The BMW E46 is the generation of BMW 3 Series offered from late 1999 through 2006. The coupe and sedan models shared many engineering characteristics, including the alternator assembly. Replacement of the alternator is a straightforward procedure that will take about an hour and a few simple tools.
Remove the air box, using a 12mm socket wrench and pliers, by unscrewing the four securing nuts at its sides, which mount it to the engine bay and secure it in place.
Open the BMW's trunk and remove the plastic casing that sits on top of the battery to reveal the battery housing.
Disconnect both the positive and negative terminals from the battery.
Disconnect the power wire that is attached to the alternator using the 12mm socket wrench.
Loosen and remove the bolt that sits at the center of the alternator using a 17mm socket wrench.
Find the alternator belt's pulley cover and pry it off. Remove the bolt beneath it using a 16mm socket wrench.
Pull the alternator out, hitting it with a rubber mallet as necessary. If it seems to be stuck, forcefully hit it on alternate sides with the rubber mallet until it wiggles out enough for you to pull it out.
Slide the new alternator into place until it fits snugly.
Loosen the alternator belt pulley with a 16mm socket wrench and thread the alternator belt so it is back on the alternator pulley.
Replace the alternator pulley's plastic cap to protect it from corrosion.
Reinstall the long bolt that goes into the center of the alternator by using a 17mm socket wrench.
Reconnect the power wire to the alternator using a 12mm socket wrench.
Reconnect the positive and negative terminals to the battery and reinstall the battery housing's plastic cover.
Close the BMW's hood to complete the installation and start your car to ensure that the alternator is functioning correctly.
