5 Reasons That Might Cause Alternator Belt Squeal After Replacement

Have you recently replaced your alternator belt and it’s making a squealing noise? That could be very frustrating indeed! The belt is responsible for pulling several pulleys located in front of the car engine. Wondering what is making your alternator belt squeal after replacement? There could be a couple of causes behind the squeaky noise from the alternator belt. 

In most cases, this is due to a bad serpentine belt. Other reasons include a faulty hydraulic belt tensioner, bad spring-loaded tensioner, faulty idler pulley, and misalignment of pulleys and the belt.

Top 5 Reasons Why Your Alternator Belt Squeals After Replacement

Given below are a couple of reasons why your alternator belt is emitting a squeaky or whirring sound even after replacement. 

1. Faulty Hydraulic Belt Tensioner

The drive belt is kept in position via a hydraulic belt tensioner in certain cars. The tensioner works like a spring-loaded tensioner and is controlled with a shock absorber. If this hydraulic belt tensioner starts to fail, the car alternator belt might start squealing, especially when you take turns. However, mostly the squeals will come when the car engine is in an idle state. This type of belt tensioner is often seen in Toyota Corolla and Toyota matrix. 

Car Belt Tensioner and pully

Solution: If the hydraulic belt tensioner is not working fine, is loose or too tight, then you need to inspect it to start with the repair. You need to be very careful while repairing or replacing the hydraulic belt tensioner, otherwise, you might end up causing serious damage to the engine. Here’s a video tutorial to help you fix the belt tensioner:

2. Faulty Spring-Loaded Tensioner

We’ve mentioned in the previous section that the spring-loaded tensioner works due to a strong spring. This is responsible for adjusting the alternator belt when the car is in motion. However, if the spring in the spring-loaded tensioner goes bad, which isn’t uncommon, the tensioner will start moving back and forth. If this happens, either the alternator belt will pull off periodically or you’ll get a squealing noise.

Timing Belt

Solution: If the spring-loaded tensioner has gone bad, then probably you need to replace the entire tensioner because the spring isn’t working fine. You need to make sure that the tension on the belt is just right, if it is too tight, then you need to loosen the belt tensioner and vice versa. Here’s how to adjust the tension in the spring-loaded tensioner:

3. Tensioner Bearing Or Idler Pulley Not Working Fine

In the case of certain cars, some rollers don’t hold anything when you have removed the fan belt. These are known as tensioner bearings. These also go by idler pullers and are mostly found in vehicles that have a single huge belt. The tensioner bearings then ensure that the belt spins appropriately. If the tiny bearings inside the idler pulleys fail, you can get a squealing or whirring sound. Such noise is not quite detectable and you might not be able to identify where it’s coming from.

Solution: If the idler pulley or tensioner bearing has failed, you need to replace it with a new one. The steps involved in this procedure are easy. Start by removing the belt to replace the idler pulley and then, reinstall the belt again.

4. Misalignment of Belt or Pulley

Your car has several pullers connected in place via a drive belt. More or less every part of your car is belt-driven. The alternator has a serpentine belt that connects it to an engine pulley. This allows the alternator to turn along with other belt-driven components. So, if the belt or pulley is misaligned, then the alternator belt might still be squealing even after replacement. What this means is that the belt grooves are not aligned properly with the pulley grooves.

Fixing misalignment of belt or pulley

Solution: To fix the misalignment of the belt and pulley first locate the tension adjustment bolt and loosen it. Now, pivot the pulley inwards to reduce tension (or outwards as per the situation). Then, reposition the belt and pivot the pulley outwards to ensure that the appropriate tension is offered. Once, you get the correct amount of tension, tighten your tension adjustment bolt.

5. Faulty Belt

If you replaced the alternator belt with a low-quality product, then it might not have the required strength to drive all the pulleys. As a result, some of the pulleys might get stuck somewhere, or perhaps the belt is making too much effort, this will produce a squealing or whirring sound. The newly replaced belt might be too loose or too tight, leading to this problem. 

Solution: If you have used a cheap and low-quality alternator serpentine belt that is unable to run properly in your car, then you need to replace it again with a good one. Here’s how to replace the alternator belt:

How To Diagnose And Fix Alternator Belt Squeal After Replacement?

To fix the problem, you need to first determine which component is causing the noise. Follow the steps given below to find the same:

Step 1. Turn off the engine and inspect the fan to check if the alternator belt is too tight, loose, or worn out. 

Step 2. While the engine is squealing, spray some water or WD40 on it and check if the noise is gone or not. If the squeal persists, the pulley or the tensioner is bad. Else, the belt and pulley have a misalignment.

Step 3. Now, examine the pulleys and the belt tensioner to check if they are running straight.
Then, inspect the drive belt properly when the engine is idle. Note if it is running sideways or straight.

Step 4. If you still can’t detect where exactly the squeaky noise is emerging from, then switch off the engine and remove the alternator belt. Now, inspect the belt for markings. If there are too many markings on it, then it indicates that the alternator belt needs to be replaced yet again.

Step 5. Check if the pulleys are playing too much to determine if they are bad or not. 
Once you have figured out what the problem is, simply replace or repair the component that was behind the issue. 

Final Thoughts

If you are irritated and embarrassed by the squeaky noise coming from the alternator belt after replacing it, then this article should have helped you to solve the issue at hand. The above content sheds light on all the common causes behind alternator belt squeal after replacement. Besides, it also provides various ways to fix these issues. Hopefully, this article has guided you to successfully get rid of the alternator belt squeal noise after replacement.

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