Understanding All the Drive Belts in Your Car

Your car’s engine has a number of mechanical parts attached to it that perform essential functions like delivering power (the alternator), cooling your engine (the water pump), helping you to drive more easily (the power steering pump) and keeping you comfortable (the air conditioner compressor). Without a drive belt, none of these parts would work.

The purpose of drive belts is to deliver power between different engine components. They work by means of friction between the belt and pulley, which is why loose belts can cause various components to work poorly, or not at all.

That’s a very basic overview of car belts, and by no means all-inclusive. Let’s talk in a bit more detail about different types of belts and how they work in your car.

Here is an overview of the most common types of drive belts:

V-Belts

Some vehicles have multiple belts, called v-belts, that come off the crankshaft of the engine to drive the alternator, the air conditioning compressor, the power steering pump and the water pump. In older vehicles, v-belts were the standard.

Advantages of the v-belt system are:

  • Belts are short and not likely to slip.
  • If one belt fails, the entire vehicle doesn’t end up off-line.

Disadvantages of the v-belt system are:

  • Auto supply stores may not stock a full range of belts, and they may need to be special-ordered.

  • Belts will usually wear at about the same rate, so you could end up having to replace several belts within a short time frame.

Serpentine belts

A serpentine belt is a single, long belt that drives all the engine components that would otherwise be powered by multiple v-belts. Serpentine belts are most common in newer cars, and are essentially the standard for the modern vehicle.

Advantages of serpentine belts are:

  • No chance of multiple belt failure.
  • Easy to replace.

Disadvantages of serpentine belts are:

  • Multiple accessories can be affected if the belt loosens.
  • When the belt fails, the entire engine is off-line.

Timing belts

The timing belt is also sometimes called a camshaft drive belt or a Gilmer belt. It is a notched belt, made of rubber, that enables the crankshaft to turn the camshaft, and opens and closes the engine valves synchronously with the pistons. In late model vehicles, the timing belt has essentially replaced the metal timing chain.

The advantage of the timing belt over the timing chain is that if the timing belt fails, there is less potential for damage to valves and pistons.

Symptoms, causes, and effects of failed or failing drive belts

  • V-belts: If a v-belt is failing, it will squeak, and accessories may not work properly. If it fails, the accessories that it powers will stop working. Causes can include ordinary wear or fluid contamination.

  • Serpentine belts: If a serpentine belt is failing, accessories may not work properly, car may be hard to start or not start at all, and the belt may emit a squeaking, screeching or chirping sound. Causes can include cracking, wear or stripping, fluid contamination and poor belt tension.

  • Timing belts: If a timing belt is failing, your car may idle rough, or you may hear a slapping sound from the motor compartment. If it fails, your car will not work at all. There is also a possibility of serious damage to the valves and pistons. Causes can include wear, slipping or fluid contamination.

Common enemies of drive belts

Road dirt, oil, water, and excessive heat are all enemies that can cause drive belt problems, so you should make sure that your car isn’t leaking oil, and that when you’re topping off your oil you do it carefully. Make sure that your engine undercover isn’t missing or damaged, since it is your first line of defense against contaminants that you can pick up on the road.

Recommendations

You should have your vehicle checked by a mechanic regularly in order to determine if your belts need to be adjusted or replaced. Timing belts are generally long-lived, but given the potential consequences if the timing belt fails, the importance of regular check-ups cannot be over-estimated. Serpentine belts usually need to be changed about every 50,000 miles. It makes no sense to keep driving with a worn or damaged belt, because eventually, it will break and you’ll end up stranded and possibly needing expensive repairs


Next Step

Schedule Serpentine/Drive Belt Replacement

The most popular service booked by readers of this article is Serpentine/Drive Belt Replacement. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Recent Serpentine/Drive Belt Replacement reviews

Excellent Rating

(4,626)

Rating Summary
4,424
115
22
16
49
4,424
115
22
16
49

Behrak

9 years of experience
211 reviews
Behrak
9 years of experience
Mercedes-Benz C350 - Serpentine/Drive Belt Replacement - Duluth, Georgia
Knowledgeable and punctual. Even gave me some recommendations of what I need to do with my car next. Thanks 
GMC Sierra 1500 - Serpentine/Drive Belt - Alpharetta, Georgia
Behrak was awesome!!! He was prompt and on time. He provided great customer service and fixed what was needed. I highly recommend him and this company!!! My truck runs and sounds GREAT!!!!

Matthew

33 years of experience
1020 reviews
Matthew
33 years of experience
Saab 9-3 - Serpentine/Drive Belt - Williamsburg, Virginia
Once again I’m very pleased with the professionalism and skill of Matthew and the service of level of this company. Highly recommend for both quality and convenience.
Mazda CX-7 - Serpentine/Drive Belt - Norfolk, Virginia
Matthew is the absolute best! He did a great job on my vehicle and had it running in no time! If I ever have an issue with my car again, I know which mechanic I'll be calling. Thanks for your work and professionalism.

Attila

19 years of experience
751 reviews
Attila
19 years of experience
Mercedes-Benz C300 - Serpentine/Drive Belt - Edison, New Jersey
Amazing experience, great guy explained everything, made sure everything working. All genuine parts.

PETE

22 years of experience
20 reviews
PETE
22 years of experience
Oldsmobile Alero - Serpentine/Drive Belt - Newark, Delaware
Pete was early witch is unheard of nowadays. Very polite and will answer any questions you have. Friendly and professional. Will be using him very soon for the rest of the recommended work. Thanks Pete 

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

Common Signs Your Drive Belt Is Loose
The most common sign of a loose drive belt is noise, and it can range from a barely audible squeak to an...
Common Signs Your Drive Belt Needs Replacement
A car drive or serpentine belt keeps your engine running smoothly. Unusual noises from the engine and visible belt wear means it needs replacement.
Bent Valves and Other Common Issues After a Timing Belt Snaps
Ignoring your timing belt can come with a high cost. Timing belts don’t often snap, but when they do, it can cause...

Related questions

1998 Nissan Cube (Japan) drive belt part number

The Nissan Cube was not sold in America until 2009. This model was a third generation compared to Japan's 1998 version which was the first generation. You may have to call the dealer or a local parts store to see...

honda civic emitting high pitched noise under engine

It sounds like your accessory drive belt is loose and needs tensioned. If the belt has too much slack it will squeal. Over time, the rubber belt wears out and stretches. If it has cracks or splits the belt will...

2006 Toyota Camry wont start after overheating due to missing radiator cap.

Sounds like the water pump went bad and broke the timing belt and now the engine will not start. Have the engine timing checked and the water pump to see if it is broken.

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com