Alternators are one of the most important parts of a vehicle. The alternator works to push electricity throughout your vehicle and assists in keeping the battery charged so that you can keep driving. Unfortunately, alternators also go bad pretty frequently.
A bad alternator typically produces a deep grinding sound or sometimes a high-pitched whining noise. A bad alternator will also have other things associated with it, such as a dead battery or a burning smell. Some remedies include testing the alternator and replacing it if needed.
Alternators usually give some pretty clear signs that they are failing. You can perform multiple tests to help decide whether this is the case. Read on to discover what a bad alternator sounds like and what you can do to correct this issue.
Troubleshooting a Bad Alternator
If your alternator is beginning to fail, one of the first things you’ll notice is strange sounds beginning to come from under the hood. While we will discuss the sounds a failing alternator makes, it’s important to remember that vehicles often make strange sounds for various problems.
Alternator sounds can sound similar to other problems, so you should usually take these sounds and combine them with other signs of a bad alternator before diagnosing it as a problem.
1. High-Pitched Whining Noise
The most common sound you’ll hear when the alternator fails is a high-pitched whining noise. This noise is produced the voltage begins to jump between two places.
The alternator should move the electricity smoothly throughout the vehicle and into the battery. When there are breaks in this movement, it often results in the whining noise we commonly hear when an alternator fails.
2. Whining Noise When Accelerating
You’ll likely hear this noise more frequently when accelerating the vehicle. This is because the alternator typically charges the battery while the vehicle is in motion. You may also notice that the sound becomes more static, like when you accelerate. It may come and go and break frequently.
3. Low Grinding Sound
Another sound you may hear is a low grinding sound. Usually, this happens when the bearings have worn down. There are multiple reasons why this can happen, but most of the time, it’s due to an inefficient load on one of the belts.
4. Growling Sound
You may also experience a growling sound if the alternator is working extra hard to get power to the battery but failing to do so.
5. Other Noises and Possibilities
In general, you won’t hear any other noises if the alternator is the only problem. That said, if you’re hearing clunking or thumping in conjunction with some of the noises we’ve just discussed, there are two possibilities.
One possibility is that the alternator is going bad, but there’s another problem with the vehicle. This is the most probable possibility.
Another possibility, however, is that the alternator is completely fine, and the car is experiencing other issues. This is why it’s important to know the other signs of a failing alternator. With this in mind, let’s move on with some other ways that you can tell if your alternator is failing.
Additional Signs of a Failing Alternator
There are quite a few additional signs that your alternator is failing. Let’s take a look at a few of the most common that you may see below.
The Car Won’t Start or Has Trouble Starting
Battery problems and alternator problems go hand in hand. When the alternator has a problem, inevitably, the battery will fail too.
When the car doesn’t start, many people conclude that there’s an issue with the battery itself. After all, batteries need to be replaced frequently. However, almost as often, the battery is fine, and the alternator is the problem.
The best way to test this is to have your battery tested by a professional. If the battery is good, then you can move forward with the assumption that the alternator is likely failing.
The Car Is Giving Off Weird Smells
Cars generally smell odd, especially if you’re standing outside a running vehicle. However, some smells aren’t common unless your vehicle is experiencing a problem. One of these is a burning smell.
A burning smell, specifically the smell of burning rubber, is nearly always indicative of a serious problem in your vehicle. Sometimes it can indicate the vehicle is overheating, but most often, it’s an electrical problem.
Since your alternator runs on electricity, this is one of the most common culprits for a burning smell. As we discussed, the alternator sends electricity through the vehicle and back to the battery. Things end up burning when this electricity isn’t following the correct path.
Of course, not all burning smells indicate a problem with the alternator, so you should also look at some other signs.
The Battery Light or Other Engine Lights Come On
Your dashboard lights are some of the most helpful features on a vehicle. The dashboard lights let you know ahead of time that something is going wrong.
When the alternator is beginning to fail, you’ll likely notice that both the check engine and the battery lights come on. This is one of the clearest signs of a problem with the alternator.
When you see this sign in conjunction with others, it’s definitely best to get your alternator checked out.
The Car’s Lights Are Dim or Flickering
Dim and flickering lights usually indicate a battery that isn’t receiving enough power. While this can be a problem directly with the battery, it is often a problem with the alternator. As we discussed previously, the alternator isn’t charging the battery.
When you notice the car’s interior or exterior lights or dim or flickering, the best thing to do is to test your battery first. You can nearly always have the battery tested for free at any local automotive shop or mechanic.
This is a good way to figure out what you’re dealing with. The process of elimination is always part of the troubleshooting process when it comes to diagnosing car problems.
The Car’s Internal Accessories Aren’t Working Well
If you have power windows or other auto-controlled features, you will likely notice that they aren’t working quite well when the alternator fails.
The power locks and windows will stop responding or respond significantly slower than before. You may notice that the window rolls halfway up and then stops or that the locks stop working as things worsen with the alternator.
This happens because the alternator cannot send enough power to your vehicle to keep things like this going. Instead, all the power goes toward the battery, so the car continues running.
Now let’s look at what needs to happen if your alternator fails.
Remedies to a Failing Alternator
You’ve determined that the alternator is likely failing, so what now?
Replacing the Alternator
When an alternator goes bad, the only solution is typically to replace the alternator. This may need to come sooner or later, depending on the state of your alternator.
Progression of Alternator Problems
Often, alternators will start producing mild problems that worsen over time. The alternator may start by weakening the battery initially, but it may stop charging over time.
Cost of a New Alternator
You can expect to pay somewhere between $150 and $300 for a new alternator that works well. On top of this, you will have to pay for labor unless you install it yourself. Replacing the alternator on your own isn’t recommended unless you have prior experience doing major mechanical work on your vehicle.
Labor Costs for Alternator Replacement
Labor for replacing the alternator will typically cost another $300 to $400, bringing your total costs to somewhere between $450 and $800. This depends on your vehicle type, how easy it is for the mechanic to reach the alternator, and how much the alternator itself costs.
Testing the Alternator Voltage
If you aren’t sure that you want to replace your alternator just yet, but you think that it may be experiencing some problems, one of the best things you can do is test the voltage it’s putting out. This can be done with a voltmeter.
Using a Voltmeter to Test the Alternator
There are other ways to test the alternator, but I’ve found that using the voltmeter is the easiest and quickest way since it gives you a clear picture of what’s happening without too much additional work on your end.
Check out this helpful guide for more information on how to test your alternator with a voltmeter.
Final Thoughts
A bad alternator typically produced a high-pitched whining sound. This usually starts early on and will continue throughout the time that the alternator is failing.
Alternators fail in stages. Usually, the alternator will show signs of failing before it stops working. You may also notice strange smells, frequent dashboard lights, and a vehicle that isn’t starting regularly, even with jumps.
When the alternator fails, the only option is typically to replace it. If you want to check on your alternator before going for a replacement, the best way to do so is with a voltmeter.
If you like this article, be sure to check out my other one on how to reduce road noise.