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The Cost To Rebuild an Alternator (And Is It Worth It?)

Having driven well over a million miles for work over the years, I have gone through my fair share of alternators. Replacement versus repair is a common question that I hear people asking. So today, I thought I’d talk a little bit about how it works for alternators.

On average, you will spend about $400–$650 to rebuild an alternator, depending on what parts of the alternator are damaged and how many parts should be removed to access the alternator. In many cases, replacing the alternator is cheaper than rebuilding the original one.

This article will discuss everything you need to know about rebuilding an alternator.

An alternator laying on a shelf

What Is the Cost of Rebuilding an Alternator?

Though most people assume their batteries are the hardest working elements in their cars, the alternator works harder than the battery. It supplies power to the car’s electrical components and keeps it running while concurrently recharging its battery. 

When this crucial part breaks down, you will conduct a thorough cost analysis of replacing vs. rebuilding it to keep your car going.

The typical hourly rate small garages charge for repairing an alternator is about $50, while dealerships will charge approximately $100. Along with this payment, you’ll have to pay for the diagnostics to confirm the alternator was causing the problems. 

Diagnostic tests will be $80–$120 though some places will charge more than this.

In most instances, repairing an alternator only needs cleaning its connecting points or getting a new belt. This means that the hourly labor rates at your garage or dealership will not amount to more than a few hundred dollars. The rates often include removing and disassembling your alternator, cleaning or replacing a few components, and then reassembling and reinstalling it.

What Is the Cost of Replacing an Alternator?

Though repairing an alternator might initially seem like the cheapest option in terms of labor, it’s often the more expensive choice. This is because it involves more steps compared to replacing the part. 

The average labor cost of replacing a car alternator is approximately $400 at a dealership and takes 2–3 hours. Alternator replacement generally includes taking out a faulty alternator, then replacing and testing it. 

The main cost of repairing your alternator is getting a new one. You can choose between a used OEM and an aftermarket alternator. On average, you can spend around $200 to $350 for an OEM alternator and $100 to $200 for an aftermarket one. 

Used car alternators might be cheaper than OEM and aftermarket ones, but they have no warranties. Since only faulty components have been replaced, you’ll often deal with a frequently broken-down alternator soon after replacing it.

When replacing an alternator, you might also need to replace the serpentine belt, battery, and plugs. The alternator’s operation is directly linked with these parts, so they will often be replaced together. The plug might have melted or degraded because of exposure to high temperatures, while the battery might be cranked if your alternator was not constantly topping up its power. 

Replacing these parts can add approximately $50–$150 to your cost.

You might be wondering whether your insurer can pay for an alternator replacement. Most alternators are destroyed from normal wear and tear. As such, insurers won’t pay for their replacement. However, most insurers will pay for a replacement if your alternator is destroyed in an accident, although this is rare.

Is It Cheaper To Rebuild an Alternator?

Car alternators have a lifespan of 80,000 to 120,000 miles (128,748 to 193,121 kilometers), spanning around seven years, though this also depends on the roads you drive on and how you drive. Although it can last much longer. The alternator on my Corolla lasted well over 300,000 miles.

Repairing the alternator is the better choice when it’s still relatively new. 

A mechanic working on an alternator

Remember that only the defective parts are worked on in rebuilding an alternator, so you might deal with new alternator issues later. This usually makes the cumulative costs of repairing alternators higher than replacing them.

Repairing the alternator of a high-end vehicle model might be cheaper than replacing it. The latest high-end cars often have a lot of newer expensive parts that require more skill and take more time to fix. This can quickly increase the costs, making a replacement the prudent option.

Can I Rebuild My Alternator Myself?

You can rebuild your alternator yourself and save the money you would have spent on getting a professional to repair it. Some vehicle manufacturers have alternator repair kits so you can repair yours without spending so much at the garage or dealership. 

Thankfully the procedure is relatively simple if you have some basic automotive knowledge. 

Here’s a step-by-step guide on a DIY alternator repair:

  1. Disconnect your battery leads.
  2. Remove the air cleaner to access the alternator.
  3. Remove the electrical leads after you have marked their placement points. You can take a picture of your phone to make things easier.
  4. Disconnect electrical leads.
  5. Remove the serpentine belt.
  6. After familiarizing yourself with the placement of the mounting bolts, remove them.
  7. Pull the alternator out.
  8. Unfasten the alternator’s plastic cover by unscrewing it.
  9. Inspect the bearing. If yours is not snug or makes noises when spinning, you might have to replace it.
  10. Loosen the screw holding the resistors.
  11. Carefully disconnect the wires paying close attention to their placement.
  12. Pry out soldered leads to replace the rectifier, then unfasten the mounting screws.
  13. Remove the rectifier.
  14. Replace the mounting screws to install a new rectifier and solder the lead wires.
  15. Reinstall the screws separating the brush assembly and rectifier.
  16. Remove the screw at the bottom of your brush assembly to remove the voltage regulator, then install a replacement regulator.
  17. Use a multimeter or ohmmeter to check that the diodes get the suitable current from your alternator.
  18. Replace the plastic cover and reconnect the alternator in your vehicle. Replace the electrical leads, serpentine belt, and battery leads, then verify that everything is working well.

Here’s a video detailing how to use one of the repair kits on the market to rebuild your alternator to ease your understanding of the steps above:

How Long Does It Take To Rebuild an Alternator?

Unfortunately, there’s no definite time frame for how long it will take to rebuild an alternator. There are many different alternators, and they take varying amounts of time to repair depending on how hard it is to remove them, clean their parts and reinstall them. 

It takes about 2–3 hours to rebuild an alternator. If you’re rebuilding it yourself, it will likely take more than 3 hours, whereas it’ll take less time for a professional to rebuild it. Additionally, the timeframe will also depend on your vehicle’s make and model.

How Do Alternators Work?

Alternators take over the battery’s responsibility to keep your car running by converting mechanical into electrical energy. A car’s crankshaft uses a serpentine belt to drive the alternator that, in turn, moves the rotor in an alternator at high speed. Electricity is generated as the rotor spins.

Magnets in the alternator allow the conversion of mechanical energy into electricity. The power then moves to a voltage regulator for distribution to different parts of your car. Before moving to the voltage regulator, power is sent to a diode rectifier that converts it into DC for your battery to absorb and recharge.

Signs That Your Alternator Has Issues

Unfortunately, identifying a failing alternator is not very straightforward because a vehicle’s battery might keep the engine running on its stored charge for some time after the alternator fails.

However, a failing alternator is quite a pain, so your vehicle will show signs that you need to repair or replace it. Here are some warning signs of a failing alternator:

  • If you notice that your new battery is dead soon after getting it, the issue might be with your alternator not charging it rather than the battery.
  • If a car’s engine suddenly stops when you are driving, this is probably an alternator issue since the engine stalls without enough power that an alternator should supply.
  • Failing alternators often cause voltage variations that make your headlights flicker or dim. Sometimes, you might notice that the headlights are dim when you leave the engine idling but brighten when the engine is fired up. This points to an undercharged alternator that will soon completely fail. In some vehicle models, a failing alternator highlights the Check Engine light on the dashboard.
  • If you notice a bad smell akin to burning plastic, this might mean your alternator’s internal components or wires are burnt. An acidic smell is often a sign of an overcharging alternator that can lead to a damaged, leaking battery.
  • Growling or whining sounds from under your hood might point to a misaligned serpentine belt that affects your alternator’s operation.
  • A cranking engine or clicking noises when you switch the engine on might also point to issues with your alternator.

Final Thoughts

From the information you have gleaned above, you now know how an alternator works and can identify the signs of a failing alternator. 

You can now make an informed choice on whether replacing the alternator or repairing it is the more cost-effective choice, and you could even save cash by repairing the alternator with a repair kit. Just remember that it’ll likely take you a lot more time to rebuild it than having a professional do it.

For more, check out Why Do My Dashboard Lights Dim When I Turn on My Headlights?

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