The area around the brake booster and master cylinder contains the following components:
1 - brake fluid level control sensor;
2 - connecting the vacuum line from the intake manifold;
3 - brake fluid reservoir;
4 - master brake cylinder;
5 - brake booster.
Removal the master brake cylinder
Pump out the brake fluid from the expansion tank.
To reduce the pressure in the brake booster, remove the vacuum hose.
Remove the reservoir from the master cylinder.
Disconnect all brake hoses from the master cylinder.
Remove both mounting bolts behind the master cylinder.
Carefully remove the master cylinder from the brake booster, avoiding distortion of the cylinder.
When assembling, install a new sealing ring between the brake booster and the brake master cylinder.
Tighten the fastening nut to a torque of 25 Nm.
Before installing the reservoir, the sealing plug of the expansion tank connecting nipple should be moistened from the inside with brake fluid.
Remove air from the brake system.
The article was copied from the website AudiManual