How to Replace the Mercedes 300E Alternator

1. Open the hood. Use a wrench to disconnect the negative battery cable from the battery. It is always advisable to disconnect the battery when working on a car's electrical system.
2. Loosen the adjustment bolt until the alternator belt has enough slack to be pulled off the alternator pulley. Disconnect the electrical leads and voltage regulator harness from the alternator.
3. Use a ratchet and socket to remove the alternator's mounting bolts. Pull the alternator from the mounting bracket.
4. Put the new alternator onto the mounting bracket. Insert the mounting bolts and tighten them with the ratchet and socket.
5. Pull the alternator belt back onto the pulley and tighten the adjusting bolt until the belt is taut.
6. Plug the voltage regulator and electrical leads into the new alternator and reconnect the negative cable to the battery.