What Causes A Serpentine Belt To Break? – What You Need To Know

The serpentine belt plays the role of driving essential parts of the engine. If the belt is damaged or broken, it will cause the vehicle’s driving system to stall and affect the vehicle’s ability to operate.

A new belt usually always makes the engine run smoothly, but if it’s been used for a certain period, the possibility of the belt being deformed due to stretching and slipping is common.

So what causes a serpentine belt to break?

You need to check the cause of the belt’s rapid damage, find a reasonable remedy, reduce the cost of repair and replacement of materials, and make the machine work more efficiently.

What Is The Serpentine Belt? 

what causes a serpentine belt to break
Serpentine Belt


The serpentine belt, also known as a belt, drives all the subsystems at the front of the engine. It should not be confused with timing belts, which serve an entirely different purpose.

The role of the serpentine belt is to transmit power to many important peripheral components through belt tensioner pulleys driven from the engine’s crankshaft pulley.

This belt turns the generator, water pump, air conditioning compressor, and sometimes the power steering pump and cooling fan.

If the serpentine drive belt is damaged, the accessories may not work correctly, the car may be challenging or won’t start, and the belt may squeal or squeak.

Serpentine belt issues’ possible causes include cracking, wear or tear, liquid (oil) contamination, and poor belt tension.

Features Of Serpentine Belt

  • In terms of form, the serpentine belt has a closed continuous long line shape. The smooth outer surface is customizable; the inner surface is roughened to increase friction with the pulley.
  • Regarding materials, serpentine belts are mainly made from natural or artificial rubber. A good quality serpentine belt must meet the following criteria: low elongation, high friction resistance, high heat resistance, and stable operation in harsh conditions.

In recent years, serpentine auxiliary belts have become the preferred choice. Its design is flat, wide, and multi-ribbed, can power several components, and take up less space.

With careful engineering, some accessories can be rotated with less friction from the back of the belt to save more fuel.

What Causes A Serpentine Belt To Break? 

why did my serpentine belt break
why alternator belt broke

“How does a serpentine belt break?” or “why did my serpentine belt break?” These are the questions that car drivers ask a lot with their vehicles.

According to research, we have found five main causes of the alternator belt broke, including the broken connection to the serpentine, oil leakage, weakened serpentine belt, poor hydraulic belt tensioner, and bad pulleys.

Details are:

The Connection To The Serpentine Belt Is Broken

Serpentine belts are connected to several pulleys, accessory drive belts, and other electronic equipment such as generators, water pumps, power steering pumps, air conditioning compressors, etc.

If one of the above devices fails, it will directly increase the bad bearing on the belt. It will break when the fan belt can no longer withstand the impact force.

Serpentine Belt Weakens Due To Extended Use

When you start the car, the serpentine belt will continuously rotate until you stop the vehicle. Therefore, this belt has a certain lifespan based on the material used to make it.

Older generations of serpentine belts were made of Neoprene rubber, and their lifespan was only about 50,000 miles.

Newer ones are made from Ethylene Propylene Diene Monomer (EPDM) rubber, and their lifespan can be up to 100,000 miles or more.

The serpentine belt is likely no longer safe if you’ve driven more than 100,000 miles.

Please replace the serpentine belt immediately with a new one from a quality brand to avoid a brand-new serpentine belt broke.

Leaking Oil

Oil leaks in the engine compartment cause many problems for your serpentine belt.

If this condition persists and causes the serpentine belt to become soaked with oil, it will cause the belt to stop performing its functions and gradually fail.

Your job is to find the oil leak and fix it immediately. If the Serpentine belt is oily, it should be replaced with a new one.

Hydraulic Belt Tensioner Broken

A miniature shock absorber operates the hydraulic serpentine belt tensioner.

If the automatic belt tensioner or shock absorber is damaged, it can cause the serpentine belt to break due to the increased pressure and workload on the belt.

It is essential to repair the hydraulic belt tensioner before installing a new serpentine belt.

Pulleys Are Not Well Aligned

Poor alignment of idler pulleys can cause the serpentine belt to wear out faster and fail before its intended life.

It is tough to detect a deviated pulley; you must bring the car to a mechanic to check. Signs of a misaligned pulley include increased wear on one side of the belt and deafening driving noises.

What Are The Signs Of A Bad Serpentine Belt?

There are 5 most common serpentine belt symptoms that a bad serpentine Belt is working in your engine and causing a premature failure:

  • The most common sign of a failing or stopped serpentine belt is the warning light on the dashboard coming on.
  • Heavy steering is also a sign because the serpentine belt powers the power steering pump.
  • Visible signs of wear are cracking on the serpentine belt body, similar to the ribbed belt.
  • When the car is working, you hear an annoying creaking sound indicating a noisy belt is here.
  • Another sign is that the air conditioner in the car is not working. The serpentine belt keeps the AC pump in good working order, so when the belt breaks, the air conditioner stops immediately.

When To Replace the Serpentine Belt? 

We recommend that you observe and check the serpentine belt on most vehicles whenever you change the oil.

It would be best if you planned on changing the belt every 5 years or after the vehicle has done 100,000km. Replacement is inexpensive and usually only takes a few minutes.

How To Change The Serpentine Belt Correctly At Home?

brand new serpentine belt broke
Way To Fix Serpentine Belt Correctly At Home?

Although it is only a very small detail on a car, if the serpentine belt is damaged, it will significantly affect its performance.

Therefore, car owners must check the belt and change it when necessary to ensure a smooth travel route.

  • First, car owners must determine the appropriate serpentine belt parameters and size by looking at the information on the wire surface. Take note of the parameters and go to reputable auto parts supply stores to buy.
  • After you have a standard serpentine belt, open the engine compartment and find where the wire needs to be replaced. Use a wrench to loosen the shaft nut and remove the old belt.
  • Put the belt in the correct position; the two ends match the two grooves of the alternator pulley and tighten the screws on both sides until the belt is evenly taut. Rotate the cord by hand to check the serpentine belt tension.


How Long Can My Car Engine Run With A Broken Serpentine Belt?

A car engine can run between 20 to 90 minutes with a broken serpentine belt.

If the serpentine belt breaks, many parts of the machine will “strike,” such as the wheel bearing, air pump, engine overheating, oil leaks, etc.

They force the owner to unload it after a maximum of 90 minutes to reset the shafts and pistons.

What Should I Do If Your Serpentine Belt Breaks While You’re Driving?

As mentioned above, after the serpentine belt breaks, each car owner can run their car for a minimum of 20 minutes.

Therefore, the most important thing right now is to find the nearest garage and take your vehicle there for quick repair with transparent pricing.


What causes a serpentine belt to break? As mentioned above, this problem can be due to oil leakage, poor hydraulic belt tensioner, pulleys, and serpentine connection.

If you are experiencing one of these causes, have your vehicle inspected and fitted with a new part in its place for optimal car performance.

Hopefully, the above maintenance tips will significantly help you drive and maintain your vehicle safely.

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