New Serpentine Belt Squeal: What Arises the Need?

A new serpentine belt squeal is required due to certain issues that go unnoticed in your car’s drive belt system. The issue could be from the pulleys, tensions, or even the belt itself.

New Serpentine Belt Squeal

This article will cover all the causes of this problem and show you step-by-step solutions.

Why Do New Serpentine Belts Squeal?

New Serpentine belts squeal because of faulty tensioners to damaged drive belts and pulleys. The problem could also arise due to failed bearings, drive belt misalignment, low weather temperatures, and exposure to liquids such as engine oil and antifreeze coming into contact with the belts.

  • Damaged or Faulty Tensioner

A damaged or faulty tensioner can be why your serpentine belt (also called drive or fan belt) squeals. The tensioner is a vital part of your engine’s drive belt system. It is a small component attached to the pulley that helps provide the right amount of tension for the belt to run freely. Tensioners, like any other car part, get worn out over time.

Some cars employ spring-loaded automatic tensioners, while others use hydraulic belt tensioners. Spring-loaded tensioners naturally weaken over time, thereby reducing tension and resulting in the slippage of your drive belt, which then causes a squealing sound.

The same thing happens with hydraulic tensioners (which contain oil in addition to springs). However, in this case, you’ll also notice hydraulic oil leaks and rattling noises besides the squealing sound.

  • Drive Belt or Pulley Misalignment

Drive belt or pulley misalignment can also be why your belt is squealing. The drive belt system is very delicate, especially because it operates at high tension. If the belt isn’t installed properly or gets misaligned due to slippage, the system may fail, even if the belt and pulleys are good. As a sign, you’ll hear loud noises.


Other times, it may be that the belt is mounted properly, but one or two pulleys are misaligned. Misaligned pulleys will not only affect the tension but also hinder the smooth running of the serpentine belt.

In any case, the most common sign you will notice when there is a misalignment in your belt system is serpentine belt noises like squealing or chirping. Note that a misaligned tensioner can also cause this noise.

  • Worn or Damaged Belt

A worn or damaged belt could be why your car makes loud squealing sounds while driving. The belt is crucial to activating several components in your car. Things like your AC system, alternator, power steering, and water pump system all depend on the smooth running of the drive belt. Modern-day belts are always long and drive several pulleys, transferring the power to their respective systems.

Damaged Drive Belts

Due to the fact that they are always operating under high tension and for prolonged hours, these belts don’t last very long. With time they suffer wear and tear (usually after about a 75,000-mile drive), and soon after, the belt breaks. A worn-out serpentine belt will produce squealing or rattling noises and may even snap.

  • Dry Belt

A dry belt can equally be responsible for the squealing sounds you hear while driving. The heat coming from your engine can affect your drive belt, causing it to dry out. The squealing sounds arise due to the excessive friction caused by the dryness. A dry drive belt will no longer be able to maintain the required tension to grip each tensioner pulley properly. Consequently, it may slip or even break.

  • Idle Pulley Problems

Idle pulley (also called idler pulley) problems can also make your drive belt emit strange noises like squealing and chirping. The idle pulley is a unique pulley in the drive belt system that provides clutching action, helps maintain the tension, and reduces slack in the engine belt. If the idle pulley fails or weakens, your car will produce annoying squealing or squeaking noises.

Aside from the idle pulley, if any of the other pulleys in the drive belt system are worn out, you’ll hear a squealing or chirping sound coming from your engine. Most times, the issue with the pulley lies in the grooves (the small space in which the belt fits). Pulley grooves get worn out over time and consequently damage drive belts.

  • Failed Bearings

Failed bearings could also be the reason why your new serpentine belt squeals. If your car is old, you’re likely to have a couple of pulley bearings that may have worn out over time, and sometimes, they also get stuck. Stuck or worn-out bearings cause the pulley to seize or wobble. A seized or wobbling pulley will ruin the drive belt alignment, resulting in loud squealing sounds.

  • Weather Temperatures

Low weather temperatures can also affect your drive belt and cause it to make uncomfortable noises. Extremely cold weather makes the belt brittle and ineffective, even if it’s a new one. This is why you may notice that your belt makes squealing sounds on very cold mornings but sounds just fine when the sun comes up or during warm weather. Generally, weather conditions affect the lifespan of the belts. If you live in very cold regions, your car’s belt will get damaged faster.

  • Exposure to Liquids

Exposing your serpentine belt to liquids like engine oil and antifreeze can also cause noises while driving. These liquids will only contaminate your drive belt when there is a leak under the hood. Antifreeze (also called engine coolant) is one of the most common liquids that cause this issue. Engine antifreeze is required to cool the engine during hot temperatures.
Your car pumps this liquid around the engine block to provide an even temperature to the engine. However, this coolant fluid can leak out when there is a hole or damage in the hoses circulating it.

Coolant leaks are highly destructive to drive belts, as they cause the belt to weaken or swell. As a side effect, your belt system starts to make squealing or whooshing noises. There’s no way to wash off antifreeze once it touches the belt. However, liquids like motor oil aren’t as serious in small quantities.

How To Prevent Your New Serpentine Belt From Squealing

To prevent your new serpentine belt from squealing, you have to realign the pulleys and tighten the drive belt or change the belt entirely. You may also need to replace the tensioner, change your pulley bearings, or fix engine oil or coolant leaks in your engine.

  • Pulley and Drive Belt Realignment

Realigning your pulley can fix your noise issue if misalignment is the cause of the problem. You can inspect your pulleys manually to see if any of them is out of place. For better precision, use a laser alignment tool.

Once you find the misaligned pulley, loosen and tighten it back properly. To loosen a pulley, insert a socket wrench into the hole at the center of the pulley and turn it clockwise. For some vehicles, however, you’ll have to loosen the bolts and then slide the pulley out.

  • Tighten Drive Belt

Tightening your belt can increase tension in the drive belt system and solve noise issues caused by slipping. To tighten your belt, you need to adjust the alternator or idle pulley. The easiest way to do this in most cars is to adjust the position of the alternator.

Prevent Belt From Squealing

First, start by loosening the bolts that attach the alternator to the bracket, but don’t remove them completely. Loosening the bolts frees the alternator so you can adjust its position.

Next, increase the tension on the belt by using a small piece of wood as a pry bar. This entails pulling at the drive belt until it appears tight over the alternator pulley. Finally, with your drive belt pried back and the alternator slid into a new position, tighten your alternator bolts in this new position with your free hand, or get a friend to tighten them for you while you hold the alternator and pry wood in place.

Once tightened, let go of your pry wood and check if the belt tension has increased. As a precaution, disconnect your battery before starting this procedure, and also be careful not to pierce or crush electrical connections or coolant lines while prying. Note that for cars with automatic tensioners pulley, you can simply adjust this to tighten your drive belt.

  • Change Drive Belt

Changing the drive belt when it’s worn out is the ideal solution. If your car uses an automatic belt tensioner, all you need to do is rotate the tensioner to free the belt. Next, simply remove the old belt and repeat the same steps to install the new belt.

For cars with manual tensioners on the alternator bracket, you have to loosen the bolts on the bracket and slide the alternator to reduce tension on the belt so you can get it off. Install the new belt and return/reinstall the alternator and bolts. Sometimes, a weak or worn-out tensioner may also be why you have a squealing belt. Replace such tensioners as well, or else they’ll ruin your new belt.

  • Fix Leaks

Fixing leaks or changing bad hoses will prevent engine coolant fluids or engine oil from coming into contact with your belt and ruining it. If you realize your belt is contaminated with any petroleum fluids, change the belt as well.

  • Change Bearings

Changing the bearings on a bad pulley can also stop the uncomfortable noises coming from your drive belt system. One way to know you have bad pulley/tensioner bearings is when the pulley fails to run freely through its entire range of motion or when it wobbles. Take off your belt and spin each pulley by hand to see which one has issues with its bearings.

Once you find the affected pulley, loosen it and pull it out. Next, get a socket and a vice and use these tools to press out the bearing from its hole in the pulley. Once you have it out, clean the pulley borehole and rub in some grease for lubrication before installing the new bearing.

Lubricating the bore before installing a new bearing is necessary to avoid unnecessary friction/resistance. Ensure that the bearing is centered properly in the pulley borehole. Finally, reinstall the pulley and test it.

  • Check Idle Pulley

The idle pulley is the tension pulley in the drive belt system, and it doesn’t last very long. If you’ve driven for 50,000-100,000 miles, you may want to check your car’s idle pulley as it may be responsible for the drive belt noises. Idle pulleys get worn out easily and consequently wear out the belt too.

If your idle pulley is bad, uninstall it and replace it with a new one. A new idle pulley may cost $40-$90. Ignoring a worn-out idle pulley can be very bad because, over time, the pulley may break apart bit by bit.

  • Belt Dressing

Dressing your belt is the simple and ideal solution for a dry belt. Spray a belt dresser on the belt to moisturize it and stop any squealing or howling noises. Ensure to spray the belt while your engine is running, which will ensure that every part of the belt gets moisturized. However, note that this process is only ideal for dry belts, not worn-out belts.


– What if Your Drive Belt Snaps While Driving?

If your drive belt snaps while driving, your water pump and alternator will stop working. As a result, your car won’t be able to circulate coolant throughout the engine to cool it off. Also, there’ll be no power to operate your vehicle’s electronic components or recharge your battery.

– Is Driving With a Squealing Drive Belt Safe?

No, driving with a squealing drive belt is not safe. The squealing sound is a sign that something is wrong with your drive belt system. Ignoring this sign may cause your belt to snap, leading to further complications like an overheated engine or a failed electronic system.

Faulty Serpentine Belt

Can a Clogged Exhaust Cause a Serpentine Belt to Squeal?

A clogged exhaust can potentially result in a serpentine belt squealing. However, it’s important to note that clearing a clogged exhaust precautions should be taken to avoid further damage. A clogged exhaust can lead to excessive backpressure, causing strain on the engine and belt system, resulting in the squealing noise. Regular maintenance and addressing exhaust issues promptly can help prevent belt problems.


Getting squealing or squeaking noises from inside your engine can be very uncomfortable and annoying. Thankfully, the problem is always from the drive belt system and can be resolved by changing or fixing some components.

Let’s go over the major points in this article one more time:

  • Bad or worn-out pulleys/tensioners, a worn-out drive belt, and misalignment usually cause squealing noises from your drive belt.
  • Other factors like failed bearings, a dry belt, cold weather, and exposure to engine liquids can also make your belt squeal.
  • To stop the squealing noise, change your drive belt, change bad pulleys/pulley bearings, tighten the belt, or realign the drive belt system.
  • Dressing your belt and fixing leaks in your engine can also help stop the issue.
  • Always look out for the service time of serpentine belts and idler pulleys (about 50,000 miles) and change them as a precautionary measure.

By following the steps outlined in this article, you will be able to fix the squealing or squeaking noises you hear from your engine.

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