Can You Replace Your Car’s Alternator Yourself?

I’ll be the first to admit wariness whenever electrical car repair or maintenance tasks come up. After the fiasco with my first car’s spark plugs and some later battery mishaps, I approach the sparky bits with extreme caution. However, some electrical tasks are as much about nuts and bolts as wiring. And trying to replace your car’s alternator is one of them. But is this something you can do yourself, or should you leave it to the pros?

How hard is it to replace an alternator?

Several teenaged technical school students replace the alternator in a diesel pickup truck
Technical school students replace the alternator in a diesel pickup truck | Kathryn Scott/The Denver Post via Getty Images

Before you start trying to replace your alternator, first make sure that it’s really gone bad. It’s possible that the serpentine belt that drives it slipped off or is either over- or under-tightened. Furthermore, some electrical issues, including trouble starting, stem from the battery, rather than the alternator. And while it’s definitely possible to improperly install a battery—ask me how I know—it’s not a wrenching-heavy process.

However, if your car’s alternator is indeed bad, you can try to replace it yourself. On paper, it’s a relatively straightforward procedure, The Drive says. But that also depends on what car you have and how tight its engine bay is. Also, on how comfortable you are with changing serpentine/accessory belts.

How to replace your car’s alternator

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The first step in replacing your car’s alternator is assembling your tools. Fortunately, this doesn’t require anything too complicated or expensive. All you need is a few wrenches and sockets, your owner’s manual, some eye and hand protection, and a replacement alternator. If your serpentine belt is rather new, you don’t have to replace it. However, it’s not a bad idea to swap out the old belt anyway, The Drive reports.

Next, figure out where your car’s alternator is; consult the manual if you need to. Depending on where it is, raising the car on jack stands might be unnecessary. Regardless, because this repair involves the electrical system, disconnect the battery’s negative terminal.

With that done, loosen up the serpentine belt tensioner near the alternator and remove the belt. Next, disconnect any wiring harness and brackets attached to it. Finally, remove the old alternator and install the new one. Then, just reinstall everything else, re-tighten the belt tensioner, and you’re all set.

Now, your car’s specific alternator replacement procedure might have some extra steps. With some BMWs, for example, you also need to remove the airbox and some ducts, FCP Euro notes. However, the basic steps are the same: get the belt off the alternator, swap it out, and put the belt back on.

Should you buy a new replacement car alternator or get the old one rebuilt?

A mechanic disassembling a car alternator by hand in his workshop
A mechanic disassembling a car alternator | Susan L. Angstadt/MediaNews Group/Reading Eagle via Getty Images

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Prices vary between car makes and models, but the average replacement alternator is rarely hugely expensive. Budget around $300-$500 for a new one, The Drive says. Or rather, budget $300-$500 for a remanufactured one, because that’s what most replacement units are. However, while their external casings might be old, the internal parts are new or like-new. And yes, brand-new alternators are available, too.

But this brings up an important point. Rather than buying a remanufactured alternator, can’t you just replace whichever component is broken? Technically, yes. Swapping out the broken parts, such as the pulley, might require special tools, though, FCP Euro notes. Yet if you know which part is likely broken, you could just replace it rather than the whole alternator. And one part is cheaper than the whole assembly.

However, it’s worth noting that most experts recommend not doing wiring repairs yourself. Furthermore, finding individual parts is usually more difficult than finding a whole alternator. It’s not impossible, mind you, especially if your car has a healthy aftermarket community. But what you’ll save in money you’ll often spend on time.

Is it expensive for a mechanic to fix your alternator?

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Speaking of saving money, it’s one of the main reasons why people replace their car alternators themselves. Say you’re not comfortable with the DIY approach, at least for this task, though. How much will going to the mechanic set you back?

As noted earlier, that depends on your car, as well as on local labor rates. But broadly speaking, it’ll cost twice as much as the alternator itself, The Drive claims. So, the $300-$500 repair is now a $600-$1000 job.

There’s nothing wrong with going to a mechanic to replace your alternator, especially if you don’t have time or lack confidence. But if you want to save some cash and build up your skills, it’s something you can tackle at home.

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