Most of the people when they hear a screeching noise after starting the car, they think, it will disappear after a few minutes. But the issue continues. In most cases, the noise gets even worse. The issue is with the serpentine belt, and it can make such squeaking noise for a few reasons.
You don't need to visit an auto repair shop and spend quite a few bucks on fixing it. Anyone with little knowledge about repairing small technical issues of cars, can easily stop the belt from squeaking.
In this repair guide, I’ll show you how to get rid of this problem without asking for professional help.
What is a Serpentine Belt?
Before understanding why serpentine belt makes such noise, let’s have some basic knowledge about what this belt is and what it does.
The belt is found in automotive engines part such as air conditioning compressor, air pump, alternator, water pump, power steering pump. It’s made of sturdy rubber material for required strength and durability to transfer energy from the engine to these important parts of a car.
This belt keeps your air conditioning, fan, water pump, power steering, and alternator working.
Many car engines use several belts to transfer energy to different parts. But modern cars these days, use a single serpentine belt to power all those engine accessories.
How Does a Serpentine Belt Work?
The belt transfers rotational energy from the engine crankshaft to important accessories like power steering pump and alternator by revolving around these accessories.
It transmits energy through different pulleys while curling like a snake. In addition, it also powers the crankshaft in order to control the pistons.
A serpentine belt either works with an idler pulley or a belt tensioner. They can be manual, spring loaded, or even hydraulic. The tensioner applies force to create tension for the belt. Serpentine belt, on the other hand, maintains proper tension so that you don't need to re-tighten it.
When the belt fails or breaks off, the components that depend on it will fail eventually and lead to other issues.
Why a Serpentine Belt Makes Noise?
There are various reasons why a serpentine belt makes squeaky noise inside the engine. Usually, if the rubber belt slips on the pulley, it starts to make such noises and gets worse by as time goes.
There are some factors that influence the belt to slip;
Wear and Tear
These rubber belts don’t last forever. Eventually, a belt develops wear and tear, reduces stiffness depending on how long it’s been running inside the engine. The surface also becomes brittle, cracked, and glazed.
This is the most common reason behind the noise. Make sure the belt is tensioned properly and re-tensioned after a couple of minutes when the engine starts.
Misaligned Pulley or Tensioner
The belt tends to slip and makes noise when it’s not aligned properly with the pulley system.
Due to the extreme weather, the belt reduces its stiffness and makes the squeaking noise.
Any kind of fluid leaking from different engine accessories, splashes on the belt which causes such disturbing noise.
How to Make Serpentine Belt Stop Squeaking
As I've said before, there are numbers of reasons why a serpentine belt makes squeaking noise. You need to try a method depending on the reason why the belt is acting so. Here are some methods to stop your belt from making such noise.
Method 1 – Apply Belt-Dressing
Before proceeding the process, ensure the serpentine belt of your car is made of neoprene. Otherwise, an EPDM made belt will dry out if you try this method.
You will obviously need to open the hood to apply belt dressing onto the belt directly. If your vehicle has any cowl cover or extra engine cover, remove them. Make sure you have clear sight of the belt line when the engine runs.
Now, be sure to park your car having engaged the parking brake, and then start the engine. While keeping the engine in running state, spay the belt dressing onto serpentine belt and back of the fan belt.
You don't need to move the spray around the belt; the running engine will spin it, and allow to spread the belt dressing to the entire belt. The squeaking sound should stop by now.
If the problem persists, head on to the other methods.
Method 2 – Tightening the Belt
Misalignment of the belt on pulleys is the most common reason why the noisy sound comes inside the hood. When the belt is not properly aligned, it will cause wearing out even faster.
Open the hood, and examine if the belt is mounted properly straight on top of the pulley. You can use a tape to measure if you are not sure whether the belt is straight or not.
While examining, if you find any sign of excessive damage on the belt, you have no option but replacing it. Modern EPDM belts last up to 100,000 miles, while on the other hand, it’s 30,000-60,000 miles for the neoprene belts.
Now, you need to locate the tensioner pulley, if your car has it. However, if you are not sure whether the car has a tensioner pulley or not, have a look at the service manual or search on the web. It's directly bolted to the engine block with a ½ inch opening for ratchet drive.
If you find the tensioner pulley is already worn, and it's not able to apply a sufficient amount of tension to the belt, consider replacing the tensioner pulley.
Remove the bolts of the tensioner that passes through the engine block, and bolt a new one. Now, align the pulley and properly tighten the bolt.
When you tighten the tensioner, the issue should be gone when you start the engine.
Method 3 – Replace the Belt
If you see too much wear and tear on the belt, and excessive damage, then consider replacing the belt. When you go to an auto parts store for purchasing a belt, they will ask you about the model and exact year of the vehicle, and the engine size.
Getting an EPDM belt is recommended as a replacement to the older one. Once you get the belt, compare the length and width of both the belts. The newer one should be exactly of the size of the older belt.
Now, to replace the belt, you will require a ½ inch ratchet drive to loosen the tensioner pulley. Twist it clockwise and bend tensioner arm down to get off the tension from the belt. Before removing the belt, be sure to note down how the belt runs through the engine.
However, if you don’t have any diagram, in this case, consider taking a picture of the old belt. Following the diagram or picture, install the belt through the pulleys. Make sure the belt is installed on each pulley evenly while creating a straight line. Otherwise, it will damage soon and make the squeaking noise again.
You can ensure whether the belt is installed correctly by going through the service manual of your vehicle.
Now, time for the final touch. To secure the belt, apply the tension to your newly placed belt. Take a look again to check whether the belt is straight or not. And, finally, start the engine and notice if there is any squeaking noise.
Other Possible Solutions
If the issue persists, here are some possible solutions to get rid of the problem;
- If you find the fan belt is cracked, missing any ribs, worn out from one side; then it's probably due to misalign the belt. It can also lead to a pulley issue. If the belt is damaged, there is no way but replacing it. Otherwise, the damaged belt can cause issues to the other parts of the engine as well.
- In case of any fluid leaking or water falling on the belt; it may be because of leaking coolant, motor oil, or other engine lubricating oil. In such cases, take the vehicle to a professional and let him take care of the issue for you.
- When pulleys have any worn spots and buildup deposits, recheck the alignment of your belt on pulleys. The belt needs to line up straight.
- Check the longest area of belt tension. If the amount is more than ½ inch, then consider tightening the tensioner properly.
When the serpentine belt under the hood makes noise, it’s not always necessary to replace it. There are ways to fix the issue depending on why the belt is making such noise.
However, if you have to get a replacement, make sure you properly align the belt onto the pulley to prevent further damage that can cause the issue again.