Remove/install brake booster

AR43.10-S-0350F

Remove/install brake booster

12.03.2020

Model

447 with engine 780.701/702

Modification notes

12.03.2020

Work procedure revised

The whole document

Shown with engine 780.701

1

Brake booster

2

Brake lines

3

Refrigerant line

4

Nuts

5

Bracket

6

Vacuum line

7

Electrical connectors

Shown with engine 780.702

1

Brake booster

8

Vent line

13

Cotter pin

15

Nuts

14

Thrust rod

 Danger

Risk of death when working on component parts and systems with U >= 30 V alternating voltage (AC) or U >= 60 V direct voltage (DC)

Do not touch damaged or defective live component parts and lines or non-insulated electrical connections and lines.

AS00.00-Z-0035-01A

 Caution

Risk of poisoning from swallowing brake fluid. Risk of injury from skin and eye contact with brake fluid

Only pour brake fluid into suitable and appropriately marked containers. Wear protective clothing and eye protection when handling brake fluid.

AS42.50-Z-0001-01A

Topical note

General information on vehicles with high-voltage on-board electrical system and/or lithium-ion battery and/or gaseous-fuel drive system as well as personal protective equipment

AH00.00-Z-0300-01A

Topical note

Brake fluid notes

AH42.50-P-0001-01A

 

Remove/install

1

Reduce vacuum in brake booster (1) by depressing the brake pedal several times.

2

Clean area surrounding cap on brake fluid reservoir and connections of brake lines (2) on master brake cylinder and on hydraulic unit.


Before opening the brake system, it must be ensured that the area around the connecting points has been cleaned completely.
Otherwise minute particles of dirt in the hydraulic components can result in malfunctions and total failure of the brake system.

 Use clean, lint-free rag only.

 Do not use any compressed air for cleaning when the brake system is open.

Assembly cleaner

*BR00.45-Z-1028-04A

3

Remove cap from brake fluid reservoir and take sieve out of brake fluid reservoir.

4

Extract brake fluid from brake fluid reservoir, insert sieve and then reseal brake fluid reservoir.

 Commercially available devices/tools
Extraction bellows

5

Remove refrigerant line (3).

Model 447 with engine 780.701/702
with code HH9 (Air conditioner, automatic heater control)
Model 447 with engine 780.702
with code HH4 (THERMOTRONIC automatic climate control)

AR83.30-S-7835F

6

Remove bracket (5).

Model 447 with engine 780.701/702
with code HH9 (Air conditioner, automatic heater control)
Model 447 with engine 780.702
with code HH4 (THERMOTRONIC automatic climate control)

 To do so, remove nuts (4).

7

Remove brake lines (2).

Note on calculation of tightening torque when using insertion or socket tools with various effective lengths

AH00.00-P-0015-01CW

 Removal: Mark assignment of brake lines (2).

 Collect any escaping brake fluid using suitable rags. Seal connections.
Different retaining screws are installed depending on the given vehicle version.

 Installation: Note assignment of brake lines (2).

 Retaining screw, brake line to hydraulic unit

*BA42.10-N-1003-04D

 Retaining screw, brake line to master brake cylinder

*BA42.10-N-1004-04D

 Box wrench bit

*000589750300

 Box wrench

*000589760300

 Box wrench bit

*140589000300

 Record plug

*129589009100

8

Detach vacuum line (6) from brake booster (1).

 Installation: Check seal for vacuum line (6) in brake booster (1) for damage and leak tightness.

If seal is damaged or no longer seals correctly:



Install new gasket.

9

Remove bleed line (8) from tubular frame.

 Do not remove bleed line (8) from auxiliary circuit expansion reservoir.

 Installation: Check retaining clips for damage.

If damage exists,



Replace damaged retaining clips.

10

Disconnect electrical connectors (7) and place electric lines outside of working area.

11

Remove steering column tube.

AR46.10-S-0400E

12

Remove push rod (14) from brake pedal.

 To do so, remove cotter pin (13).

13

Remove nuts (15).

 Nut, brake booster to firewall

*BA43.10-N-1001-01C

14

Remove brake booster (1) forward.

 Installation: Replace seal between brake booster (1) and firewall.

15

Remove master brake cylinder.

If the brake booster (1) is to be replaced.

AR42.10-S-0300E

16

Modify both vacuum sensors.

If the brake booster (1) is to be replaced.

17

Install in the reverse order.

18

Bleed brake system.

AR42.10-S-0010E



Check

19

Perform brake test.



AP42.00-S-4290E

 Brake lines, brake hoses

Number

Designation

Model 447, 448

BA42.10-N-1003-04D

Retaining screw, brake line to hydraulic unit

Nm

14

 Brake lines, brake hoses

Number

Designation

Model 447, 448

BA42.10-N-1004-04D

Retaining screw, brake line to master brake cylinder

Nm

14

 Brake booster

Number

Designation

Model 447, 448

BA43.10-N-1001-01C

Nut, brake booster to firewall

Nm

20

Repair materials

Number

Designation

Order number

BR00.45-Z-1028-04A

Assembly cleaner

A 000 986 56 01