Do all engines have serpentine belts?

Not exactly. Serpentine belts are common in many modern internal combustion engines, but they are not universal. Some engines use multiple belts or timing-driven designs, and many electric or hybrid systems operate without a belt to drive propulsion accessories.

What a serpentine belt does in most engines

In a typical modern engine, a single long serpentine belt winds around several pulleys to drive the car’s essential accessories. It keeps the system compact and reduces the number of separate belts that could fail at once.

The belt typically drives the following components:

• Alternator


• Power steering pump


• A/C compressor


• Water pump (in many engines; some designs place the water pump on a timing belt/chain instead)


• Belt tensioner and idler pulleys

Because the belt ties these functions together, a failure can quickly affect charging, steering assist, cooling, and climate control. Replacement intervals vary by vehicle but commonly fall in the 60,000–100,000-mile range, and signs of wear include cracks, fraying, squealing, or loss of tension.

When you might not see a serpentine belt

Some engines use a different arrangement for driving accessories. Older cars and many trucks relied on separate belts for individual components. Others use a timing belt or chain to synchronize the engine’s cam timing, while the water pump and other accessories may be driven by belts or directly by the engine. In modern electrified powertrains, you may not see a belt at all driving propulsion-related components.

Alternative drive configurations

The landscape of engine accessory drives includes several common configurations:

• Multiple V-belts: separate belts for each major accessory, common on older or certain vehicles.


• Timing belt or timing chain for cam timing (separate from any accessory drive); some engines also have a belt for the water pump in addition to the timing drive.


• Beltless/electric accessory drive: many hybrids and almost all EVs rely on electric motors or electrical pumps for accessories, reducing or eliminating the need for a serpentine belt.


• Hybrid variations: in some hybrids, the internal combustion engine still uses a belt to drive accessories, but the rest of the system may be electrified, or the belt may be used only under certain conditions.

These configurations reflect varying design goals, including cost, efficiency, packaging, and the push toward electrification. Beltless designs reduce maintenance and noise, while belt-based systems remain common for their simplicity and lower upfront cost.

Impact on maintenance and what to watch for

For vehicles with a serpentine belt, proactive maintenance is important. Inspect belts for glazing, cracks, fraying, or missing chunks; listen for squeals that may indicate a slipping belt; and replace the belt according to manufacturer recommendations, typically at tens of thousands of miles. If a belt breaks, it can disable multiple systems all at once.

Summary

You cannot assume every engine uses a serpentine belt. The majority of modern internal-combustion engines do, but many older designs and some hybrids use multiple belts or timing-driven systems, and pure electric vehicles typically have no belt-driven propulsion accessories. The trend toward electrification is driving more beltless designs, but belts remain a common, cost-effective solution for many installations today.

What is the belt called that runs the alternator?

The belt that runs the alternator is called the serpentine belt, also known as the drive belt. It's a single, winding belt that powers multiple engine accessories, including the alternator, power steering pump, water pump, and air conditioning compressor.
 

• Function: The serpentine belt transfers mechanical power from the crankshaft pulley to the alternator, which generates electrical power for the car's systems. 
• Name origin: It gets the name "serpentine" from the winding, snake-like path it takes as it wraps around the various pulleys. 
• Modern vs. older cars: Most modern cars use a single serpentine belt, while some older cars may use separate belts for different components. 

How often should a serpentine belt be replaced?

A serpentine belt should be replaced every 60,000 to 100,000 miles, or every four to six years for drivers who cover less mileage. However, it's crucial to inspect the belt for signs of wear like cracks, fraying, or squealing noises, as a failure can cause systems like the power steering and air conditioning to stop working. 
This video explains how to identify signs of a worn-out serpentine belt: 59sHomeowner RepairYouTube · Dec 16, 2018
Mileage and age

• General rule: Replace the belt between 60,000 and 100,000 miles.
• Low mileage: If you drive less than 10,000 miles annually, a replacement every four to six years is a good proactive measure. 

Signs of a failing belt

• Noise: Squealing or chirping sounds from the engine, especially when the car starts or the air conditioning is on.
• System failure: Power steering becomes sluggish or fails, or the air conditioning stops working.
• Visible damage: Cracks, fraying, or missing chunks on the belt itself.
• Other indicators: A malfunctioning battery or the engine overheating can also be symptoms. 

What to do

• Routine inspection: Have the belt inspected during regular maintenance, such as during an oil change, especially once you hit 60,000 miles. 
• Proactive replacement: It's often recommended to replace the belt proactively at the recommended service interval to avoid an inconvenient and potentially dangerous breakdown on the road. 

Will an engine run without a serpentine belt?

No, an engine cannot run long-term without a serpentine belt because it drives the water pump and alternator. Driving even for a short distance without the belt will cause the engine to overheat and the battery to die, as the water pump will not circulate coolant and the alternator will not recharge the battery.
 
This video demonstrates what happens when a car is driven without a serpentine belt: 1mAuto Repair GuysYouTube · Sep 6, 2022
Risks of driving without a serpentine belt

• Engine overheating: The serpentine belt drives the water pump, which circulates coolant. Without it, the engine will overheat very quickly and can sustain severe damage. 
• Dead battery: The alternator, which recharges the battery, is also powered by the serpentine belt. Without it, the battery will deplete its charge, and electrical systems, including the engine control unit, will shut down. 
• Loss of power steering and other systems: The belt also powers the power steering pump (in some vehicles) and the air conditioning compressor. Driving without it will result in a loss of power steering assist, making the steering wheel very difficult to turn. 
• Safety hazard: The loss of power steering, coupled with the risk of the engine shutting down, makes driving without a serpentine belt extremely unsafe and a serious accident risk. 
• Engine damage: The potential for overheating and subsequent damage, such as warped cylinder heads or a blown head gasket, can lead to extremely expensive repairs. 

This video shows the consequences of driving without a serpentine belt in a BMW: 58sAuto Repair GuysYouTube · Aug 21, 2022
What to do if the belt breaks
If your serpentine belt breaks while you are driving, pull over to a safe location immediately. Do not attempt to drive the vehicle any further than necessary, and call for a tow truck.

Do all vehicles have a serpentine belt?

No, not all cars have serpentine belts, but most modern vehicles do. Older cars often used a series of individual V-belts, while some modern cars may have a timing chain instead of a timing belt, but they still have a serpentine belt for accessories like the alternator, water pump, and air conditioning compressor. 
This video explains what a serpentine belt is and why it's important: 52sHow a Car WorksYouTube · Mar 20, 2020

• Modern cars: Almost all modern gasoline and diesel engines use a single serpentine belt to drive multiple accessories. 
• Older cars: Many older vehicles used multiple V-belts, with each belt driving one or a few components. 
• Electric vehicles (EVs): EVs do not have a serpentine belt because they don't have an internal combustion engine. 

You can watch this video to learn how to identify if your car needs a new belt: 1mScotty KilmerYouTube · Mar 28, 2021