Serpentine Belt vs. Timing Belt – Repair, Symptoms

Belt systems in engines are very important. They have very special duties to make. But most people are thinking that all engines have one belt which is the timing belt. But it is not like this. There are two belts; a serpentine belt and a timing belt. Here you can learn about the serpentine belt and timing belt systems. If you are curious about the serpentine belt vs timing belt, you are at the right place.

What is Timing Belt?

timing belt.
Timing belt. Image Source:

We can start with the essentials. The timing belt is a main belt system that provides motion from the crankshaft to the camshaft. So, a proper alignment takes place between the crankshaft and the camshaft. This allows the engine to work well and smoothly way.

The importance of the timing belt comes from the timing of the engine. Most of the engines are working in the 4 times. Intake, compression, power, and exhaust. The time of the intake and exhaust valves that open and close must be adjusted very well. It depends on the timing of the system. The proper timing is very important in general.

The timing is provided by the timing belt as you understand from its name. It ensures the alignment of the crankshaft and camshaft. And the valves open and closes when they need to.

Difference between Serpentine Belt vs. Timing Belt

Serpentine Belt vs. Timing Belt
Serpentine belt. Image Source: Express car care.

So, the duty of the serpentine belt which is the second belt in the engine is quite different than the timing belt. Also, some of the sources are calling these belts the accessory belt, fan belts or drive belts.

Also, the serpentine belt is connected to these systems; alternator, water pump, air conditioning compressor, and power steering pump. They are also very important systems for the vehicle that we are driving. This is the reason why the serpentine belt is called an accessory belt.

The serpentine belt also takes power from the crankshaft just like the timing belt. And provides this power to the other accessories.

  • Alternator: The alternator is connected to the serpentine belt. It is responsible for the recharging of the battery.
  • Water pump: Also, circulation of the water inside the engine is very important for the cooling system The water pump that circulates the water is connected to the water pump system.
  • Air conditioning: You know that an air conditioning system must be connected with a compressor application. The compressor system compresses the coolant that provides the cooling and heating application. So, the compressor takes the power from the serpentine belt.
  • Power steering pump: The power steering system is a hydraulic system that has oil inside it. The hydraulic oil works at high pressure to help the driver to turn the steering wheel. And there is a pump system that increases the pressure of the system. So, the steering pump takes the power from the serpentine belt.

How to Spot a Belt? Serpentine or Timing?

You opened the bonnet of your car and looked at the engine. And you trying to understand which one is the serpentine or timing belt. We can give some differences between them in the construction of an internal combustion engine. Check the main differences between serpentine belt vs. timing belt.


There is a location difference between a serpentine and a timing belt in the engine. In most engine designs, the serpentine belt is located in front of the engine. And you can easily spot that it winds around the different pulleys that are connected to the different accessories.

But the timing belt is generally located behind the engine and it is generally under a cover. Because of it, locating the timing belt is harder than the serpentine belt.

So as you understand, in most cases, what you see when you open the bonnet of the car is the serpentine belt.


Also, you can conclude that they are made from the same material. They are not. The most common material that is used in the serpentine belt is polymer-based rubber. They have a composite structure in terms of hardness. The teeth are harder but the outer side of the serpentine belt is softer in general.

Also if we take a look at the material of the timing belt, the material is much more high quality and durable. In most cases, the timing belt is made from neoprene or fiberglass-reinforced rubber material.

The reason behind this difference, the timing belt is much more important and highly excessed to stresses. So, they are generally made of much harder materials.


Also, their structure is different. If you take a look at the teeth structures of these two belts, you can understand the difference between them.

The timing belt generally has shaped vertical grooves. It provides a much more effective attachment and very good timing between the crankshaft and the camshaft.

Also, the structure of the teeth of the serpentine belt is the V-shaped grooves.

From this difference, you can easily understand the difference between these two important systems.

As you understand, these are the general differences between the serpentine belt and the timing belt. And you will be able to spot the differences without any problem.

After that point, we can give some extra and additional information about these belt mechanisms.

Bad Serpentine Belt Symptoms

As we explained above, the proper working of the different engine systems is dependent on the serpentine belt. And if there is a problem with the serpentine belt, we can see various symptoms appear in these systems.

  • Overheating: The serpentine belt is connected to the cooling system of the engine. And if there is a problem with this belt, overheating may take place. This is because the water pump system is not working well.
  • Noises: Problems with the belts generally show themselves with noises. You can hear a squealing and chirping sound that comes from the belt mechanism.
  • Performance loss: Also the performance loss of the engine is one of the most common reasons for the bad serpentine belt. Because lots of important accessories that make the engine work well are attached to this belt.
  • Problems with air conditioning: As we explained above, the air conditioning system is connected to the serpentine belt system. If the serpentine belt does not work properly, the air conditioning compressor will not work properly. And you will feel it is a problem with the air conditioning system.
  • Battery problems: Without a working alternator, the battery will run out of charge. Because it does not receive power from the alternator. And also we know that the alternator is directly connected to the serpentine belt. If you have a problem with the serpentine belt, the alternator will not work properly.

In most cases, the change of the serpentine belt will solve the problems in general.

Bad Timing Belt Symptoms

Also, there can be problems with your timing belt application.

  • Performance loss: The problem with the timing belt mechanism can cause misfires, and stalls because of the uneven opening and closing of the valves. And you will not get the required amount of power from your engine.
  • Rough idle: Misfires and stalls can cause rough idle also. You may hear strange noises coming from your engine.
  • Noises: Like the serpentine belt, the bad timing belt can cause strange noises coming from your belt pulley systems.
  • Problems in start: When you try to start your engine, you will feel that you have a problem with starting your engine. Because the valve systems are not working well.

Also, changing the timing belt can solve most of these problems.

Replacement Costs of Timing Belt and Serpentine Belt

It can be very hard to give exact prices for the timing belt and serpentine belt replacement costs in general. They are very different systems that we need to apply to the engine system.

The model and the brand of your car have a profound effect on the prices. But we can give some ranges.

  • The replacement cost of the serpentine belt can cost around $200-$400. The belt itself will be around $50-$100. And the remaining cost will be the labor costs.
  • Also, the replacement costs of the timing belt are higher than the serpentine belt. Because a much higher number of elements must be detached from the system. The timing belt price can be around $100-$150 which is slightly higher than the serpentine belt. Because, as we stated above, the material of the timing belt is advanced. Because of the higher labor required, the replacement of the timing belt can be up to $1000-$1500.

As you can understand that the timing belt is a much more critical part if we compare it with the serpentine belt applications.

Do Cars Have Both Timing Belt and Serpentine Belt?

Yes. Because they have different duties in the engine. The timing belt is responsible for the alignment of the camshaft and crankshaft. And also the serpentine belt is responsible for the working of the engine accessories in general.

How Long do the Timing Belt and Serpentine Belt Last?

In most cases, the total lifespan of the timing belt and serpentine belt is around 60.000 to 100.000 miles. So in regular maintenance applications, mechanics check the belts regularly.

Conclusion on Serpentine Belt vs Timing Belt

We tried to explain all the important differences between the serpentine belt vs. timing belt. We wish you do not have additional questions in your head. But if you have, you can leave them below.

Check the other informative articles about the car and engine parts;

Badger Tool Belt Review and General Guide

Oil Filter Socket – What is It? How to Choose?

Oil Filter Housing – What is That? Complete Guide

Oil Filter Removal Tool – Selection Guide with Products

Spark Plug Socket Set – Buying Guide and Additional Infos

Uğur Uygun

Hello everyone, I am Uğur. I am a mechanical engineer who has experience in different R&D departments of HVAC companies. With my best friend, I decided to build this website to share out knowledge and experience. And also, I am interested in automotive. So, I am writing about automotive and automotive-related articles here. Sharing my knowledge and experiences on these topics is a very big pleasure for me. I am willing to answer all of the questions people have about these topics.

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