Removal & Installation

NOTE: Vehicles with M30 and M70 engines, master cylinder is mounted on front of brake booster on driver side bulkhead. Vehicles with M60 engines, master cylinder is mounted in left front of engine compartment behind headlight.

Using a syringe, empty brake fluid reservoir. Disconnect brake fluid level sensor wire from reservoir cap. Carefully remove fluid reservoir from master cylinder by pulling straight up.
On 740i/iL models, disconnect fluid supply lines from top of master cylinder. On manual transmission models, remove clutch master cylinder supply hose from side of fluid reservoir.

NOTE: It may be necessary to move aside engine main power connector, diagnostic connector, or hydraulic oil reservoir, for better access to master cylinder fittings.

On all models, disconnect brake fluid lines from master cylinder and plug openings. Remove master cylinder mounting bolts or nuts and discard. Remove master cylinder from brake booster.
Make sure all nuts, fluid couplings, thread bores and mating surfaces are clean.
To install, reverse removal procedure. Use NEW "O" rings on fluid reservoir and master cylinder-to-brake booster. Use NEW master cylinder mounting lock nuts or bolts. Tighten all fasteners to specification. See TORQUE SPECIFICATIONS . DO NOT over torque master cylinder mounting nuts to prevent possible damage to booster.
Connect all brake fluid lines and bleed entire brake system. See BLEEDING BRAKE SYSTEM .