Alternator Belt Squeal After Replacement

An Alternator Belt Squeal After Replacement is a loud, high-pitched squeal that can be heard coming from the engine compartment. This issue often occurs immediately after an Alternator Belt has been replaced, but it may also occur without any other alternator belt problems.

The first issue could be that the belt begins to squeal or whirr when warm and that the pressure levels do not return to normal even after several minutes. These are typically caused by either: A suspect pulley Or an overheated serpentine belt that has lost tension distribution due to poor quality rubber components attached along its length between motor/belt shaft assembly(s).

A serpentine belt can cause quite the hissing sound. If you’re noticing that your car’s engine is making more of an annoying squealing noise than it used to before, then chances are one or both belts have gone bad and need replacing! In this article, we will look into what causes them in the first place, as well as offer some tips for diagnosis if something sounds wrong with either setup.

Alternator Belt Squeal

What Causes Alternator Belt Squeal After Replacement?

Causes of Alternator Belt Squeal After Replacement include worn parts in the Alternators and pulleys, misaligned belts, poor sealing of bearings or pulley surfaces, loose bolts on bearing caps or tensioners, defective bearings, and binding between gears. Following are the more reason for What Causes Alternator Belt Squeal After Replacement:

  1. Bad Hydraulic Belt Tensioner
  2. Bad Spring Loaded Tensioner
  3. Failing Tensioner Bearing
  4. Pulley Misalignment
  5. Bad Belt

Let’s explain them one by one to know better about them.

Bad Hydraulic Belt Tensioner

When a hydraulic belt tensioner starts to fail, it causes the car’s belts and pulleys to make noise when turning. The symptoms may include leaks or rattling on both of these components as well.

You may have replaced your belt, but you should still check for other problems. If the noise is coming from a hydraulic tensioner and it’s been installed on cars made by Toyota Corolla or Matrix, then that’s likely what needs to be fixed too!

Bad Spring Loaded Tensioner

The tensioner is a vital component of your car’s drive belt system. It works with the help of an elastic spring which helps it automatically adjust while in motion, but if this engineering marvel goes bad, then you’ll have trouble. Either something starts pulling off at intervals, or there are strange noises coming from underneath where everything should operate smoothly!

Failing Tensioner Bearing

In some cars, there is a roller that holds onto your fan belt when you remove the tensioner. This bearing is most often seen in vehicles driven with only one giant belt and can cause noise because it’s little inside. It makes sure to spin optimally, but if this part fails, they will make a Squealing or Whirring Sound, which may be hard for someone outside your car to hear since most belts produce these same types of noises; from bad bearings too!

To easily find the source of your new serpentine belt squealing on startup, just get a stethoscope and listen for it. If you hear noise coming from anywhere else in the car besides that idler pulley, then there’s only one place left to look.

Your alternator bearing can also make noises like a steering pump or AC compressor when they fail too! ‍But if everything checks out ok with this? Replace both belts together because who doesn’t want their engine bay looking fresh again while driving down scenic highways?

Pulley Misalignment

Most of the components in your car are belt-driven devices. Alternators work best when they are connected to the engine pulley by a serpentine belt, enabling these two parts to turn together as other belts driving other important aspects within a vehicle such as air conditioning or heating system work smoothly without any problems whatsoever!

The common issue of pulley alignment is a very serious problem that causes serpentine belts to still be noisy and create tension on your engine. Pulley misalignment can occur in either direction, so if you see any shifting from side-to-side or up towards the center.

Then this could mean there’s an imbalance between how far across each groove has been carved out for its matching tooth pattern with one another as well as whether they’re all lined up perfectly straight downward, pointing at their respective pulley wheel(s).

Bad Belt

Belts always make a whining or squealing noise when they’re running smoothly. If you notice this in your car, then there is most likely something wrong with the belt, and it should be replaced immediately!

The serpentine belt’s main purpose is to transmit power from one place on an engine’s pulley wheeling systems-to other components powered by belts such as starters motors which create rotation using air pressure.

If these go bad due to either fatigue caused over time (loose), too much force being put onto them through collisions, etc., it produces unwanted sound but could also mean that we need our alternate output of power and force to be directed elsewhere.

This makes them so frustrating when one goes bad: the serpentine belt is usually connected directly to the engine’s power source, which transfers its energy down to other belts responsible for powering different systems.

How To Fix a Squeaky Alternator Belt?

A squeaky noise coming from your belt is never fun. It can be caused by bad bearings, tensioners, and even pulley misalignments; finding out where it comes from will require some patience when diagnosing, but don’t worry, we got this!

For starters, you should have everything ready before starting, so grab a flashlight or headlamp if needed, 2 x 10mm socket wrenches (or hex keys), A flat-head screwdriver/picker tool, And a stethoscope or mechanic’s stethoscope.

As you prepare to get started, just remember that the main source of noise is your alternator belt squealing. Start by removing the serpentine belt, and then take a look at where it sits as well as what direction it goes.

If the belt fits snugly and evenly, without any gaps or areas of slipping, then no adjustments need to be made as it’s good to go! However, if you notice that there is a lot of slack in your belts, which means we should adjust the tensioner pulleys to tighten up the belt.

It’s important that you don’t over-tighten your belts, as this can cause damage to their bearings and pulleys, which will lead us nowhere!

So let’s begin with our first step of tightening your alternator pulley tensioner by removing its mounting bolt or nut located on top of the alternator.

For this, we will need a wrench or socket and ratchet so you can loosen the bolts attached to the pulley itself, as well as the mounting bracket holding it in place.

Next up is our belt tensioner for adjusting your belts’ backside, where they connect to the engine’s crankshaft/crank pulley.

Remove the pulley’s mounting bolt or nut using a wrench to loosen, which is usually located beneath your vehicle, and behind your engine block close to where the belts are attached.

Now that you have loosened up all four of our tensioner adjusters on both sides of our belt(s), it’s time for us to tighten them back up by pushing the belt(s) into place towards your engine until it’s firmly pressed against its pulleys.

After you have finished tightening both tensioner adjusters, reattach your belts and then try to start up your car again in order for us to see if our job was done! If so, check your belts for any abnormal noises or squealing, and if none exist, then you’re good to go!

If the noise still exists, try loosening up your tensioner adjusters just a bit by turning them in small increments until they are no longer making that squeaking sound. If not, then there might be an issue with your belt(s) that needs to be inspected by a professional.

When they go bad, your belt may slip or squeal even at low speeds, which can cause decreased horsepower and might lead you to have problems with your engine overheating if not taken care of immediately!


If you’ve recently replaced your alternator belt, and the squealing is still happening, there might be a few other reasons for it. First, check to ensure that all bolts are tight on both ends of the belt tensioner pulley assembly.

Second, if your car has an automatic transmission or air conditioning, these can contribute to excess wear on belts by putting stress on them as they move around in their grooves.

Finally, have someone inspect under the hood who knows what they’re doing to see if any hoses could need replacement or tightening up. That’s all we have on Alternator Belt Squeal After Replacement.

Frequently Asked Questions

How do I stop my alternator belt from squeaking?

You can use WD-40 to stop your noisy car engine from squealing! Spray it onto each belt rib twice and allow them time in letting those fumes seep into every crevice between inner layers; then run as normal until satisfied with no more noise coming out at higher RPMs.

What happens if the alternator belt is too loose?

If the tightness of the belt is too loose, your car will stop for no reason.

Why is my new alternator squealing?

The most common cause is voltage regulator removal. It’s also possible that the belt has slipped off its pulley or that there are loose connections to battery cables.
However, squealing alternators are usually a clear-cut case of loose connections. In this situation, check the post and hole on top of the alternator for dirt, debris, etc., and clean thoroughly with WD 40 or similar lube.

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