Drive Belts

Your car runs on numerous mechanical parts and gizmos and among these are the drive belts! These are not the one that keeps your pants up but, there are different types of mechanical belts, each having a very specific role to perform, like cranking the alternator, power the AC, running the water pump and many more.
In this aptly named GoMechanic Basics post, we are going to look into various types of mechanical car belts.
Buckle up! (see what we did there?)

Serpentine Belt

Serpentine belt is also known as multi-v, poly-v, multi-rib or just plain-simple drive belts. A serpentine belt is a long snake-like winding belt that wraps around various peripherals of the car engine and is responsible for powering the AC compressor, power steering pump, radiator fan, alternator etc.
The serpentine belt draws power from the crankshaft via the crankshaft pulley and is guided by a belt tensioner or an idler pulley.
Serpentine belts are made of heavy-duty grade rubber, with newer belts being made of EPDM or Ethylene Propylene Diene Monomer, which claim to last upto 100,000 kms. In reality, most belts show signs of wear after 60,000 kms mark and it is recommended to replace the serpentine belt after 80,000 kms.

Advantages of serpentine belts:

  1. Serpentine belts are more efficient and use less space in the engine bay, allowing for a more compact engine form.
  2. Serpentine belts are easily available and cheap to replace as they don’t require multiple disassemblies.
  3. As the engine utilizes a single serpentine belt for various operation, there is no chance for multiple belt failure.
  4. Serpentine belts are self-adjusting type and require no manual adjustment.

Disadvantages of serpentine belts:

  1. A serpentine belt is a single belt powering numerous components, therefore, a failed belt will cause multiple component failure (AC, compressor, water pump etc).
  2. A loose belt will affect all the peripherals that are powered through the serpentine belt.

Signs for a failing serpentine belt:

  1. High-pitched squealing noise from the engine bay.
  2. Visible cracks and tears on the serpentine belt.
  3. Sudden component failure (Power steering, AC etc).


They are also known as wedge-type belts. Their name is derived from their shape which is roughly trapezoidal (like a “V”). They too draw power from the engine but unlike serpentine belt, they are limited to power only a few components usually one or two.
V-belts replaced the usage of flat belts which were inefficient. Due to their wedge type form factor, V-belts find a perfect usage in power transmission. Higher load pulling capacity, reduced torque tension are some plus points. V-belts are made up of hard rubber, neoprene, and urethane.

Advantages of a V-belts

  1. V-belts are shorter in length, unlike serpentine belts.
  2. V-belts power only a few components at a time, thereby no multiple component failure.
  3. If a single V-belt fails, other components won’t be affected.

Disadvantages of a V-belt

  1. V-belts are now being replaced by serpentine belts hence, are hard to find and expensive.
  2. All the V-belts in the car will more or less wear at the same rate. You will find replacing a lot of belts during a service.
  3. A loose V-belt can adversely damage the component it is powering.

Signs for a failing V-belt

  1. High pitch squealing noise similar to serpentine belts
  2. A component failure like the alternator not charging the battery
  3. Worn pulley bearings

Timing Belt

They are also called a crankshaft drive belt or a Gilmer belt. A timing belt is a toothed belt that performs the function of syncing the valves and cylinder with the pistons and the crankcase. The timing belt is not visible in the engine bay and is usually hidden behind an engine cover. Earlier, manufacturers used a timing chain to achieve the same goal, but due to efficiency issues, it got replaced by a timing belt.

Advantages of a timing belt:

  1. Less chance of adverse damage to the valves and the pistons
  2. Timing belts have high mechanical efficiency upto 98%

Disadvantages of a timing belt:

  1. A failed timing belt can cause catastrophic engine damage
  2. An out of sync timing belt can mess up the valve and piston timings

Signs for a failing timing belt:

  1. Rough idling or ticking noise from the engine
  2. Check engine warning or engine failure

How to take care of your car drive belts

  1. Keep the belts away from engine oil, water/moisture, debris etc
  2. Make sure the components are in good shape to avoid stress on the belts
  3. Always perform routine inspections and checks
  4. Replace periodically or when recommended

Congratulations! You have earned a black belt. This was all the basics you need to know on car belts.

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Akshat Ajeya

Lead, Content & Creatives at GoMechanic | Automobile Scale Model Collector | DIY guy | Consumer of many foods |


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