How to Replace a Worn Alternator Pulley

If you are having problems with your vehicle not charging the battery, the problem could be a defective alternator pulley. Replacing a broken, cracked or worn out alternator pulley is not very difficult, and it's something you can do yourself in half an hour or so. In fact, you can use this simple how-to guide to learn everything you need to know about replacing an alternator pulley.

Step 1 - Remove Negative Battery Cable

Because the alternator in your vehicle is part of your car's electrical system, you should remove the negative battery cable from the terminal post on a car battery. This will help you avoid shock or injury while working on your car.

Step 2 - Loosen and Remove the Alternator Belt

First, locate the alternator in your vehicle. In most cases, it will be located near the front of the engine area and close to the radiator fan. You will also notice a rubber belt attached to the pulley and alternator. Take an appropriate size wrench or socket and loosen the tension on the belt. Then remove the alternator belt from the pulley and alternator.

Step 3 - Remove Pulley Bolts

Locate the bolts or nut that hold the pulley in place and attach it to the alternator. Sometimes, the bolts on alternator pulleys can be very stubborn and hard to remove, so you may want to use a penetrating spray such as WD-40 to lubricate the bolts so that they are easier to turn. After applying the penetrating spray, use the correct size wrench or socket to remove the bolts.

Step 4 - Remove Old Pulley

After you've successfully removed the bolts, take the pry bar and hammer and gently tap the rear of the pulley. This will help to loosen the pulley so that you can remove it from the alternator. After removing the old pulley, simply set it aside or discard it.

Step 5 - Install New Alternator Pulley

Take the new alternator pulley and line up the bolt holes so that they are in line with the holes on the alternator. Then, take the bolts and insert them into the holes. Tighten them with a socket wrench or torque wrench. You may want to refer to the car owner's manual for your vehicle to determine how much torque to apply to the alternator pulley bolts.

Step 6 - Tighten Alternator Belt

Take the alternator belt and place it back on the alternator and pulley. Then, pull the belt tensioner tight and use a socket wrench to tighten the alternator belt.

Step 7 - Replace the Negative Battery Cable

Reconnect the negative battery cable to the terminal post on your car's battery.

Step 8 - Test the installation

Crank engine and observe battery voltage. I should be above 13 volts.