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Summary
  • If you need to replace your vehicle’s alternator, there might be a few more parts you’ll want to replace as well.
  • We recommend replacing the serpentine belt, tensioner, and idler pulleys along with your alternator.
  • Replacing all these parts at the same time will save you money and time in the long run.

Your vehicle’s alternator does two things: It charges your vehicle’s battery while its engine is running while also providing electrical power to your vehicle’s other accessories. Issues with the alternator can easily lead to issues with these accessories and with your vehicle’s battery. If you need to change your alternator though, there might be a few more parts you’ll want to replace as well.

Parts To Replace Along With Your Alternator

While it isn’t strictly necessary to replace all the parts in this section when you replace your alternator, you might find that doing so will save you a lot of hassle down the line. Doing it all at once means you’ll have less to worry about in the future.

Battery / Battery Terminals

battery or battery terminals need cleaning or replacement
Check if your battery or battery terminals need cleaning or replacement. | Image Source: Richard McCuistian

While you may not need to replace the battery (have it checked), you might need to make sure the battery terminals are optimized by either cleaning or replacement.

Since you’ll need to remove the negative terminal while replacing the alternator anyway, go ahead and give the terminals and their posts a good cleaning. Make sure you check the alternator connections for compromised connectors or an oxidized charge post terminal lug. The point is to reduce resistance in all the connections to as near zero as possible.

Since you’ll need to remove the negative terminal while replacing the alternator anyway, go ahead and give the terminals and their posts a good cleaning.

– Richard McCuistian, ASE Certified Master Automobile Technician

Serpentine Belt

The serpentine belt attaches to the alternator, providing it and other parts of the engine with power. A new serpentine belt should last about 60,000 to 100,000 miles, but you shouldn’t wait for it to wear out before replacing it. The last thing you want is for the belt to slip, which can reduce alternator output.  Replace the belt along with your alternator even if it still looks new.

proper belt and pulley mating provides good traction and water shedding in the bottom of the pulley grooves
Proper belt and pulley mating provides good traction and water shedding in the bottom of the pulley grooves. | Image Source: Richard McCuistian
worn out belt will tend to hydroplane when wet and slip
A worn-out belt will tend to hydroplane when wet and slip. Notice pulley groove peaks making contact with the belt grooves. Poor traction. | Image Source: Richard McCuistian
cracked and worn belt
There are belt wear gauges you can use to compare your belt to a new one to determine wear. The belt in the photo is cracked and worn to the point that it needed replacement regardless. Some belts won’t look bad until you measure the wear with the tool. | Image Source: Richard McCuistian

Because alternators typically last around 160,000 miles (note that many alternators last a lot longer or just need brushes when they fail), it’s likely you’ll have to replace your serpentine belt a few times before replacing your alternator. That being said, if you’ve not replaced your serpentine belt at all before your alternator needs replacing, then you might as well change them together.

Tensioner

Your vehicle’s belt tensioner is there to keep the serpentine belt sufficiently tightened. This keeps it from slipping or providing insufficient power to the different parts under the vehicle’s hood, including the alternator.

It also keeps it from squealing and running hot. Your vehicle will usually have either a manual tensioner that can be adjusted with the turn of a bolt or a screw, or an automatic spring-loaded tensioner.

, Other Parts To Replace When Changing Your Alternator

Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.

Pro Tip: The belt tensioner has a bushing and a damper in the center of the arm that wears out that you can’t see, and when the tensioner needs replacing, it will bounce and cause the belt to make odd noises.

photo showing belt tensioner bushing and damper
Photo showing belt tensioner bushing and damper | Image Source: Richard McCuistian

Your mechanic might recommend replacing the tensioner along with your alternator for a relatively affordable price. Given how both types of tensioners wear down over time, it’ll likely be worth replacing it with your alternator.

Idler Pulleys

Idler pulleys are bolted on the engine and guide the serpentine belt around the rest of the pulleys for efficient routing. They’re relatively quick and easy to replace, taking only a few minutes to swap out. You’ll often find them packaged with a replacement serpentine belt and tensioners. Replacing all of these parts at once is often the best choice.

Now you know what parts to include when you change the alternator of your vehicle. Hopefully this saves you a bit of time and money in the long run.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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