There are certain parts of your car that, if removed or broken, disable your car immediately. Obviously without wheels, your car won't roll and without a transmission, it won't move either. Then, there are other parts, that if removed, won't make a bit of difference in getting you to your destination. Your car will handle the same without its tail lights, rear seat, or radio. (The police may have something to say about the tail lights, however.) Finally, there are those parts that if removed, don't seem to make any immediate difference, but slowly disable your car over time. Your alternator is one of those parts.

The alternator's job is to recharge the battery and provide electricity to the car when it's running. Let's say you have a defective alternator. Your car will still start off the battery, and you'll be able to drive it...for a while. However, as you drive down the road, you'll slowly deplete the battery since it's not being recharged by the alternator and your car will eventually stop when you battery is too low to fire the spark plugs. Your battery will run down much faster if you're using you air conditioner, heater or headlights. When your alternator begins to fail, you get little notice other than an ignition system warning light in your instrument cluster and if you don't notice or ignore the warning light, and keep driving, eventually you'll drain the battery and your car will stop running.

If you're unsure of your alternator's condition, you can give it a quick test with a volt meter. With the engine running, you place one of the volt meter's terminals on the alternator's positive power post and touch the other terminal to a vehicle ground. A properly functioning alternator should give a reading of around 14 volts.

Thankfully, an alternator is an easy DIY replacement item. Although placement will vary by make and model of car, they tend to have a lot in common. Most alternators are mounted to a bracket with a single bolt on which the alternator can pivot, and another bolt that adjusts the tension for the alternator belt. The alternator pulley is powered by a belt driven off the crankshaft. Sometimes this belt will also power another accessory, such as the A/C compressor or the power steering pump. You may have multiple belts powering multiple accessories, or your engine might have a single serpentine belt powering all the accessories. Your car's alternator might be mounted right near the top of the engine compartment, or it might be low enough that you need to put the car up on ramps or jack stands in order to change it.

There are aftermarket alternators out there, but for the most part, your options are limited to identical new units or quality rebuilt alternators. No matter which one you choose, replacing the alternator is usually as simple as releasing tension and removing the belt, and then removing the bolts that hold the alternator to the bracket. From there, you just install the new alternator and belt and then tighten the bolts to the factory-specified torque value. Thankfully there are plenty of videos on YouTube that can show you step by step exactly how to do it.

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