New Serp Belt Tensioner Already Squeaking? Here’s What You Should Check

Are you working on a car with a brand new serpentine belt that’s making noises? If so, we’ll help you troubleshoot the issue.

belt tensioner

A serpentine belt should make a low humming sound. It’s a good sign that the belt is:

  • In good shape
  • The right length
  • Tightened to the correct tolerance
  • Installed correctly

If you hear a squeaking, squealing, or chirping sound, then something is wrong. So the first thing you want to do is to identify the noise. The noise sounds like squeaking at first. But if you really listen, you may be able to determine whether it’s chirping or squealing.

The type of noise can tell you a lot about what’s wrong with the serpentine belt.

Identifying The Noise

In some cases, it may be easy to differentiate between chirping and squealing. In other cases, it’s much harder.

Chirping is a high-pitched noise of short duration. This noise is easier to identify when the engine is idling. Once you have the car in gear, the belt moves faster. The chirping noise will blend into one noise, which is easy to mistake for squealing.

If you’re not sure which type of noise your serpentine belt is making, you can try this trick:

Grab a water bottle and then spray the rib side of the belt while it’s spinning-

  • If the noise gets louder, it’s a squealing noise
  • If the noise goes away, it’s a chirping noise

Is The Serpentine Belt Chirping?

A misaligned belt causes a chirping noise as it enters a pulley. In most cases, you can attribute the chirping sound to one of the following issues:

  • Pulley misalignment
  • Improper belt installation
  • Fluid contamination on the belt

Of course, you have to find out the reason behind the belt misalignment. Skip ahead to the last 3 sections to find out how you can troubleshoot this issue.

Is The Serpentine Belt Squealing?

When there’s a relative slip between the belt and the pulleys, a squealing sound occurs. The slipping can be the result of many different things, including:

  • Low belt tension
  • High accessory/idler drag
  • Seized accessory bearings
  • Fluid contamination on the belt

Read on to find out how you can troubleshoot this issue.

1. Misaligned Tensioner Or Pulley

Common noise(s): Chirping

A misaligned tensioner or pulley throws the serpentine belt’s alignment of whack. So to prevent this from happening again, you need to identify the part that’s misaligned. To troubleshoot this issue, thoroughly inspect the tensioner and all pulleys.

  1. If the serpentine belt is wobbling, you can try to identify the source of the wobble. This will give you a good idea of which part may have a misaligned pulley.
  2. Give the tensioner and pulleys a visual inspection. Make sure that all the pulleys and brackets are properly tightened to the mounting surfaces.
  3. If you have an automatic belt tensioner, make sure that:
    1. The pulley turns freely without binding or wobbling
    2. The tensioner arm moves smoothly through its entire range of motion

If you determine that a misaligned tensioner or pulley is the problem, replacing it should do the trick.

2. Worn Bearing In One Of The Accessories


Common noise(s): Chirping, squealing

This problem is more likely if you’re working on an older car. Bearings, of course, wear out over time. When this happens, they usually either partly seize or allow the pulley shaft to wobble. If the bearings partly seize, the belt slipping over the pulley will cause squealing. If the pulley shaft wobbles, this throws the belt alignment out of whack.

If you suspect that a worn bearing is the cause, here’s a neat old school mechanic trick to try:

  1. Find a long screwdriver.
  2. Put the metal end of the screwdriver on the part you think may have a bad pulley bearing. Be sure to touch only an area that’s not moving.
  3. Put your ear to the other end of the screwdriver and then listen.
    • If you hear a chirping or squealing noise, you’ve found the part with the bad bearing.

To remedy this issue, you can replace the accessory.

3. Mistake With The Belt Installation Or Tensioner Adjustment


Common noise(s): Chirping, squealing

It’s possible that the belt and all the parts are in good shape, but the belt wasn’t installed the right way. It’s also possible that the belt is too long.

The first thing you want to do is to look for the belt installation guide. It should be inside the engine bay (near the radiator) or on the hood. The guide will tell you which way the belt should be installed. Use it as a point of reference while inspecting the belt’s path. If you find that the belt’s path isn’t correct, you can reinstall it.If the belt’s path is correct, and if you’re still hearing noises, then the problem may be:

  • Fluid contamination on the belt (motor oil, power steering fluid, antifreeze, etc.)
  • Belt that’s too long
  • Loose belt tension

Let’s expand a bit on the last point. The problem may be as simple as the wrong tensioner adjustment. The tensioner on some cars has springs, so you don’t need to manually adjust it. If you have one of those, and if the adjustment is wrong, then it may be stuck. You can try using WD-40. If that doesn’t work, replace the belt tensioner. It’s possible that the spring has weakened.

If there’s a manual tensioner on the car, make sure that its tension is correct. The belt should have about half an inch of play for appropriate tightness. You should tension the belt during installation, and then re-tension it after 5 minutes of run-in.


Stay current!

Sign up here to get the latest news
and updates on all things GMB.

Sign Up To Receive GMB News & Updates!

  • This field is for validation purposes and should be left unchanged.