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

Alternator Making Noise

When it comes to car parts, there are few that get more attention than the alternator. The average mechanic gets asked about this part once a day and for good reason – it’s one of the most important components of your engine. Without an operational alternator, you will not be able to start your car or recharge any electronics in your vehicle. Although they may look intimidating, fixing this part is actually pretty simple if you know what you’re doing. Unfortunately, though, there are many people who attempt to fix their own vehicles without proper knowledge and end up causing even more damage by mistreating their cars with incorrect repairs. This happens more often than not, due to a lack of information available on the topic.

To avoid this common mistake, we’ve put together a list of answers to some of the most frequently asked questions about alternators in order to provide you with the knowledge that you need when tackling this type of repair. We will be going over how it works, why they make noise and what signs indicate that your alternator is in need of replacement. Let’s get started!

How Does an Alternator Work?

If you are interested in learning how an alternator works, then take a look at Figure A below:

How the charging system works | How a Car Works

Figure A – Basic Diagram Of An Alternator What you are looking at is called an “infinite bus” system; a self-charging electrical system that has been used in automobiles since the early 1900s. The process begins when a motor/generator is spun by an engine belt that offsets a stationary armature. As this happens, a group of carbon brushes make contact with slip rings and begin transferring energy from the rotating shaft to the alternator’s stator coil assembly.

In other words, this device acts as both a generator and a dynamo – producing voltage while also regulating it at the same time – hence its name: Alternating Current/Direct Current Generator or Alternator for short. This process continues until all of the vehicle’s power needs have been met or until you shut off your car entirely. If there is any excess energy left over once powering your vehicle, that power will then be redirected to the car’s battery for later use.

Why Do Alternators Make Noise?

If your vehicle is making unusual noises while it’s running, there is a good chance that your alternator needs some work done. Although there are several things that cause this type of sound, one of the most common culprits is called “bushing wear”. This occurs when the armature begins rubbing against its own commutator during normal operation. Since these two parts are in constant contact with each other due to the movement between them, they’re bound to show signs of wear over time – especially if you drive your car daily or use any accessories which put extra strain on your electrical components (such as an aftermarket radio or radar detector).

As you can see in Figure B below, this is the area on the alternator which typically causes problems:

Renewing alternator brushes | How a Car Works

Figure B – Common Area of Bushing Wear As these parts begin wearing down over time, they will create a metallic grinding sound that becomes noticeable while your engine is running. The noise itself sounds similar to nails against a chalkboard and tends to get worse as the days go on. Unfortunately, though, most people who drive vehicles equipped with this type of system are unaware of its existence prior to hearing the horrible noise themselves – thus making it even harder for them to diagnose the problem correctly. Eventually, this wear will become so bad that it will cause permanent damage to your belt tensioner at which point you’ll have no choice but to replace the alternator completely.

How Do You Know It’s Time To Replace Your Alternator?

When it comes time to replace your vehicle’s alternator, there are several things that you should look out for in order to know when to pull the trigger. To begin, you’ll want to check your car’s battery every so often in order to make sure that it is not slowly dying on you. If you find yourself having a hard time starting your vehicle or if it simply won’t turn over at all, then chances are good that your battery is low – thus making it even harder for your alternator to recharge properly. If this is the case with you, then take a look at Figure C below:

6 Common Bad Alternator Symptoms You Shouldn't Miss

Figure C – Battery Terminal Connection A good way to tell if your vehicle is having charging issues is by listening to your engine. As previously stated, an alternator makes noise when it’s not working properly – so you should be able to hear it pretty easily. You can also check each of your accessory’s amperage draw with a clamp-on DC voltmeter in order to see the difference before and after turning on additional components. With that said though, there are some cases where this isn’t always necessary.

If you’ve already ran into problems with starting or maintaining battery power for more than one day, then chances are good that you’ll need a replacement alternator. Although this type of system does not typically give out at once, the fact is that it will most likely fail on you at some point – so why not get a head start and replace it before that happens?

How Do You Know If You Have Bushing Wear? Although there are several tell-tale signs of bushing wear, this problem is often one which goes unnoticed by the untrained eye. To help explain this more clearly, lets look at Figure D below:

How to Test Alternator with Screwdriver At Home

Figure D – In order to test for bushing wear, simply press your fingers around the alternator as shown above Once you have located the part of your vehicle’s alternator which is being affected, use both hands to push down on each side of it as if you were squeezing a stress ball. By doing this you’ll be able to feel the play inside the part itself as shown in Figure D above. In most cases you will feel this right away, but depending on how bad your problem is – it may take a little bit of time before you’re able to tell.

Amazon.com: ACDelco 10495216 GM Original Equipment Alternator Bushing :  Automotive

Figure E – Here’s an example of a questionable bushing that would need further inspection If after pushing down on both sides of the alternator you cannot seem to notice any difference or if your fingers do not meet at all, then chances are high that you will probably need to replace it within the near future. This said though, these parts tend to give out very slowly so it’s hard to be entirely certain without doing some tests first.

Should You Replace Your Alternator Yourself? Diagnosing and replacing an alternator is a relatively easy task if you have the right tools and know-how – however, it does require some time and effort to do correctly. To help explain this more clearly, we will take a look at Figure F below:

Pros and Cons of OEM vs Aftermarket Replacement Parts | Haynes Manuals

Figure F – Here’s an example of what a new alternator typically looks like Although aftermarket parts tend to be cheaper than OEM ones, they are not always better in terms of quality. In most cases, you’ll want to replace your alternator with something that matches or exceeds your vehicle’s original equipment specifications as shown above for best results. This said though, there are some aftermarket models which work equally as well as OEM parts but simply do not last as long without failing.

Steps on How Do I Fix Alternator Making Noise?

1. The first step you should take in repairing your vehicle is to park it in a safe and secure location and turn the car off. When you lift up the hood, be sure that it’s also safe for you to work on by making sure there isn’t anyone or anything around your engine so they can’t get hurt when you attempt any repairs. Check for any safety precautions in your owner’s manual such as using jack stands before lifting up your car so you don’t accidentally damage something while doing this.

2. Next, locate the alternator belt and loosen it before removing it from its path of travel. There are typically hooks or bolts holding it onto the rest of your engine that will need to be removed and set safely to the side. Note that your owner’s manual can provide you with specific directions on how to access and remove your belt, but make sure you don’t put it back onto the pulleys or tensioner until you’ve completely finished working on it.

3. With the belt removed, inspect your alternator for any rust or corrosion that may be slowing down its functionality. These parts tend to work through grime buildup after time, interfering with their ability to hold power efficiently or charge current. You can usually use a wire brush or sandpaper to clear away these particles if they’re not deeply embedded into the metal itself so they can no longer affect its performance when put back in place.

4. At this point, you may be ready to test your new alternator by plugging it into your car’s battery with the engine turned off. Once you’ve safely connected the two, turn on your lights and accessories to see if the part is successfully charging your device. If they remain at their original level or lose power after a short period of time, then that means that there was something wrong with either the belt or alternator when you removed them so start over again from step one.

5. If everything works correctly in this last trial, try replacing your belt onto the pulleys before turning on your car to make sure it doesn’t slip or come loose during operation. When tightening or loosening screws for these purposes, always take care not to overdo it by using force. If you feel too much of resistance between the screwdriver or wrench and an object, then back up to your original spot before turning any further because you may risk stripping the part’s threads inside its housing if they’re already worn down from excessive use.

6. After everything has been set into place, start your car again and let it run for a few minutes while continuing to check on your alternator’s performance through the engine bay with all accessories put to use. If it seems like there’s still something wrong with the belt tension, putting up some white smoke around the area is often indicative of excess heat being produced so let it cool down before attempting anything else.  

7. Lastly, but most importantly, make sure you turn your car off and double-check to see if everything is still holding up correctly after all work has been completed. Determining whether or not your alternator belt is the right size for your engine and gets along well with your other parts can help save a lot of trouble later on by avoiding any additional problems that could arise from getting stuck in the road somewhere. Aftermarket belts will fit almost every part as long as they’re properly sized, but using them without knowing how much tension should be applied may cause damage to its pulleys as it slips across their surface during operation.  

Final Thoughts

There’s a lot to understand about how to replace an alternator belt with these steps, but it doesn’t have to be as hard as you may think. Just make sure you always take the right precautions when working under your car so nothing gets damaged from being moved around or dropped on the ground after it’s been loosened from its original position. Otherwise, replacing your alternator belt yourself can save you a lot of money in parts and labor costs if it needs to be done at a garage near you.

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