Is Replacing an Alternator Hard? (5 Easy Steps)

Alternators are not a common part that needs replacing often as they are rated to last over 100,000-150,000 miles. But they can fail well before 80,000 miles. The failure of an alternator can be blamed on overuse, fault in wiring, fluid leak, etc. 

Having a non-functioning alternator means no power to your car electronics. Leaving no other choice but to replace. So, is replacing an alternator hard? Here are 5 easy steps to replace an alternator.  

Is Replacing an Alternator Hard?

Replacing an alternator is a rather simple task that can be done with a few tools. All you need is a wrench and socket set with some protective gear. It shouldn’t take more than 1 hour.

Alternators are a simple yet important component that is located towards the front of the engine. They are powered by the engine’s serpentine belt to produce electricity. Since alternators are located towards the front, they are easier to reach. They are also lightweight with a small form factor which makes them easier to remove.  

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How Long Does it Take to Replace an Alternator?

Replacing an Alternator can take between 45-60 mins depending on your efficiency. 

Alternators are located upfront on the top of the engine bay. They have vents on both sides with visible copper wire inside, making them recognizable. Where it gets complex with removing an alternator is properly disconnecting it.  

As the alternator is connected with both the engine and the batteries, you would need to disconnect both. Removing the engine serpentine belt gets a bit complex that requires you to find and loosen the tensioner pulley to slip the belt. This gets a little time-consuming. But with an hour on hand, even a novice can safely replace an Alternator.   

How Much Does an Alternator Cost?

The average price of a new alternator can range between $100-$350 depending on the car and the brand.

Alternators are simple, non-expensive components that run all your car electronics and also charge your batteries. So they have to be safe and efficient to produce the necessary electricity required. This is also the factor that affects the price of an alternator.

OEM alternators are designed as per manufacturer spec and are a perfect replacement. These alternators can go anywhere between $100-$400 depending on the car you drive. Even OEM spec aftermarket alternators go about the same price range with some high-end exceeding $400. 

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How Do I Know Which Alternator Will be Right for My Car?

The right alternator for your car will be one rated to your vehicle specification. Every manufacturer mentions the alternator amperage (output) on the fuse box cover or in the user manual. This will tell you exactly the amount of amperage needed to run your car electronics.

Any alternator OEM or aftermarket, rated at that amperage is the ideal replacement for your faulty alternator. 

The amperage can also be mentioned in volts, depending on the OEM origin. The whole point is to find an alternator with the same output or higher as the one you had. An average family car has alternators rated at 100 amperes while trucks and big vehicles use alternators at 200-350 amps.  

As the size of the alternator depends greatly on its output, an alternator of the same size or bigger would be enough to work as a replacement. 

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How Much Money Can You Save by Replacing an Alternator by Yourself?

Replacing an alternator by yourself can save you between $100-$300 depending on the size and placement of the alternator. 

Full-on alternator replacement goes for about $300-$400 for an average family car. If your alternator originally cost $100, you can save up to $200 by replacing it yourself. The same replacement can save extra if you drive a pick-up truck or a more powerful machine. 

This will also vary depending on where you get your replacement from, the type of car, and the complexity of the job. Overall, a mechanic shop is cheaper than a dealership. So replacing yourself as compared to getting it done at the dealership would save you a lot of money. But the same compared to a repair shop would save a little less. 

What Tools Do I Need to Replace an Alternator?

Replacing alternators need simple tools like wrench and socket sets with some protective gear. 

Alternator replacement doesn’t call for any special tool except a belt tensioner tool. All you need to do is remove a few wires and unscrew a few screws to get the alternator out and put in a new one. 

You can also use a ¼” 3/8 drive socket as an alternative to the belt tensioner tool. The tool is only needed to loosen the belt, which can be done with a socket wrench. Since Alternators are electronic devices, rubber gloves and shoes would provide good insulation.    

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How to Replace an Alternator in 5 Easy Steps?

Step 1: The very first step to removing an alternator is disconnecting it.

Before that, start by disconnecting the batteries. After the batteries, disconnect any/every wire connected to the alternator. You can mark them, so you know which goes where or take an image as well. 

Step 2: After disconnecting the batteries we loosen the serpentine belt.

All serpentine belts are held tight with a belt tensioner. Some of them are spring-loaded, while some use a screw or rod-type tensioners. You will have to loosen the tensioner pulley to take the belt off. 

Look for stickers around the belt to get information about the size and type of tensioner and socket size needed. After which you would have to loosen the bolt on the tensioner pulley to remove the belt. 

Step 3: Once the belt is removed, we remove the alternator.

Using a torque wrench, you can unscrew all the bolts holding the alternator. And then gently get your alternator out of the car. 

Step 4: Tighten the new alternator, securing it properly with the bolts.

After which, move on with the serpentine belt. Since the belt is already loose, you can slip it on the alternator and tighten the tensioner pulley.  

Step 5: Finally, reconnect all the wires and the batteries as they were.

Check for any loose connection before closing the hood. Put your keys in and start your car, leave for a few minutes and inspect if everything is working properly. 


What are the Signs of a Bad Alternator?

Alternators are responsible for running all vehicle electronics and charging the batteries. A bad or faulty alternator would cause electronic failures and battery discharge. A failing alternator commonly results in 

  • Failing car electronics
  • Discharged or dead batteries
  • Failed Ignition and regular stalling
  • Dim headlights
  • Whining noises or wire burning smells
  • Battery light On
Can a Bad Alternator Destroy a Car Battery?

A bad alternator can destroy a brand-new battery. 

A bad alternator means less charged or discharged batteries. If the batteries of your car are forced to provide electricity, it will soon get completely discharged as your alternator is malfunctioning. This will soon result in your battery dying due to lack of charge. 

Can You Drive with a Bad Alternator?

The answer is simply NO. No alternator means no electricity, no power for ignition, or no running any electronics.  

You cannot drive with a bad alternator, as it won’t be able to produce any power for your car electronics to work. The situation gets worse when your batteries die as well. Because then you have no power for the ignition, so you can’t start the car, and you would have to jump-start to get it going. 

Even if your batteries are charged, refrain from driving as it would kill the battery. In an emergency, a charged battery can get you going, but no alternator means no radio, no light, no AC, or any electrical device as it will chug all the juice from your batteries. And then you won’t have any power to restart your car if you get stalled.   

What Causes an Alternator to Fail?

An alternator can fail due to a host of reasons. While the most common cause is overuse of end of alternators lifespan at around 100,000 miles or above. 

Other factors that can fail an alternator are fluid leaks, dead batteries, losing its ground connection, and a worn-out/loose serpentine belt that is continuously slipping, not allowing the alternator to produce enough power. 

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