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Home >> Audi >> 2021 >> A4 Quattro Premium Plus, 2.0L Eng VIN B >> Repair and Diagnosis (Single Page) >> Brakes >> Mechanical - Hydraulic >> Hydraulic Components (Brake System) (2 Of 2) >> 47 Hydraulic Components >> Brake Booster/Brake Master Cylinder >> Brake Booster, Removing And Installing >> Installing

Brake Booster, Removing And Installing: Installing

Install in reverse order of removal and note the following:

CAUTION:

Make sure that the actuator pin for the brake lamp is pushed in the brake master cylinder before installing the brake master cylinder. The brake lamp will not function without this pin. Refer to NOTE .

NOTE:

Replace the bolts after removing them.

-- Thoroughly clean the rest of the dripping brake fluid off of the plenum chamber.

-- Check that the boot -2- has not slipped out of the surrounding groove -arrow- on the brake booster -1- as shown.

GWWA47-10254Courtesy of AUDI OF AMERICA, LLC
NOTE:

The boot -2- must sit securely all the way around in the groove -arrow-.

CAUTION:

Make sure that the actuator pin for the brake lamp is pushed in the brake master cylinder before installing the brake master cylinder. The brake lamp will not function without this pin. Refer to NOTE .

-- Carefully insert the brake booster with the brake master cylinder.

-- Install the bolts -arrows- and tighten to the required tightening specification -Item  3-.

GWWA46-10535Courtesy of AUDI OF AMERICA, LLC

-- Push the vacuum hose -2- into the brake booster.

GWWA47-10253Courtesy of AUDI OF AMERICA, LLC

-- Install the Vacuum Sensor -G608- -2-. Refer to Vacuum Sensor -G608-, REMOVING AND INSTALLING 

-- Push the vacuum hose securely onto the Vacuum Sensor -G608-.

NOTE:

Make sure the vacuum hose is connected at all of the separating points.

-- Connect the connector -1- to the Vacuum Sensor -G608- and to the Brake Lamp Switch -F- -4-.

-- Insert the brake lines into the brake master cylinder by hand.

GWWA47-10253Courtesy of AUDI OF AMERICA, LLC

Do not change the shape of the brake lines.

-- Tighten the union bolts -3- for the brake lines to the required tightening specification -Item  1-, -Item  18-

-- Install the brake fluid reservoir. Refer to BRAKE FLUID RESERVOIR, REMOVING AND INSTALLING .

-- Connect the brake pedal to the brake booster.

Vehicles with Manual Transmission

-- Slide the return hose -1- to the clutch master cylinder completely onto the brake fluid reservoir connection.

Fig 1: Identifying Supply Hose & Seals
GWWN30-10128Courtesy of AUDI OF AMERICA, LLC
WARNING:

There is a risk of brake fluid loss. The return hose for the clutch hydraulics -1- must sit correctly and securely on the brake fluid reservoir connection.

Continuation for All Vehicles

-- Install the plenum chamber bulkhead. Refer to OVERVIEW - BULKHEAD .

-- Fill the brake fluid reservoir up to the "MIN" mark.

Fig 2: Brake Fluid Reservoir
GWWA47-10258Courtesy of AUDI OF AMERICA, LLC
NOTE:

Remove all cloths from the vehicle that were previously placed down.

Vehicles with Manual Transmission

Fig 3: Identifying Supply Hose & Seals
GWWN30-10128Courtesy of AUDI OF AMERICA, LLC
WARNING:

There is a risk of brake fluid loss. The return hose for the clutch hydraulics -1- must sit correctly and securely on the brake fluid reservoir connection.

-- Bleed the clutch hydraulics. Refer to the appropriate service information .

Continuation for All Vehicles

-- Bleed the brake system. Refer to HYDRAULIC SYSTEM, BLEEDING .

-- Seal the brake fluid reservoir with the cap: 1.5 ± 0.5 Nm

-- Install the plenum chamber cover. Refer to PLENUM CHAMBER COVER, REMOVING AND INSTALLING .