Engine drive belts, also known as accessory drive belts, are belts used to transfer power from the engine’s crankshaft to various components within a car such as an alternator, power steering pump, air conditioning compressor, and water pump.
These belts are made of rubber and are designed to be flexible, yet strong enough to transmit power effectively. In this article, our objective is to provide a comprehensive overview of Engine Drive Belts.
What Are Engine Drive Belts?
Engine drive belts are key parts in a car’s mechanical system. They help various engine accessories work together. These belts are usually made from strong rubber or high-grade synthetic materials. They transfer power from the engine’s crankshaft to other devices. These include the alternator, water pump, power steering pump, and air conditioning compressor.
The main job of engine drive belts is to keep critical accessories working when the engine is on. They act like silent conductors in a car, making sure every part works well together. This helps the car run smoothly and efficiently.
The design of these belts is quite smart. They are flexible yet strong, able to work well in the hot environment of the engine bay. Their shapes and lengths are carefully chosen. This ensures they fit well around the pulleys, reducing slippage and transferring power effectively.
What are the 2 drive belts?
In the realm of automotive engineering, the two primary types of engine drive belts are the V-belt and the serpentine belt, each with its unique design and function.
V-Belt:
The V-belt, also known as the fan belt, is the elder of the two, tracing its roots back to the early days of automotive engineering. It’s characterized by its trapezoidal cross-section, which provides a snug fit in the corresponding V-shaped grooves of the pulleys. This design ensures a stable grip, reducing the likelihood of slippage during operation. V-belts are typically employed in systems where there are multiple belts, each driving a single accessory.
The below images show a close up look of a V-belt and how it uses in a vehicle energy transmitting purpose.
Serpentine Belt:
On the other hand, the serpentine belt, a modern evolution, is a long, continuous belt that snakes around multiple pulleys, driving several accessories simultaneously. Its flat and multi-ribbed design provides a larger surface area for better grip and power transmission. The serpentine belt simplifies the belt system by consolidating multiple V-belts into a single belt, making maintenance and replacement a less daunting task.
The below images show a close up look of a old and new serpentine belts.
What are the 3 belts in a car?
In older or more traditional automotive designs, three separate belts might be employed to drive different engine accessories. These would typically include:
- Alternator Belt: This belt is crucial for charging the vehicle’s battery and powering the electrical system while the engine is running. It transmits power from the crankshaft to the alternator.
- Water Pump Belt: The water pump belt plays a vital role in the vehicle’s cooling system, driving the water pump which circulates coolant through the engine and radiator, thus preventing overheating.
- Power Steering Belt: This belt is responsible for providing the necessary power to the power steering pump, ensuring a smooth and responsive steering experience.
Each of these belts, though simple in appearance, is crucial for the seamless operation of the vehicle, underscoring the importance of regular inspection and maintenance to ensure their integrity and functionality.
Here I have mentioned about 3 belt types in the below table to have overall idea easily.
| Type of Engine Drive Belt | Description | Key Characteristics |
| Serpentine Belt | A single belt that drives multiple components within the engine | Shaped like a serpent, compact and made of durable, heat-resistant rubber material |
| V-Belt | A type of Engine Drive Belt that drives multiple components within the engine | Shaped like a V, made of rubber and reinforced with fiber cords, less commonly used in modern engines |
| Timing Belt | A type of Engine Drive Belt used to synchronize the rotation of the crankshaft and camshaft | Designed to maintain the correct timing between the crankshaft and camshaft, typically made of durable, heat-resistant rubber material |
The below images show a close up look of a timing belt and how it uses in a vehicle energy transmitting purpose.
What does the drive belt do?
1. Role in Engine Operation
Engine drive belts transfer power from the engine’s crankshaft to various components within the engine. This power transfer allows these components to operate efficiently, which helps to maintain the overall performance of the engine.
2. Power Transmission
Engine drive belts transmit using a combination of tension and friction. The friction between the belt and the pulleys it drives allows the power to be transmitted from the crankshaft to the components.
3. Engine Component Interaction
The interaction between the engine drive belts and various components in the car such as the alternator is critical to the proper functioning of the engine and overall performance of the car.
Symptoms of a Failing Engine Drive Belt
1. Squeaking or Slipping Belts
If there is a squeaking or slipping sound coming from the engine, that can be a sign of a failing engine drive belt.
This sound is often caused by the belt slipping on one of the pulleys it drives, which can occur when the belt is worn or damaged.
If the belt is slipping, it may also cause a decrease in the power being transmitted from the crankshaft to the components, leading to decreased performance.
2. Cracks or Fraying on the Belt Surface
Also, if you can see cracks or fraying on the surface of the belt, it can be a sign that the belt has reached the end of its life and needs to be replaced.
The cracks and fraying can occur due to age, heat exposure, or improper tension, and can cause the belt to fail suddenly, leading to engine malfunction.
3. Engine Malfunction
A failing engine drive belt can also cause engine malfunction, including a decrease in engine performance, stalling, and engine failure.
If the belt is slipping or has failed, it may cause the components it drives to stop functioning, leading to decreased engine performance or a complete engine shutdown.
It is important to have a failing engine drive belt inspected and replaced as soon as possible to avoid these potential problems.
Engine drive belts replacement
It is recommended to replace engine drive belts every 50,000 to 60,000 miles, or as specified by the manufacturer, to ensure that they are functioning properly.
How much does it cost to replace drive belt?
The cost of Engine Drive Belt replacement can vary depending on the make and model of the car, as well as the type of belt being replaced. On average, the cost of Engine Drive Belt replacement can range from $200 to $500, including labor costs.
However, this cost can be higher for luxury or high-performance vehicles, or more complex Engine Drive Belt systems.
Why is it Important to install the driving belts properly?
Proper installation of engine drive belts is essential for ensuring their proper functioning and longevity.
Improper installation, such as incorrect tension or misalignment of the belt, can cause the belt to slip or fail, leading to engine problems.
It’s important to have engine drive belts replaced by a professional mechanic with experience in this area, to ensure that they are installed correctly and that the engine continues to operate smoothly.
How to replace the drive belt?
If a belt is worn or damaged, it cannot be repaired and must be replaced. A mechanic may be needed if you are not familiar with the engine. If you choose to replace the belt yourself, be sure to follow the steps below.
- Step 01: The car needs to be turned off and cooled
- Step 02: Consult your belt routing diagram
- Step 03: Use a wrench, ratchet, or special tool to remove the tensioner.
- Step 04: Replace the old belt with a new one of the same length and width, making sure the grooves match up with the pulleys.
- Step 05: Tighten the belt and check for proper tension by pulling it. The belt should not stretch more than 1 inch.
- Step 06: Before starting the car, check the routing, straightness, and tension of the belt.
- Step 07: After replacing the belt, start the car and observe the belt rotation to make sure it is functioning properly.
Final Thoughts
Regular inspection and maintenance of engine drive belts are important for detecting potential problems early and ensuring their proper functioning.
In the event of a failing Engine Drive Belt, it’s important to have it replaced promptly by a professional mechanic to avoid engine problems.
John Smith, a Los Angeles-based car specialist and automotive writer, boasts over 20 years in the industry. With a background as a master technician and a decade-long writing stint at notable automotive publications, John now shares his expansive knowledge on CarFinite, simplifying car maintenance for readers.