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What Happens To A Car When The Serpentine Belt Breaks?

October 16, 2021

Ever wondered what happens to a car when the serpentine belt breaks?
If an explosion comes to mind, the answer is no — your engine won’t explode. 

While the serpentine belt is responsible for powering vital engine accessories (including the water pump), it takes a bit more than a broken belt for your engine to burst. 

So, what does happen when the serpentine belt breaks?
Can the car even start with a broken serpentine belt?

We’ll try to answer these questions and also clear up a couple of other serpentine belt FAQs

This Article Contains:

Let’s get cracking!

What Happens To A Car When The Serpentine Belt Breaks?

The serpentine belt is built to last and isn’t prone to failing. 
However, it does wear down with time and use. 

If your serpentine belt breaks while you’re driving, you’ll likely hear some banging in the engine bay as it snaps and starts to slap around before coming off. 

Because this drive belt powers a bunch of essential engine systems, here’s what else that’ll happen if it breaks:

1. A Sudden Loss Of Power Steering Assist

Your power steering assist results in easier steering, which is why you can smoothly maneuver a 4,000 lb car. But if your serpentine belt breaks, the power steering pump stops functioning, and your steering wheel will start to get heavier

It won’t be very noticeable at high speeds. 
However, the slower you get, the more that steering wheel will reflect the weight of the vehicle. 

Loss of power steering is not something any driver wants, especially when maneuvering in heavy traffic.  

2. The Alternator Stops Powering Electrics

The alternator powers all the vehicle electrics and recharges the car battery. 
If the serpentine belt breaks, the alternator stops generating electrical power

If that happens, your headlights will dim, the radio won’t work, and the battery will die. The battery warning light will also turn on because your battery isn’t being charged. 

3. The Water Pump Ceases Circulating Engine Coolant 

The water pump circulates the engine coolant through the cooling system. 

A broken serpentine belt means your engine loses that cooling factor if it powers your water pump. Your car’s engine will start to overheat rapidly as a result. 

The temperature gauge will rise into the red zone, and the Check Engine light will illuminate once temperatures exceed safe levels. 

Note: Sometimes the timing belt drives the water pump, and you won’t face this problem.

4. Your Vehicle Goes Into Limp Mode

Your engine computer may initiate “limp mode” to protect your car from further engine damage. 

If your car goes into limp mode, you’ll notice a marked drop in engine performance, and your Check Engine light will pop on.

5. The Air Conditioner Stops Working 

Your air conditioning compressor will stop running. 
That means the air conditioner won’t work, and cabin cooling will fail

Fortunately, air conditioner failure isn’t a showstopper if the weather is good and you can roll down the windows. 

However, if you live in a hot climate and there’s heavy rain, your windshield and windows will fog up, obscuring the view and making driving extremely difficult. 

Clearly, a broken serpentine belt results in many essential components failing.
So what should you do if the serpentine belt breaks while you’re driving?

What Should I Do If My Serpentine Belt Breaks While I’m Driving?

Your engine won’t stall immediately, but you should pull over at a safe spot as soon as possible. The potential for difficulty in steering and the risk of an overheated vehicle engine is more than reason enough to stop.

Reduced vehicle performance, a heavy steering wheel, or that Check Engine light flashing would be more than fair warning that something is wrong. Not to mention the snapping and banging sounds from your engine bay when the drive belt breaks. 

Once you’ve stopped in a safe location, call for a mechanic or roadside assistance. Also, if the car’s serpentine belt is dangling in the engine compartment, remove it before moving the vehicle elsewhere to prevent further damage. 

Now that you have a good idea of what happens to a car when the serpentine belt breaks, let’s go over some FAQs. 

6 Serpentine Belt FAQs

Here are a couple of answers to questions you might have about the serpentine belt:

1. How Does The Serpentine Belt Work?

The serpentine belt delivers rotational energy from the engine crankshaft to all the engine systems. 

It’s also called the accessory drive belt, fan belt, or alternator belt because it drives the alternator, power steering, air conditioning compressor, and (sometimes) the water pump. 

To get all these engine systems functioning, the car’s serpentine belt works with a set of pulleys; pulleys on the engine accessories, a belt tensioner pulley, and an idler pulley or two. 

As the crankshaft rotates, the serpentine belt also rotates these other pulleys, powering the accessory.

What about the idler pulley and belt tensioner?
The idler pulley helps create enough wrap angle to prevent belt slippage from the other pulleys. And the belt tensioner (or automatic tensioner) provides the necessary belt tension for the serpentine belt to perform optimally. 

Here’s another thing — don’t confuse the serpentine belt with the timing belt. 
The serpentine is a drive belt and is located outside the engine. However, the timing belt is inside the engine, keeping the camshaft and crankshaft in sync. 

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

There are a couple of factors influencing the answer to this question, but on average, your car should be able to run between 20-90 minutes with a broken serpentine belt. 

The engine will overheat faster without a functioning cooling system on a hot day, so your driving window is less. 

But if it’s cold weather and your battery is fully charged, you might be able to keep that vehicle engine running a little longer than 90 minutes before the battery goes flat. That might be enough time to get to a nearby mechanic. 

Keep in mind that all electrical and electronic systems should be off to minimize battery drain, and that your steering wheel is going to feel way much heavier. 

3. Can A Car Start With A Broken Serpentine Belt?

Yes, a vehicle can start with a broken serpentine belt, assuming the battery is fully functional. The starter motor and ignition system will crank the car’s engine to get the combustion process started. 

However, you’ll need the serpentine belt if you want your car running for long periods. 

4. Can I Drive With A Worn Serpentine Belt?

Yes, you can. 
But if you know you have a worn belt, it’s better to get a serpentine belt replacement

There’s no reason to knowingly risk your vehicle and your own safety driving with a bad serpentine belt. Belt failure can occur anytime, and the consequences may be dangerous.

The serpentine belt typically will need inspection and replacement around 60k to 90k miles of usage. Being proactive about getting an old belt checked can prevent the hassle and potential danger of ending up with a broken belt. 

5. What Can Cause Serpentine Belt Failure?

Serpentine belt problems are typically caused by one or a combination of these things:

Premature failure can occur from uneven drive belt wear if the serpentine belt is misaligned.  

If the tensioner or pulleys are worn or damaged, they could cause a loose serpentine belt that might just fall off instead of breaking. Poor serpentine belt tension can affect the engine accessories, and the power steering pump or alternator won’t function properly.

A belt replacement might not solve a slipping belt problem if the tensioner and pulley system isn’t serviced as well. Make sure to get a reliable mechanic who’ll be thorough when replacing your old belt.  

6. What Are The Signs Of A Bad Serpentine Belt?

The good news is, the serpentine belt displays apparent signs of wear well before it will break. Here are a couple of symptoms you should be alert for:

If you notice any of these, it might be time to call the mechanic and get a serpentine belt replacement.

Closing Thoughts

It can be somewhat nerve-wracking if your drive belt breaks, especially if it happens at high speeds. The best thing to do is not panic and know that your vehicle will keep running for a bit while you get it to safety. 

To avoid this scenario, good car care is essential. 
If you’re looking for an easy solution to serpentine belt issues (whether it’s already broken or you want it checked), RepairSmith can help you!

RepairSmith is a mobile mechanic repair and maintenance service available 7-days a week, offering easy online booking and a 12 month, 12,000-mile warranty

Just contact them, and RepairSmith’s ASE-certified mechanics will hop on to wherever you are to help you out ASAP!