How to Replace the Alternator on a 2001 BMW

1. Disconnect the battery cable that goes to the negative terminal on the battery. Loosen the hose clamp that holds the mass air flow sensor tubing to the air box.
2. Unplug the harness for the mass air flow sensor. Remove the bolts that hold the air box onto the engine. The number and size of bolts will vary, depending on the model. Set the air box aside.
3. Remove the cold air snorkel in the center-front of the engine by carefully prying the plastic rivets up and then pulling the snorkel off.
4. Loosen the belt tensioner with a socket and ratchet until the belt is loose. Slide the belt off the pulley for the alternator. Disconnect the wires that go to the back of the alternator, noting where they go, for later reassembly.
5. For added clearance, remove the two bolts that hold the power steering reservoir on and set the reservoir out of the way. Remove the upper and lower alternator mounting bolts that bolt the alternator in place. Remove the alternator. You may need to use a pry bar or the tap the alternator to loosen it from the bracket.
6. Install the pulley from the old alternator on the new alternator, if it does not have one. Reinstall the alternator and tighten the two bolts. Plug the alternator back in. Install the belt and tighten the belt tensioner.
7. Reinstall the power steering pump reservoir. Reinstall the cold air snorkel and the air box. Reconnect the wire for the MAF and the battery cable.