You know your alternator is vital to keep your car running. So when it shows signs of wear and tear or starts making unusual noises, you are only right to research to find out what the issue could be.
Generally, an alternator squeaks because of four car parts:
- Alternator Bearings
- Alternator Belt
- Alternator Belt Tensioners
- Alternator Belt Idler Pulley
Squeaking Alternator Bearings
The alternator bearings sit inside the alternator itself. As with all bearings, their purpose is to promote the smooth running of faster spinning belts or stators.
The inside of your alternator spins at many thousand RPM as your car is being driven. Over time they will start to fail, and when they do, they will cause a squeaking or squealing noise.
Alternator bearings are a repair if fail part and regular maintenance isn’t conducted on them.
Out of the four parts mentioned here, this is the most expensive in terms of labor to repair as it requires the alternator case to be opened and the bearing to be serviced.
The squeak is caused by the bearings drying out. The good news is once the alternator has been taken off the car and the case opened, the bearings are very cheap to replace. It’s the labor that costs money.
Squeaking Alternator Belt
I know this isn’t directly related to the alternator, but people often call the serpentine belt the alternator belt. This is because it powers the alternator as its leaves the crankshaft of the engine and snakes its way to the alternator and other systems under the hood.
As a general rule to check if the belt is worn, with the engine off, inspect the belt for signs of worn teeth on the inside of the belt and signs of brittle rubber.
If it doesn’t appear worn, it could be loose. Hold the belt between your forefinger and thumb and twist. If you can twist more than half an inch, your belt may need tightening.
As each car make will have a different tightness setting, it is difficult to specify exactly how tight the belt should be. Simply refer to the car’s manual to find out.
Most alternators can be stopped squeaking by loosening the bolts on the alternator tensioner and then using a pry bar to lift before tightening the belts again.
Squeaky Belt Tensioners
Almost all vehicles have an alternator belt tensioner. Its sole job is to maintain the tightness of the belt to prevent it from becoming loose and slipping.
There are two types one is hydraulic, and the other is spring-loaded.
In essence, they both do the same thing, and your car will have one type or the other.
You can normally find the tensioner between the engine crankshaft and the alternator pulley.
Squeaky Hydraulic Belt Tensioners
Hydraulic tensioners are normally found in high-performance vehicles where the alternator belt needs to produce more power. Such as V6 and V8 cars.
The tensioner looks like a small wheel that pushes down slightly on the bounce to keep it tight.
The tensioner has a pulley that can wear over time.
Also, the actuator inside can fail. Both cause a squeaking or squealing noise.
Squeaking Spring Loaded Tensioners
A spring-loaded tensioner works under the same principles as a hydraulic belt tensioner. Spring loaded tensioner is known as a mechanical tensioner. Therefore, these tensioners don’t have hydraulics or an actuator and are cheaper to replace.
They still have bearings, which are the parts that fail and start to squeak as they dry out.
Squealing Bearing on Idler Pulley
Normally the idler pulley makes a chirping or chattering noise when it goes bad, but sometimes a squeak or squeal noise occurs instead.
Most cars have one idler pulley on the alternator belt, which is not adjustable, whereas the belt tensioners’ sole purpose is to be adjusted to increase or decrease the tightness.
When the serpentine belt is taken off, alternator pulleys should spin freely without sticking and not create noise.
If you hear squeaking noises at the pulley, the bearing has gone bad because it is dried out.
Alternator pulleys can be repaired by taking out and replacing the bearings inside the runner. In truth, it’s just as easy and not that expensive to replace the pulley with a new one.
What Happens If An Alternator Squeak Is Ignored?
The squeaky noise you hear is a warning to take action and shouldn’t be ignored. It isn’t cost-effective to continue driving if you have any issues with the alternator. Not only can it be expensive to replace, but it can also let you down in the most inconvenient times.
Because alternator pulleys and tensioners are inexpensive, they should be replaced as soon as possible. These two parts can cause the belt to not run correctly to the alternator, putting additional strain on it.
Not only can this cause the alternator to fail, but it also means the alternator cannot power other parts of the car’s electrical systems properly when it is running.
You may encounter additional issues with your lights dimming, your air conditioning not working correctly, etc.
If you believe your alternator bearings are squeaking, you have a choice of whether to replace the entire alternator or the bearings.
The decision will be based on how much it costs to replace your car’s alternator as some are much more expensive than others, and the age of the alternator.
Alternators generally last between 7 to 10 years, so if your car is approaching this age and you are considering replacing the alternator bearing or the complete alternator, you may feel that it is time to replace the alternator in total rather than just the bearing.
Alternator belts are easy to replace. They are inexpensive, and you can probably do the job yourself with basic tools. I have included a video of this being done below.
Alternator Making A Whining Noise
Sometimes alternators make a whining noise rather than a squeaking or squealing noise. This is generally the sign of a different issue related to the voltage regulator, which is located inside the alternator itself in most cars but, on some older models, can be found separately away from the alternator.
The voltage regulator’s job is to regulate the voltage sent to the battery and other car electrical systems when the car is running.
If it fails, it can send too much voltage to these parts, and as it works harder to do this, you can make a whining noise. It can turn into a grinding noise when it is close to failing.
Hola noises are bad, but a whining alternator can cause more damage to other car parts than a squeaking noise.