Why Is My Alternator Making Noise and How Do I Fix It?

Unusual car noises usually indicate that something may be wrong with your car. Noises other than engine or exhaust noises should have you booking an appointment with a mechanic. A weird noise should also alert you to other signs of car failure.

When an alternator is making noise, such as a whining or grinding sound, it can often indicate a mechanical failure. A grinding noise typically signals a loose or worn-out bearing. On the other hand, a whining noise can mean that the alternator is charging more than necessary.

Read on to find out what different alternator noises mean, how you can fix a noisy alternator, and how long you should push a noisy alternator.

Do Alternators Make Noise When Going Bad?

Alternators make noise when going bad. A deteriorating alternator will likely produce a grinding or whining sound. By the time you hear the noise, you’ll probably have noted other symptoms of electrical failure.

The alternator provides power for the electrics of your car. It converts the rotating energy of the crankshaft to an electrical current that runs, among other things, headlights, the radio, seat heaters, and power windows.

Anything that needs an electric current to run, other than the starter, draws power from the alternator. Therefore, you run the risk of running out of power for essential functions if you fail to fix that noisy alternator.

Other Symptoms of a Malfunctioning Alternator

A malfunctioning alternator rarely throws up one symptom. The following signs, along with an unusual alternator noise, point to a degrading alternator:

Battery Warning Light

Your car’s onboard computer will be the first to signal that something is wrong with your car’s alternator.

Most cars built recently have an alternator warning light: ALT or GEN on your dashboard. The light shows when the alternator’s voltage is too high or too low.

In the initial stages of alternator decay, the light may come on for a few seconds before going off. The light switches on and off as the alternator struggles to meet the demands of your car’s electrical parts.

If you have a car without the ALT or GEN light, keep your eye on the battery warning light. It usually indicates that something is at fault with your car’s electrical system.

Blinking Headlights

Blinking headlights show that the alternator isn’t producing enough power to keep them at a constant brightness. In the early stages of the alternator’s degradation, the lights alternate between too bright or too dim.

Failure to remedy the problem will lead to a gradual dimming of the headlights. If the problem is the alternator, the dimming worsens when other electrical parts of the car are in use.

For instance, if the lights dim as you roll the power windows, it likely means that your alternator isn’t producing enough power.

Fortunately, modern cars have a failsafe installed that prioritizes essential parts such as headlights or wipers when the alternator produces insufficient power. Your car radio will stop before the headlights fail.

Nonetheless, take caution and visit a mechanic before you lose your headlights in the dark of night.

Malfunctioning Electrical Components

An alternator that’s going bad can’t produce enough power to keep your electrical systems running smoothly. You may notice that your window is rolling up too slowly, or your car radio cuts off at slow speeds.

Such anomalies usually point to an alternator that needs replacement or repair.

Hard Starts or Regular Stalling

Unless you have a terrible battery or left your radio on overnight, your car should start in the morning. That’s unless you have a lousy alternator.

The alternator charges your battery so it can have enough juice to crank your car’s motor in the morning. You will hear a clicking sound rather than the sound of your engine if you try to start your vehicle with a powerless battery.

To diagnose whether the problem is the battery or the alternator, jump-start the car and quickly remove the jumper cables. If you have a faulty alternator, the motor will die.

If the problem is the battery, the motor will keep working.

Failure to repair your alternator quickly will degrade your battery faster. Typically, the battery acts as a capacitor that stores power to start your car.

When the alternator starts failing, the battery uses its power to compensate for the alternator’s insufficient output. It will wear your battery out faster than if you had a working alternator.

Strange Electrical Fire Smell

An electrical fire smell may emanate from your alternator when it overworks itself. Such an alternator will produce too much current, thus overheating your engine’s cables. This smell is characterized by the smell of burning plastic with an overlay of thunderstorm ozone.

To sum up, a noisy alternator is most likely a troubled alternator that needs urgent attention. Keep your senses peeled for other signs that may indicate alternator trouble. If you notice that your car has multiple symptoms of alternator failure, get it checked out immediately.

Why Your Alternator Is Making a Whining Noise

Most people report a whining noise coming from under the hood before the car’s alternator goes bust.

The whining noise arises if the crankshaft pulley and serpentine belt misaligned.

The crankshaft pulley turns the belt that drives the alternator. The alternator’s pulley is smaller, so it spins faster than the crankshaft pulley to remain effective at slow speeds.

If the belt misaligns, it rubs against the pulley, producing a whining sound.

The belt continually rubs against the pulley, and since it’s made out of rubber, it will wear out. When it wears out enough, it will start sliding and rubbing on the pulley rather than spinning it.

Bent pulley flanges can also cause misalignment, and consequently, a whining noise.

The whining can also be a symptom of worn belt tensioners. Modern vehicles come with belt tensioners that adjust the serpentine belt’s tension.

In older cars, you must adjust the belt’s tension manually. Malfunctioning belt tensioners can loosen the belt leading to misalignment or, worse yet, the belt sliding off its pulleys.

An overworking alternator can also produce a whining sound. An alternator overworks when the voltage regulator instructs the alternator to produce more voltage than is required.

Reasons Your Alternator Is Making a Grinding Noise

Grinding noises from a malfunctioning alternator usually point to a bearing fault.

Worn-out or damaged pulley bearings might be the reason behind the grinding noise. A simple pulley replacement will solve that issue.

Damaged or worn internal rotor bearings will also produce a grinding sound when spinning. These needle bearings allow the rotor to turn freely.

They usually break down due to excessive heat or dirt. It is advisable to replace these bearings as soon as you hear the distinctive grinding noise from the alternator.

If you allow it to get worse, the bearings will fail and seize your alternator. It won’t be long before you park up on the side of the road due to a seized alternator.

Damaged bearings can also cause engine damage, so you should fix that damaged alternator as quickly as possible.

A less serious reason behind the grinding noise coming from your alternator is a loose alternator bolt. The alternator might be improperly mounted, thus causing noise when it vibrates with the engine.

How to Fix a Noisy Alternator

If you hear noises coming from your alternator, you can instruct a mechanic to resolve the issue for you. However, the repair might cost you a pretty penny. Alternator repair work doesn’t require much skill and is something you can do with the proper equipment.

To fix a noisy alternator, you’ll need to tighten the bolts around it. If this doesn’t work, you’ll likely have to replace any worn-out belts or bearings. If the noise persists, then it’s usually best to invest in a new alternator.

Let’s look at how you can fix a noisy alternator in more detail:

Tighten Bolts Around the Alternator

Before doing anything, make sure that the car engine is off. If the engine is running, give it some time to cool off.

Start by simply tightening the bolts around the alternator. If the reason behind the noise is a loose bolt, your work will be done.

Replace Worn-Out Belts

A simple check will reveal whether your belt is worn out or not. If you observe cracking, excessive wear, or any other symptom of aging, replace your belt.

Before removing the belt, take a photo of how the belt fits for reference when installing the new one. It’s relatively easy to remove the worn-out belt: Turn the nut on the tensioner pulley to ease the belt’s tension and slide the belt off.

Make sure you have the correct serpentine belt for your car. Before you replace the belt, try to rotate the alternator.

If the bearings make a noise or are rough, you need to replace the bearings before the belt. Otherwise, a new belt won’t solve your alternator.

If the bearings run as smooth as they should, proceed to install the belt.

Installing happens opposite to removal. Use the photo you took as a guide and wrap the belt around the pulleys.

Finish by sliding the belt onto the tensioner pulley and tying the pulley nut as necessary.

Replace Worn-Out Bearings

If the bearings produce a noise when you turn them, it means that they need urgent replacing.

You need to remove the entire alternator first. Disconnect the battery, remove the belt, and remove the alternator by loosening the bolts holding it in place.

Disassemble the alternator to uncover the bearing assembly. Remove the worn-out bearings from the bearing assembly and install the new ones.

Reassemble the alternator and fix it back in place.

The process might take you an hour or more, but the time lost can’t compare to the money you might lose to a mechanic.

Replace the Alternator

Sometimes, replacing individual parts like bearings and belts won’t silence the noise coming from the alternator.

If the noise persists, consider replacing the entire alternator.

Dislodge the alternator from its position by removing the bolts that hold it in place.

Install the new alternator by tightening the bolts. Also, remember to attach the wire harness at the back.

You can repair a noisy alternator from your home. However, if you lack the right equipment or aren’t confident about your mechanical abilities, have a mechanic do the work for you.

How Long Will a Noisy Alternator Last?

Haven’t got time to repair your alternator or money to replace it and still need to use your car? You are probably wondering how far you can push your alternator before it gives in. Driving with a noisy alternator is risky, but you can get lucky.

A noisy alternator can last for several months if the problem is not serious. If the problem is serious, you might pull on the side of the road with a powerless car the next time you start a journey with the faulty alternator.

Fix your alternator as soon as you hear it producing an unusual noise. A degrading alternator can seize at any time, which can cause a significant inconvenience.

Furthermore, a faulty alternator can destroy other parts of your car. It stresses your battery, thus reducing the battery’s lifespan.

Lose bearings can also cause expensive engine damage.

If your alternator problem isn’t serious, the alternator can last for several months while producing a noise. However, I advise that you treat the problem immediately. A minor issue can cause more extensive and expensive damage if you let the issue fester.

In Conclusion

A noisy alternator usually indicates that there’s a problem with your indicator.

After noticing the noisy alternator, keep your eye out for other signs of decreasing or inconsistent power.

The most common alternator noises are whining and grinding. Both indicate that there’s a problem with the alternator.

Resist the temptation to keep driving with a noisy alternator. You risk experiencing an inconvenient stall or aggravating a minor issue.

You can repair a faulty alternator with the right tools. Otherwise, visit your mechanic for a quick and safe repair.

See also: Do Car Batteries Charge While Idling?

Scroll to Top