34 31 181 Removing and installing / replacing expansion tank for hydraulic brake actuation

WARNING: This page is about a different car, the 2005 BMW 645Ci and 2004 BMW 645Ci. However, it is still accessible from the selected car via links, so may be relevant.

Necessary preliminary tasks:

Remove lower section of microfilter housing, refer to 64 31 061 REMOVING AND INSTALLING/REPLACING LEFT OR RIGHT MICROFILTER HOUSING LOWER SECTION .
Read and comply with General Information, refer to 34 00 ... GENERAL INFORMATION .

Suck the brake fluid out of the expansion tank. Use suction bottle exclusively to draw off brake fluid.

IMPORTANT: Do not reuse drawn out brake fluid.

Fig 1: Draining Brake Fluid From Expansion Tank

Courtesy of BMW OF NORTH AMERICA, INC.

Unfasten plug connection (1) and disconnect. Release retaining screw (2).

Fig 2: Disconnecting Plug Connection

Courtesy of BMW OF NORTH AMERICA, INC.

Installation:

Tightening torque, refer to 34 31 3AZ in BRAKES - TIGHTENING TORQUES - 645CI .

Pull expansion tank vertically out of brake master cylinder.

Installation:

Check rubber plug in brake master cylinder for damage and replace if necessary. Push the expansion tank vertically onto the master brake cylinder.

Fig 3: Installing Expansion Tank Onto Master Brake Cylinder

Courtesy of BMW OF NORTH AMERICA, INC.