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What is a Serpentine Belt?

This is the belt on your car that drives the accessories. In order to technically be a serpentine belt, it must drive multiple accessories. Things like:

  • Power steering pumpserpentinebeltdiag
  • Alternator
  • Air conditioning compressor
  • Water pump
  • Super charger (if applicable)
  • Smog pump (this is an emissions control on older cars)

The serpentine belt can also be called a ribbed belt, Vee-belt, or a multi belt. The are kept tight by a tensioner.  It can be be tensioned automatically, or have the tension manually set. They may also use pulleys that simply route the belt properly.

Why is it important?

The serpentine belt has a pretty serious job.  With out it your car will will have a dead battery and may even over heat.  Plus we all love our a/c, especially here in the south.

A broken serpentine belt can surely lead to you being stranded. At best your battery will be dead.  At worst, you can have issues with engine damage.  It is rare for a serpentine belt to break in a way that causes engine damage, but it can happen.

How do you know you need to replace it?

Many times a worn serpentine belt can be easily seen. If you can see the belt while it is on the car, you may only see a small section of belt. The good thing is, you see it at the most stressed point, rapped around a pulley. That will allow you to see cracking of the belt easier.

Luckily serpentine belts only fail in a few ways:

  • They break completely. Be careful about only replacing the belt. There may be a pulley that has failed causing the belt to break.
  • Cracking, this is the most common way to know your belt is due for replacement.
  • Noisy, sometimes a belt that is making noise just needs to be replaced.
  • Contamination. This is from other issues with the car. If a water pump leaks coolant, or there is oil leaking on the belt, it is best to replace it. Contaminates can penetrate the belt and cause failure.

So, do I really need this service?

This one is not an easy YES/NO question.  Do you need a properly functioning belt, YES.  Do you have to replace it right now, maybe not.

This is a part that I highly recommend you ask your mechanic to show you. If it looks like it is full of cracks, or is soaked in oil/coolant, replace it. If the belt looks okay, and your mechanic can not show you the issue, it may be fine to wait.