How To Diagnose A Failing Serpentine Belt

A serpentine belt should last between 50K and 100K miles. Although sometimes it can fail early.

If you think that you may have a failing serpentine belt, you want to diagnose the issue ASAP. It's much better to replace it before it fails completely. Once it fails, you'll be stranded. (Speaking of replacing serpentine belts, we offer genuine OEM replacement belts at wholesale pricing!)

Luckily, diagnosing a bad serpentine belt is very easy. We'll walk you through the process in this guide.

Telltale Signs Of A Bad Serpentine Belt


If you notice any of the following symptoms, chances are your serpentine belt isn't in good shape.

  • Squealing noise coming from the front of the vehicle
  • A/C system not cooling well
  • Power steering not providing full power
  • Engine running warmer than normal

If you're experiencing any of those symptoms, please find some time to inspect your serpentine belt ASAP.

Inspecting Your Serpentine Belt

You don't need any fancy tools to inspect the serpentine belt in your Toyota. All you need to do is to:

  1. Pop the hood
  2. Find the serpentine belt
  3. Give it a thorough visual inspection

The serpentine belt should be either on the front of the engine, or on the side (left or right). The location depends on your Toyota model. Sometimes you would need to remove the engine cover. You should have a full view of the entire belt. Toyota always designs its serpentine belts to be easily accessible.

What To Look For

When you have the serpentine belt in front of you, grab a flashlight and then give it a close visual inspection. Look for the following:

  • Cracks
  • Frayed edges
  • Missing chunks
  • Rib separation
  • Uneven rib wear
  • Damaged ribs

If you find any of these, your serpentine belt is no longer good. You need to replace it as soon as possible.

If the belt looks good, check the tension. Do this by pushing on a long section of the serpentine belt. It should have about 1/2" of play. If there's too much play, the belt is loose. If there's too little play, the belt is too tight. Try adjusting the tension to see if it solves the problem.

What Happens When You Don't Replace A Bad Serpentine Belt?

Replacement belt

If you have a bad serpentine belt, you want to replace it ASAP. If you don't replace it, you'll experience we listed above. As the belt wears more, those problems will worsen. If the belt finally breaks, you won't be able to drive your car at all. Fortunately, it's pretty easy to replace a serpentine belt. This tutorial will walk you through the process of replacing the belt.

Written by Jason Lancaster