Necessary preliminary tasks

WARNING: This page is about a different car, the 2010 BMW 650i, 2009 BMW 650i, 2008 BMW 650i, 2007 BMW 650i, and 2006 BMW 650i. However, it is still accessible from the selected car via links, so may be relevant.

Disconnect battery. See 61 20 900 DISCONNECTING AND CONNECTING BATTERY NEGATIVE LEAD
Remove underbody protection
Remove exhaust system. See 18 00 020 REMOVING AND INSTALLING COMPLETE EXHAUST SYSTEM (CONV.) or 18 00 020 REMOVING AND INSTALLING COMPLETE EXHAUST SYSTEM (COUPE) .
Remove heat shields
Support transmission and release transmission crossmember. See 22 31 001 REPLACING RUBBER MOUNT FOR TRANSMISSION MOUNTING
Lower transmission

Release screws (1).

Tightening torque 23 41 7AZ .

Remove expansion tank (2) in direction of arrow.

Fig 1: Removing Expansion Tank

Courtesy of BMW OF NORTH AMERICA, INC.

Installation:

Replace sealing ring.

Moisten sealing ring (1) with Pentosin and push onto tank fitting.

Fig 2: Identifying Sealing Ring

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: After completing work:

Check fluid level in hydraulic system. See 21 53... CHECKING/TOPPING UP FLUID LEVEL IN HYDRAULIC SYSTEM (GS6S37BZ/GS6S53BZ/ SMG)
Perform "Teach in transmission" service function by means of DIS Tester (BMW scan tool)