. That’s what we mean by saying that a faulty component can cause the serpentine belt to break.

2. The Belt is Already Weak

Serpentine belts are ever-rotating, non-stop. The moment you start your car, the belt starts rotating and it’d continue in that motion until you stop the car. Hence, serpentine belts have rated lifespans, which are based on the material used in making the belt.

Older serpentine belts were made of Neoprene rubber and they typically last for about 50,000 miles. Newer ones are made from Ethylene Propylene Diene Monomer (EPDM) rubber, and they are rated to last up to 100,000 miles or more.

So, if you’ve driven over 100,000 miles, it’s likely the serpentine belt in your engine would break anytime soon – get it replaced as soon as you can.

3. Oil Leaks

Sometimes you can’t tell how it happened, but you’d just notice that oil is leaking in your engine bay. If this is allowed to linger, and the serpentine belt gets soaked with oil, it causes the belt not to perform its functions as expected and could cause it to break in the long run.

It doesn’t matter if you just installed a new serpentine belt, if your engine is leaking oil, and it’s getting absorbed by the belt, in no distant time, you’d be replacing the belt again. That said, you have to find the source of the oil leak, get it fixed, and then install a new serpentine belt.

4. Faulty Hydraulic Belt Tensioner

Most cars of today include a hydraulic serpentine belt tensioner, which is sustained by a little “shock absorber.” If the belt tensioner or the shock absorber goes bad, it can cause the serpentine belt to break due to additional stress and workload.

It is important to fix the tensioner before installing a new belt, or the belt would get damaged quite sooner than you expect.

5. Misaligned Pulleys

Peradventure the last mechanic that worked on your car’s engine didn’t align the pulleys very well, which can cause to belt to squeal and break. Misalignment can also cause the belt to wear out faster and break down before the expected lifespan.

Actually, it’d be difficult for you to detect misaligned pulleys, you have to take the car back to a mechanic to perform the check. Signs that show the pulleys are misaligned include increased wear on one side of the belt and unusual loud whining noise while driving.

When To Replace the Serpentine Belt?

If you know the lifespan of the serpentine belt used in your car, once you hit the number of miles, you should have it replaced. Notwithstanding, there are scenarios where you have to replace the belt quite earlier than intended.

For example, if the belt is wearing out fast and making a hell of noise while you’re driving, you’d definitely want to change it as soon as possible.

Also, when you start getting the signs that your engine’s serpentine belt is about to fail, you should replace it immediately to avoid more expensive repairs.

Serpentine Belt Replacement Cost

What Causes a Serpentine Belt To Break

The cost of replacing serpentine belts is not really high!

The most expensive serpentine belt in the market cost below $80. However, the labor cost to replace and fix a bad serpentine belt can get up to $150 depending on the mechanic and other factors that may apply. So, the total average a bad serpentine belt replacement cost is between $150 – $250.

What are the Signs of a Bad Serpentine Belt?

A bad or broken serpentine belt can trigger any of these signs. The signs/symptoms may differ on different cars due to the difference in the engine’s peripheral configurations and arrangements.

Frequently Asked Questions

How Long Does a Serpentine Belt Last?

They are all built with rubber, but the rubber material differs in quality. Serpentine belts last between 50,000 – 100,000 miles depending on the type of rubber material used. If you’re not a frequent driver (drive less than 15,000 miles in a calendar year), you could use a serpentine belt for over 4 years, and it’d still be in good condition.

What Happens To a Car When The Serpentine Belt Breaks?

If you’re driven when it broke, you’d most likely notice a sudden loss of power, then your car starts being difficult to drive; steering would be hard, the AC would stop working, and your engine may gradually come to a stop.

This happens because the serpentine belt connects too many important components that make the engine perform the way it does. So when it breaks down, all these components are likely to stop functioning at the instance.

Can You Drive a Car With a Broken Serpentine Belt?

The simple answer is NO. You cannot drive with a bad or broken serpentine. This is because the belt pushes a lot of engine peripherals to function; if these peripherals are not triggered, the engine won’t work, and the car won’t start/drive. If you insist to drive with a bad serpentine belt, you may just wreck your engine.

Does The Serpentine Belt Affect The Transmission?

While the serpentine belt connects quite many important components that make a car drive, it is not connected to the transmission. However, the effects and anomalies caused by a bad serpentine belt can indirectly affect the transmission.


So, what causes a serpentine belt to break? The common causes include misalignment of connected pulleys, faulty alternator bearing,  oil leaks, and excessive wear.

Signs of a bad serpentine belt include overheating, squealing/whining noise, oil drops from the engine bay, and visible cracks on the belt’s body. You should fix and replace a broken serpentine belt as soon as you start noticing the signs.

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