There are several pulleys in front of your car. These pulleys are belt-driven components that function properly through a mechanical force distributed to them by the serpentine belt. When these pulleys or your drive belt goes bad, it generates squeaky noise.
If you hear a squealing or whirring noise in front of your car, whether the belt noise goes away when warm or not, it could be so annoying and embarrassing.
This squealing noise is mostly caused by a bad serpentine belt. It becomes more annoying if the alternator belt squeals after replacement.
In this piece of article, we will look at the causes of squealing serpentine belts after replacement and how to diagnose and fix the problems.
What is an Alternator Belt and What Does it Do?
An alternator belt, also known as a serpentine belt or drive belt, is a crucial component of the engine’s power transmission system.
It is responsible for transferring power generated by the engine’s crankshaft to the alternator, which then generates electricity to power the car’s electrical system and recharge the battery.
The alternator belt is typically made of durable rubber and reinforced with fibers or cords to withstand the high tension and stress of its operation.
It is looped around the crankshaft pulley and the alternator pulley, and sometimes other engine components, depending on the design of the engine.
When the engine is running, the crankshaft rotates, which in turn rotates the alternator pulley through the alternator belt.
This rotation generates an electrical current in the alternator’s coils, which is then converted into usable electricity for the car’s electrical system.
Because the alternator belt is such a critical component, any damage or wear can cause serious problems for the engine and the car’s electrical system.
This can manifest in a variety of symptoms, such as squealing or chirping noises, dimming headlights, or a dead battery. It is important to regularly inspect and replace the alternator belt as needed to prevent these issues and ensure the proper functioning of the car.
What Causes Alternator Belt Squeal after Replacement?
There are few reasons while your alternator belt gives whirring or whining noise even after replacement. Without further ado, let’s briefly look at the causes.
#1. Failing or Bad Hydraulic Belt Tensioner.
In some cars, the drive belt is tensioned with the help of a hydraulic belt tensioner. This kind of drive belt tensioner is controlled by a little shock absorber working just like a spring-loaded tensioner.
When this tensioner starts to fail, it causes the car belt to squeal when turning. Most times, the noise will be there when the engine is idling. A failing or bad Hydraulic belt tensioner’s symptoms are rattling noise or leaks on the tensioner and the belt.
This component can fail at any time; however, most of them last longer while some don’t.
If you notice noise after changing your alternator belt, you need to assess your hydraulic belt tensioner (if your car uses this type of tensioner). This type of belt tensioner is common with Toyota Corolla and Toyota matrix.
#2. Failing or Bad Spring-loaded Tensioner.
As the name indicates, it works with the help of a strong spring. The spring helps it to automatically adjust the drive belt while the engine is in motion. If the spring goes bad, it will cause the tensioner to play back and forth.
When this happens, it’s either your drive belt starts pulling off at intervals or your car starts giving a squealing noise. This belt tensioner is common with today’s vehicles.
#3. Failing Tensioner Bearing Or Idler Pulley.
In some cars, there are some rollers that are not holding anything when you remove your fan belt. These rollers are called tensioner bearing or idler pulley. These are mostly seen in vehicles that are driven with only one giant belt.
These bearings have a little bearing inside that ensures optimally spinning. If the little bearing fails, it will generate a squealing or whirring noise.
This kind of noise is hard to detect where it’s coming from since there are many belt-driven pulleys that make the same noise when they go bad.
To easily detect if the idler pulley is why the new serpentine belt squeals on startup, you have to get a stethoscope to diagnose where the squealing noise comes from.
Failing alternator bearing, steering pump, AC compressor bearing, and water pump generate similar noise. If thorough assessment proofs that the noise is coming from your idler pulley, just get new and replace it.
#4. Belt or Pulley Misalignment.
As you’ve known, there are several pulleys in your car that are connected through the help of a drive belt. Most of the components in your cars are belt-driven devices.
For instance, the alternator works optimally with the serpentine belt connecting it to the engine pulley, enabling the alternator to turn together with other belt-driven components in your car.
Belt or pulley misalignment is a common issue that causes changed serpentine belts to still squealing. Misalignment means that the grooves on your belt are not aligned with the ones on your pulley. It also tells that you shift the belt a bit in or out in one of the pulleys.
#5. Bad Belt.
As the serpentine belt’s primary aim is to transmit power from your engine pulley to other belt-driven components, if your belt goes bad or you replace a low-quality belt that does not have enough strength to carry all the pulleys along, it produces a whirring or squealing noise.
If you notice a squealing noise after replacing your alternator belt, chances are the new belt is either too tight, too loose or one of the outlined causes is in place.
How to Diagnose an Alternator Belt Squeal After a Replacement?
While trying to fix all the above problems is a good way to sort all issues related to your serpentine belt preemptively, you can make things simpler and more precise using the following troubleshooting steps.
- Turn off the engine inspect the belt. Ensure that it’s perfectly seated and all the grooves are well aligned.
- Turn on the engine, and with the belt squealing, spray it with some water or WD40. If the noise persists, the problem should be a bad pulley, tensioner, or driven component bearings. If it goes away, the belt is too tight, loose, or misaligned.
- Get the engine idle and inspect if the tensioner and pulleys are running straight and not sideways.
- Inspect individual pulleys to check if they have too much play. The pulleys can wiggle a bit, but too much play will throw the belt’s tension off, leading to unexpected slippage and the annoying squeal.
Stop the Alternator Belt From Squealing
Method 1: Stopping the serpentine squeal
Step 1: Raise the hood after starting your car. Then, using a flashlight, find the belt’s ribbed side where it will go under the pulley and spray enough WD-40 to cover the belt lightly. If you listen and look at the belt, you may be able to find the exact spot where the belt starts to squeal.
Step 2: Over spraying the belt can severely damage the belt and create slipping. You want enough WD-40 on there to remove the moisture causing the squeal.
Give the engine a few minutes to run, spray the rubber dressing lightly, and continue letting the engine run until the squeal is completely gone.
Step 3: If the squeal stops and restarts or never leaves, the belt is glazed and can no longer grip the pulleys. The only solution is to replace the belt.
Method 2: Adjusting the tensioner
Step 1: Loosen the pulley nut.
Step 2: Adjust the tensioner until you eliminate the squealing, so you won’t have to over-tighten the tensioner or calculate deflection mm’s.
Step 3: After the tensioner is adjusted, retighten the pulley nut.
Method 3: Use bar soap to fix a squeaky belt
This method is a temporary fix and not really effective.
Step 1: Make sure the engine is not running.
Step 2: Rub the soap on the parts of the belt you can see and reach.
Step 3: Give the soap a few minutes, then restart the car to make sure the squeal is gone.
Method 4: Defective pulley bearing replacement
Step 1: Use a ½-inch impact wrench, and remove the pulley bearing nut while holding the pulley bearing in place with a channel lock.
Step 2: Once the nut is off, remove the pulley bearing.
Step 3: Place the replacement pulley bearing in the alternator and replace the washer and nut on the pulley. Hand-tighten the nut.
Step 4: Tighten the nut snugly but do not overtighten. Check the manual for the vehicle-specific torque recommendations and tighten it to that spec.
Method 5: Using belt dressing for squealing
Step 1: Read the directions on the belt dressing (belt conditioner).
Step 2: While the car is running, lightly spray the belt dressing on each side of the serpentine belt.
Step 3: Listen for the squealing to stop. If the squealing restarts or does not disappear. Take the car to a mechanic.
How to Use a Ruler to Check a Belt’s Tension
Generally, your serpentine and aux belts need to be tight enough to transfer power but not too tight to pull pulleys off alignment. As such, many engines don’t have a tension gauge.
If your vehicle has a tension belt monitor, you can use its readings to establish when the belt is tight enough.
- Use a ruler to measure between the two furthest pulleys in the assembly and identify the midpoint.
- Pinch the belt between your fingers and move it back and forth.
- If it is tight enough, you should get half an inch of play in both directions.
- If you get more, you will have to tighten the belt.
- If you get less, the belt is too tight, loosen it.
While this is a standard for most vehicles, consult your user manual for specific instructions on how tight your serpentine belt should be. If the guidelines exist, they should override this generalization.
FAQs.
Q: What happens if the alternator belt is too loose?
If your alternator belt goes too loose while driving, this will cause series of issues to your car. Your alternator will not run properly thereby causing the alternator to have low charging and eventually stop charging.
If your car runs with a loose alternator belt for a long time, your car will shut down after draining your battery. Always ensure your alternator belt is well tight, not too tight, though, as this has its own effect.
Q: How do I stop my aux belt from squealing?
Do not be confused; an auxiliary belt is the same as a drive belt, alternator belt, and fan belt. The best way to stop a squealing aux belt is to first diagnose the cause of the noise and fix it.
A squealing aux bet could be caused by belt misalignment, bad belt, or bad pulleys. Just figure out where the noise is coming from and replace or repair it.
Q: Is it bad to drive with a squeaky belt?
It is recommended to replace or repair a squeaky belt once you notice a squealing noise. However, driving with a squeaky belt for the first few days of noticing the squealing noise may be safe.
Q: Can I put WD40 in a squeaky belt?
Yes, WD40 can be used to remove rust on the belt and pulley grooves. It is advisable to spray WD40 on your belt grooves, but you should be cautious not to saturate this lubricant on the belt. Too much WD40 on your belt will cause severe damage to the belt.
Final Words
Your alternator belt should be given adequate attention, as it helps for the optimal functioning of your engine system.
In all, your engine system will not function optimally without your alternator belt. If you notice squealing noise in your car any time, whether your alternator belt squeal after replacement or not, ensure you give it proper attention. The noise has to be stopped.