Checking brake booster

AR43.10-P-0325MFA

Checking brake booster

06.03.2020

Model

118, 177, 247

4

Brake booster

4

Brake booster

5

Test connection

6

Check valve

7

Tester

8

Pedal force meter

9

Vacuum tester

 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

Notes on externally invisible brake fluid loss

AH42.10-P-9406-02A

Topical note

Notes on repairs to brake system

AH42.00-P-0003-01A

Topical note

Brake fluid notes

AH42.50-P-0001-01A



Remove

1

Remove left front wheel and tire assembly.

AR40.10-P-1102MFA

2

Remove heat shield for firewall.

Model 118, 177, 247 with engine 260
Model 118, 177, 247 with engine 282
Model 118, 177, 247 with engine 654
Model 247 with engine 608

Model 247 with engine 608

AR49.10-P-0001MFE

Model 118, 177, 247 with engine 282

AR49.10-P-0001MFD

Model 118, 177, 247 with engine 260

AR49.10-P-0001MFC

Model 118, 177, 247 with engine 654

AR49.10-P-0001MFF

3

Remove cover above brake fluid expansion reservoir.

4

Clean area around cap on brake fluid expansion reservoir.


Before opening, clean the area surrounding the cap thoroughly.
Otherwise dirt particles in the hydraulic component parts can result in malfunctions and total failure of the brake system.

Assembly cleaner

*BR00.45-Z-1028-04A

5

Unscrew cap on brake fluid expansion reservoir and suction off some brake fluid.

 Hand pump

*210589007100



Check

 Warning

Risk of accident from vehicle starting off by itself when engine running. Risk of injury (bruises and burns) resulting from working on the engine while it is being started or when it is running.

Secure vehicle to prevent it from starting off by itself. Wear closed and snug-fitting work clothes. Do not touch hot or rotating parts.

AS00.00-Z-0005-01A

6

Connect filling unit to brake fluid reservoir.



000 588 01 82 00 Filling unit

WS25.00-P-0016B



General brake fluid

BB00.40-P-0330-01A



Brake fluids (DOT 4 plus)

BB00.40-P-0331-00A

7

Reduce vacuum in brake booster (4) by depressing brake pedal several times.

8

Connect vacuum tester (9) with test connection (5) to brake booster (4).

AR43.10-P-0024-01V

 Vacuum tester

*201589132100

 Test connection

*168589086300

9

Remove vent screw from front brake caliper on the driver's side and connect test equipment (7).



000 588 07 21 00 Test equipment

WS42.00-P-0014B


Use correct connection fitting (pitch, centering cone, etc.).
Leaks and measurement errors can otherwise occur.

10

Bleed test equipment (7).



000 588 07 21 00 Test equipment

WS42.00-P-0014B

11

Connect pedal force meter (8) at brake pedal.

 Commercially available devices/tools
Pedal force meter (8)

12

Start the engine and generate specified vacuum.

 If this vacuum is not reached or it drops immediately, the seal between the brake booster (4) and master brake cylinder may be damaged or the check valve (6) may be defective.

Model 118.### 1# with engine 260
Model 118.### 1# with engine 282
except code 950 (AMG sport package)
except code U29 (Brake system with larger brake disks on the front axle)
Model 118.### 1# with engine 282
with code 950 (AMG sport package)
Model 118.### 1# with engine 282
with code U29 (Brake system with larger brake disks on the front axle)
Model 118.### 1# with engine 608
except code 950 (AMG sport package)
except code U29 (Brake system with larger brake disks on the front axle)
Model 118.### 1# with engine 608
with code 950 (AMG sport package)
Model 118.### 1# with engine 608
with code U29 (Brake system with larger brake disks on the front axle)
Model 118.### 2# Brake line pressure

*BE43.10-P-1004-01J

Model 177.### 1# with engine 260
Model 177.### 1# with engine 282
except code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN))
Model 177.### 1# with engine 608
Model 177.### 2# with engine 260, 608
Model 177.### 2# with engine 282
except code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN))Brake line pressure

*BE43.10-P-1004-01H

Model 247.### 1# with engine 282
Model 247.### 1# with engine 608
Model 247.### 2#
Model 247.0## 1# with engine 654
except code U29 (18-inch brake system)
Model 247.0## 1# with engine 654
with code U29 (18-inch brake system)Brake line pressure

*BE43.10-P-1004-01I

If the vacuum is not reached.



Switch off engine, and check seal between brake booster (4) and master brake cylinder as well as the check valve (6).

AR42.10-P-0300MFA

AR43.10-P-0023MFA

13

Replace seal between brake booster (4) and master brake cylinder.

If the specified vacuum has not been reached or if it drops off straight away and the check valve (6) is not defective.

AR42.10-P-0300MFA

14

Apply specified force to brake pedal and read off line pressure on test equipment (7).



000 588 07 21 00 Test equipment

WS42.00-P-0014B

Model 118.### 1# with engine 260
Model 118.### 1# with engine 282
except code 950 (AMG sport package)
except code U29 (Brake system with larger brake disks on the front axle)
Model 118.### 1# with engine 282
with code 950 (AMG sport package)
Model 118.### 1# with engine 282
with code U29 (Brake system with larger brake disks on the front axle)
Model 118.### 1# with engine 608
except code 950 (AMG sport package)
except code U29 (Brake system with larger brake disks on the front axle)
Model 118.### 1# with engine 608
with code 950 (AMG sport package)
Model 118.### 1# with engine 608
with code U29 (Brake system with larger brake disks on the front axle)
Model 118.### 2# Brake line pressure

*BE43.10-P-1004-01J

Model 177.### 1# with engine 260
Model 177.### 1# with engine 282
except code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN))
Model 177.### 1# with engine 608
Model 177.### 2# with engine 260, 608
Model 177.### 2# with engine 282
except code ME08 (Hybrid drive 75-84 kW VARIANT (INCLUDING PLUGIN))Brake line pressure

*BE43.10-P-1004-01H

Model 247.### 1# with engine 282
Model 247.### 1# with engine 608
Model 247.### 2#
Model 247.0## 1# with engine 654
except code U29 (18-inch brake system)
Model 247.0## 1# with engine 654
with code U29 (18-inch brake system)Brake line pressure

*BE43.10-P-1004-01I

 Adapter for brake pedal winch

*211589003100

 Brake pedal jack

*000589183100

If the line pressure is not reached.



Replace brake booster (4).

AR43.10-P-0350MFA

15

Switch off engine.

16

Remove pedal force meter (8) from brake pedal.

 Commercially available devices/tools
Pedal force meter (8)

17

Disconnect vacuum tester (9) with test connection (5) from brake booster (4).

AR43.10-P-0024-01V

 Vacuum tester

*201589132100

 Test connection

*168589086300

18

Disconnect test equipment (7) with connection fitting and screw in vent screw all the way at brake caliper on the driver's side.



000 588 07 21 00 Test equipment

WS42.00-P-0014B

19

Bleed brake caliper on the driver's side.



000 588 01 82 00 Filling unit

WS25.00-P-0016B

AR42.10-P-0010-02MFA

 Bleed screw at brake caliper

*BA42.10-P-1004-10ZA

20

Disconnect filling unit from brake fluid reservoir.



000 588 01 82 00 Filling unit

WS25.00-P-0016B



General brake fluid

BB00.40-P-0330-01A



Brake fluids (DOT 4 plus)

BB00.40-P-0331-00A

21

Check and correct fluid level in brake fluid reservoir.



AP42.10-P-4210D



Install

22

Screw on cap of brake fluid expansion reservoir.

23

Install cover above brake fluid expansion reservoir.

24

Install heat shield for firewall.

Model 118, 177, 247 with engine 260
Model 118, 177, 247 with engine 282
Model 118, 177, 247 with engine 654
Model 247 with engine 608

Model 247 with engine 608

AR49.10-P-0001MFE

Model 118, 177, 247 with engine 282

AR49.10-P-0001MFD

Model 118, 177, 247 with engine 260

AR49.10-P-0001MFC

Model 118, 177, 247 with engine 654

AR49.10-P-0001MFF

25

Install left front wheel and tire assembly.

AR40.10-P-1102MFA

Check values for pneumatic brake booster

Number

Designation

Model 177.### 1# with engine 654 with code 411 with code B01,
model 177.### 1# with engine 654 with code M013 except code 950/U29,
model 177.### 2# with engine 260/608,
model 177.### 2# with engine 282 except code ME08

Model 177 with engine 282 with code ME08,
model 177.### 1# with engine 139/260,
model 177.### 1# with engine 654 with code 950/U29,
model 177.### 1# with engine 654 with codeB01 except code 411

BE43.10-P-1004-01H

Brake line pressure

Vacuum 0.92…0.98 bar

Force on brake pedal (force to input rod for pedal -i = 3.3)

165 N

bar

18

21

330 N

bar

43

44

495 N

bar

67

68

660 N

bar

92

91

825 N

bar

111

113

Check values for pneumatic brake booster

Number

Designation

Model 177.### 1# with engine 282 except code ME08,
model 177.### 1# with engine 608
model 177.### 2# with engine 139/654

BE43.10-P-1004-01H

Brake line pressure

Vacuum 0.92…0.98 bar

Force on brake pedal (force to input rod for pedal -i = 3.3)

165 N

bar

21

330 N

bar

44

495 N

bar

68

660 N

bar

91

825 N

bar

113

Check values for pneumatic brake booster

Number

Designation

Model 247.### 1# with engine 282 except code ME08,
model 247.### 1# with engine 608,
model 247.0## 1# with engine 654 except code U29 (18 inch brake system)

Model 247.### 1# with engine 260T model 247.### 1# with engine 282 with code ME08,
model 247.0## 1# with engine 654 with code U29 (18 inch brake system),
model 247.6## 1# with engine 654

BE43.10-P-1004-01I

Brake line pressure

Vacuum 0.92…0.98 bar

Force on brake pedal (force on input rod where pedal i = 3.3)

165 N

bar

18

21

300 N

bar

43

44

495 N

bar

67

68

660 N

bar

92

91

825 N

bar

111

113

Check values for pneumatic brake booster

Number

Designation

Model 247.### 2#

BE43.10-P-1004-01I

Brake line pressure

Vacuum 0.92…0.98 bar

Force on brake pedal (force on input rod where pedal i = 3.3)

165 N

bar

21

300 N

bar

44

495 N

bar

68

660 N

bar

91

825 N

bar

113

Check values for pneumatic brake booster

Number

Designation

Model 118.### 1# with engine 139/260
model 118.### 1# with engine 282/608/654 with code 950/U29

Model 118.### 1# with engine 282/608/654 except code 950/U29

BE43.10-P-1004-01J

Brake line pressure

Vacuum 0.92…0.98 bar

Force on brake pedal (force on input rod where pedal i = 3.3)

165 N

bar

21

18

300 N

bar

44

43

495 N

bar

68

67

660 N

bar

91

92

825 N

bar

113

111

Check values for pneumatic brake booster

Number

Designation

Model 118.### 2#

BE43.10-P-1004-01J

Brake line pressure

Vacuum 0.92…0.98 bar

Force on brake pedal (force on input rod where pedal i = 3.3)

165 N

bar

21

300 N

bar

44

495 N

bar

68

660 N

bar

91

825 N

bar

113

 Front axle brake caliper

Number

Designation

Model 118

Model 177

BA42.10-P-1004-10ZA

Bleed screw at brake caliper

M10

Nm

18

18

 Front axle brake caliper

Number

Designation

Model 247

BA42.10-P-1004-10ZA

Bleed screw at brake caliper

M10

Nm

18

Repair materials

Number

Designation

Order number

BR00.45-Z-1028-04A

Assembly cleaner

A 000 986 56 01