Alternator Whining Noise: How To Fix Bad Alternator Sound

If your car is making a whining noise and it’s coming from the engine, you could be dealing with a bad alternator. Though they make different noises, the alternator whine is the most common one.

Today, we will discuss the different kinds of alternator noise and we will also see what causes an alternator to go bad. Additionally, we will give you a short and easy guide on how to replace your alternator and save a pretty penny. 

As you may already know, your car has sensors and electronics all over the place, which need the power to function. But how does the battery keep all this running? Well, it doesn’t, that’s the alternator’s job. 

When the engine is on, the alternator generates electricity that doesn’t only power everything in the car, it also charges the battery at the same time. The role of the battery is to help start the car, but once that’s done, the alternator takes over. 

alternator whining noise

Signs of a Bad Alternator

To determine if your alternator is going bad, you have to keep an eye out for certain signs. Such as: 

The Headlights Are Flickering

If your headlights go brighter or dimmer as you increase or decrease your speed, that’s the first sign of an alternator issue. When the alternator is in good shape, it will keep the headlights steady no matter what your speed is.

So, if you notice that your headlights are changing with your speed or they are flickering quite often, it’s time to get your alternator checked out because it could die on you at any moment. 

The Battery Is Compromised

If your battery starts getting weak or dies on you, it means the alternator is in trouble. Remember, the alternator generates energy for the car’s electrical devices. If it stops working as it should, these devices will start drawing from the battery, effectively shortening its lifespan. 

You can tell the difference between a bad battery and a bad alternator by checking the battery gauge before you start the car. If you see it’s sending a strong charge, it means the battery is not the problem. 

The Car Is Making Weird Sounds

Alternators have many different moving parts and when it’s working properly, those parts are constantly spinning. If they start to break or start working ineffectively, it will cause weird sounds. 

For example, you could hear a grinding sound or whining sound, it depends on what’s going on in the alternator. Either way, weird sounds are not a good sign and you should check the alternator. 

The Car Doesn’t Start Smoothly

When your car doesn’t start smoothly and it takes you a few tries, it means your alternator is going bad. This could also be due to a weak battery, but you have to eliminate the possibility of a faulty alternator before you consider other possible causes. 

On average, alternators have outputs from 13 to 15 volts. If it’s not in good shape, the alternator can go below or above those levels. In that case, a warning light will go on, so don’t ignore it. 

The Car Is Having Electric Failures

When your alternator goes bad, your electric devices will start failing as well. Remember, this is the primary source of power, so you may have an issue with your locks, windshield wipers, windows, heat, and more. 

If you have your suspicions and you want to make sure, you can conduct home tests or take your car to a professional so they can test the alternator for you. 

Bad Alternator Noises to Be Aware of

  • Bad Alternator Whining Noise

A bad alternator whining noise is the most common and it’s a very high-pitched, annoying sound that will continue while the engine is running. The more you accelerate, the louder the alternator whine will be. How to fix it: 

Tighten or replace the alternator belt. The alternator or serpentine belt goes through several pulleys, so when the crank turns, the belt pulls the pulleys so they can spin. In time, the friction of spinning at such a high speed will cause the belt to wear and it will start whining. That means it’s time to check if it can be tightened or if it should be replaced altogether. 

  • Bad Alternator Grinding Noise

When you hear a loud grinding noise coming from the hood, it means your alternator is going bad. The grinding sound will get louder and louder the more you rev the engine. How to fix it:

Replace the alternator bearings. The alternator generates power thanks to a serpentine belt that spins the pulley at thousands of rotations per minute. The bearings allow the pulley to spin smoothly and do its job. Eventually, the bearings will get worn out and when they go bad, they will make a grinding noise to let you know that you need to replace them.

  • Bad Alternator Squeaking Noise

If your alternator is making a squeaking noise, you know it’s going bad. This sound is not as constant as the others, but it’s repetitive and high-pitched. The faster you go, the louder it will get. 

This squeaking noise can happen while the car is in motion, but it can also happen when you turn the alternator pulley by hand when the engine is switched off. 

Check the alternator bearings. If the alternator bearings are worn out and need replacing, they will make a squeaking or grinding noise. In that case, you have to check the bearings. If they feel rough and coarse to the touch, you can either replace them or replace the entire alternator, which is easier, faster, and cheaper. 

  • Bad Alternator Knocking Noise

If your alternator is making a knocking noise, it can be due to several reasons. Such as a broken belt that’s flapping around the compartment, a broken bearing that’s jostling inside, or a loose bolt that’s moving around in there. How to fix it: 

Replace broken parts. Whether it’s a broken alternator bearing or a broken belt, you have to retrieve the piece and replace the broken parts. A knocking noise means something broke off and it’s now spinning around, so get your alternator checked to see what the piece is and what needs to be replaced. 

Tighten alternator bolts. Cars vibrate a whole lot, so it’s very common for things to loosen up. If one of the bolts has loosened up, it will be moving around whenever the engine is on. So, you have to go in, retrieve it, and tighten it up to get rid of the knocking noise. 

Now that you can identify the symptoms of a bad alternator and you can recognize what each noise means, you can find solutions for the issues. The fix could be as easy as tightening something up or replacing a piece, but most of the time the entire alternator should be replaced. 

In case you’re experiencing lifter tick noisenoisy differential whine, bad wheel bearing sound, clunking noise, catalytic converter rattle we have got that covered too.

How to Check Your Alternator

Before you make any repairs, you have to make sure the alternator is the issue. To that effect, you should check the alternator. Since it’s at the top of the engine, you won’t have an issue accessing it. 

  • Test the Alternator

Now, the first thing you want to do is test the alternator to determine if it’s working. To do this, take your meter, set it to read DC voltage, and connect the leads to the battery terminals. If the battery is charged and in good condition, it should read 12.6 volts. 

When the engine is running and everything else is turned off, the reader should be between 14.2 and 14.7 volts. If it’s higher, the battery could overcharge, and if it’s lower, it means that the alternator is not able to meet the demands of the car. 

  • Check the Alternator Belt

After that, you want to check the condition of the alternator belt. Worn-out alternator belts cause noise, so they should be replaced. Check the belt and if the grooves are larger than they used to be, it means it’s time for a new one. 

Luckily, replacing an alternator belt is not difficult at all and you can do it yourself. All you need is a socket set and the right belt replacement for your car. Remember, each car is specific, so make sure you get a proper high-quality replacement. The one I suggest is Bando OEM Quality Serpentine Belt.

Take a picture of the belt set up before you get started because it can get a bit confusing and it can serve as a guide. The first thing you need to do is locate the tensioner pulley to turn the nut in the center of it with a socket wrench. Then, move the pulley to loosen the belt. 

Once you slip it off, you can install the new belt in the same way. Just wrap it around all the pulleys (except the tensioner pulley) in the right direction. Lastly, take the pulley out of the way with the socket wrench and slip the belt over it. If you need visual guidance, this video can help. 

  • Check the Alternator Bearing

If you’ve found that the alternator bearing is the issue and it needs replacement, this is something you can do on your own if you feel up to it. It’s a bit more time-consuming than replacing a belt or tightening a few bolts, but it can save you money. 

We do recommend you do your research and get familiar with the process if you plan on doing this on your own, though. You will have to take out the entire alternator for this, so disconnect the battery and remove the belt. Then, disconnect the wire harness and remove the bolts. 

Once you remove the alternator, put it on a work table and insert the socket of an impact wrench into the pulley to remove the large nut. Next, remove the bolts and screws on the backside of the alternator so you can remove the outer plate. 

You also need to remove the housing bolts and any other screws on the outside. The bearing will be snuggled in the housing, so it can be difficult to remove. You can hit the shaft to do that and then remove the large bearings using a hammer. Finally, replace the bearings and put the alternator back together. If you need visual help, this video will be useful. 

How to Replace a Bad Alternator

Replacing your alternator is the very last option. If nothing else has worked and you are still dealing with noise and other issues or if the alternator has died entirely, you have to get a new one. 

Paying someone to replace the alternator for you can be very expensive, but if you feel up for it, this is something you can do on your own. Alternator replacement can cost anywhere from $300 to $1,000 on parts and labour costs. 

Of course, this is just an estimate. The price may vary depending on what kind of car model you drive. You can also save money by getting a remanufactured alternator, which is a refurbished alternator that’s sold like new, and the replacement will cost you between $300 and $500.

However, if you replace the alternator yourself, you can save a lot of money. In that case, you only need to purchase an affordable alternator like this one, which costs far less than what mechanics will cost you for the new one. This is available at a wide range of prices based on the model and make. Make sure they fit your car. They can cost from $100 to $350 and you won’t have to spend so much on labour costs. 

If you want to do this yourself, we recommend you get familiar with the process and when you’re ready, gather your tools. You should have a socket and ratchet set, a wrench set, a belt tensioner tool, a memory saver if necessary, safety gear, and your new alternator. 

The memory saver is to back up the electronic data on your old alternator if the car requires it. If you need help, check the user manual of your vehicle to see how this is done. Once you do this, if applicable, you can get started. Just follow these steps: 

Step 1: Disconnect the Battery

The first thing you need to do is disconnect the battery. Whether there’s one cable or several cables on your alternator, make sure you unplug them all. If you don’t disconnect the battery, you’ll likely ground a live wire during the replacement process, which is not good at all. So, don’t skip this step!

Step 2: Unplug the Wires

Unplug all the wires from the back of the alternator. This process is very simple, but it’s a good idea to label the wires as you go so you can put them back in the right place when you’re installing the new alternator. 

Step 3: Remove the Alternator Belt

All projects have a step that’s a bit more challenging than the rest, and this is it for alternator replacement. Removing the alternator belt from the pulley can be tricky. You have to find the tensioner pulley and move it enough so the belt slips off. 

If your car has screw-type or rod-end-type tensioners, you have to turn the bolt or rod-end with a wrench or a socket so you can release the tension and take away the alternator belt. 

Step 4: Remove All Bolts

When the alternator belt is off, you have to remove the bolts that connect the alternator to the bracket so it can come right off. Congratulations! You’re done with the first half of the job. 

Step 5: Examine the New Alternator

Before you install it, examine your new alternator and make sure everything is as it should be. Take a moment to compare it to the old alternator so you can get familiar with the bolt holes and connection ports. Make sure everything matches. If it doesn’t, you have to go back to the store or return it and get the right alternator for your car. 

Step 6: Install the New Alternator

To install the new alternator, you just have to go through the steps in reverse. Put all the bolts back in, reinstall the belt and check the tension to make sure there’s half an inch of deflection, connect all the wires, and connect the battery. That’s it! 

Once the new alternator is in place, you should test it with a multimeter to make sure everything is in order. Check that the voltage output is as it should and then you’re ready to use your car. No more annoying noises or flickering lights. 

If you need a bit of visual guidance, this video on how to replace an alternator will come in handy. 

Frequently Asked Questions

Can you drive a car with a bad alternator?

Whether you’re on the road or you can get to a mechanic or do the repair yourself right away, you may wonder if you can drive on a bad alternator. Well, we don’t recommend it. 

A bad alternator may last several months or it may be dead the next time you start your car, but driving while you know it has issues will only mess with your battery. So, take care of the issue sooner rather than later. 

How long does it take to fix an alternator?

If you’re doing it on your own, replacing an alternator can last a couple of hours. However, it will depend on your knowledge of car mechanics and your agility. If you take it to a shop, you may have to leave the car there for a day, but the timing varies quite a bit. 

How long does it cost to fix an alternator?

Replacing an alternator belt can cost $100 to $200. The part will cost $25 to $80, and labor will cost $120 to $200. This is an estimate, of course, and the cost may vary depending on how long it takes to access the belt. 

If you need to replace the alternator bearings, can cost between $500 and $1,000 in total, including parts and labor. Replacing the entire alternator will cost you between $300 and $1,000, depending on your car. 

If you do the job yourself, you’ll save a lot on labor costs, which can range from $300 to $500 or even more. The alternator itself may cost you $130 to $250, but they can be found for cheaper if you consider remanufactured options, which are sold like new. 

Can a bad alternator cause the engine to shake?

Yes, a bad alternator can cause the engine to shake. In fact, this is a symptom to look out for. If you feel like the engine is shaking while you’re driving, you should get your alternator checked. 

Can a bad alternator kill the battery?

Absolutely. The alternator has a very important job; it generates the power that the electrical systems require to function. At the same time, it charges the battery. 

When the starts to fail or go bad, it can go one of two ways; it can overcharge or it can undercharge the battery. If the alternator overcharges the battery, it will damage it entirely and you’ll have to replace it along with the alternator. 

If the alternator undercharges the battery, it will be flat, which means it reduces the lifespan of the battery. Not to mention that if the alternator stops working properly, the electric systems will use the batter for power, making it weak and eventually killing it. 

Final Words on alternator whining noise

Your alternator has a super important task to perform, so the moment you hear a noise or you notice certain things are failing, such as the lights, you have to get your alternator checked. Remember, put your safety first and make sure your car is always in good shape to be on the road. 

We hope this guide can help you identify all the symptoms of a bad alternator so you can get it fixed or replaced as soon as possible. A bad alternator can die at any moment and the last thing you want is for that to happen in the middle of the road!

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