Necessary preliminary work:
Release connector (1) and remove.
Slacken nut (2).
Disconnect positive battery cable from alternator.
Slacken nut (1).
Remove cover from idler pulley and undo bolt (1) beneath it.
Remove idler pulley.
Release screws (1).
Feed out alternator upwards and remove.
NOTE: Check stored fault messages.
Delete fault memory.
BMW X3 Service & Repair Manual > Output shafts: Removing and installing/replacing both output shafts
IMPORTANT:
The RADIAL SHAFT SEAL FOR THE OUTPUT SHAFT should be renewed every
time the output shaft is removed and installed.
The circlip of the output shaft must be replaced after re-installation.
NOTE: The procedure is described in PRESSING OUTPUT SHAFT OUT OF DRIVE
FLANGE AN ...