Bleed brake system

AR42.10-P-0010GS

Bleed brake system

6.12.10

Danger!

Risk of poisoning caused by swallowing brake fluid. Risk of injury caused by brake fluid coming into contact with skin and eyes.

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

AS42.50-Z-0001-01A



Brake fluid notes

All models

AH42.50-P-0001-01A



Notes on repairs to brake system

All models

AH42.00-P-0003-01A

1

Switch off ignition

 The motor/pump unit must not start to run.

2

Eliminate pressure in storage system

 Operate brake pedal 30 times as far as the end stop, in order to eliminate pressure in the storage system.

3

Fill brake fluid into tandem brake master cylinder chamber (11a) and booster chamber (11b) up to the maximum marking

 The brake fluid reservoir must not be completely drained so that no air enters the system. If the brake fluid reservoir is completely emptied, the entire bleeding procedure must be repeated.

The brake system can only be bled with two persons.

4

Connect and switch on bleeder unit on the tandem brake master cylinder chamber (11a)

 Connect in accordance with the unit manufacturer's specifications. Bleed pressure approx. 2 bar.

Brake fluid change unit (for barrel)

gotis://B_42/43.2_01.0

Preliminary bleeding for tandem brake master cylinder chamber (11a)

5

Open bleed screw (3) on each wheel brake cylinder on the rear axle, until the brake fluid exits bubble-free, then close the bleed screw (3)

 Start on the side that is furthest away from the brake booster hydraulic unit (5). Repeat procedure on both wheel brake cylinders until the brake fluid exits bubble-free.

 In each case drain at least 80 cm³ brake fluid from the wheel brake cylinders.

 Always wear safety glasses when working on the brake system. Because of the large volume and the high pressure in the accumulator system there is a risk after opening the bleed screw that the breather hose may slip off whereupon brake fluid may escape at high pressure.



*BA42.10-P-1001-08A

6

Open bleed screws (4) on each front axle brake caliper, until the brake fluid exits bubble-free, then close the bleed screw (4)

 Start on the side that is furthest away from the brake booster hydraulic unit (5). Repeat procedure on both front axle brake calipers until the brake fluid exits bubble-free.

 In each case drain at least 80 cm³ brake fluid from the wheel brake cylinders.



*BA42.10-P-1001-02B

7

Bleed brake booster hydraulic unit (5)

 Open bleed screw on tandem brake master cylinder chamber (1) on the bleeder holder of the brake booster hydraulic unit (5), until the brake fluid exits bubble-free, then close the bleed screw on the tandem brake master cylinder chamber (1). Drain at least 80 cm³ brake fluid.



*BA42.50-P-1001-01C

Bleeding booster circuit

8

Connect and switch on bleeder unit on booster chamber (11b)

 Connect in accordance with the unit manufacturer's specifications. Bleed pressure approx. 2 bar.

Brake fluid change unit (for barrel)

gotis://B_42/43.2_01.0

9

Fill brake fluid reservoir up to minimum marking

10

Switch off bleeder unit, wait for 30 seconds then switch on again

11

Fill brake fluid reservoir up to maximum marking

 The brake fluid reservoir must not be completely drained so that no air enters the system. If the brake fluid reservoir is completely emptied, the entire bleeding procedure must be repeated.

The brake system can only be bled with two persons.

12

Switch off and disconnect bleeder unit

13

Switch on ignition

 The motor/pump unit starts to run and it has to run until it audibly switches off, ignition remains switched on.

14

Press brake pedal all the way down 10-times

 If the motor/pump unit audibly switches off, switch off ignition.

15

Carefully open booster chamber bleed screw (2) on bleeder holder of brake booster hydraulic unit (5) with brake pedal actuated

 Wear safety glasses.

The large volume and the high pressure in the accumulator system mean that when the bleed screw is opened the breather hose may slip off.

16

Permanently check the fill level of the brake fluid reservoir

 During the following operation steps, care must be taken to ensure that brake fluid is present so that no air is sucked in.

17

When the brake fluid exits bubble-free and the accumulators are drained, close the bleed screw on the booster chamber (2)

 Drain approximately 250 cm³ brake fluid.



*BA42.50-P-1001-01C

18

Fill booster chamber (11b) up to maximum marking

Front axle bleeding

19

Switch on ignition

 The motor/pump unit starts to run and it has to run until it audibly switches off, ignition remains switched on.

20

Open bleed screw (4) on each of the front axle brake calipers, press brake pedal all the way down, close bleed screw (4) and release brake pedal

 Start on the side that is furthest away from the brake booster hydraulic unit (5). Repeat procedure on both front axle brake calipers until the brake fluid exits bubble-free. Drain at least 80 cm³ brake fluid.



*BA42.10-P-1001-02B

21

Switch off ignition

 The motor/pump unit must not start to run.

22

Eliminate pressure in storage system

 Operate brake pedal 30 times, in order to eliminate pressure in the storage system.

23

Open bleed screw (4) on each of the front axle brake calipers, press brake pedal all the way down, close bleed screw (4) and release brake pedal

 Start on the side that is furthest away from the brake booster hydraulic unit (5). Repeat procedure on both brake calipers until the brake fluid exits bubble-free. Drain at least 80 cm³ brake fluid.



*BA42.10-P-1001-02B

24

Switch on ignition

 The motor/pump unit starts to run and it has to run until it audibly switches off, ignition remains switched on.

25

Open bleed screw (4) on each of the front axle brake calipers, press brake pedal all the way down, close bleed screw (4) and release brake pedal

 Start on the side that is furthest away from the brake booster hydraulic unit (5). Repeat procedure on both brake calipers until the brake fluid exits bubble-free. Drain at least 80 cm³ brake fluid.



*BA42.10-P-1001-02B

Rear axle bleeding

26

Open bleed screw on tandem brake master cylinder chamber (1) on bleeder holder of brake booster hydraulic unit (5), press brake pedal all the way to the end stop, close bleed screw on tandem brake master cylinder chamber (1) and release brake pedal

 Ignition remains switched on, boost must be present.

Repeat this procedure until brake fluid exits free of bubbles. Drain at least 80 cm³ brake fluid.

 During the following operation steps, care must be taken to ensure that brake fluid is present so that no air is sucked in.



*BA42.50-P-1001-01C

27

Open bleed screw on each of the rear wheel brake cylinders, press brake pedal all the way down, close bleed screw and release brake pedal

 Start on the side that is furthest away from the brake booster hydraulic unit (5). Repeat procedure on both wheel brake cylinders until the brake fluid exits bubble-free. Drain at least 80 cm³ brake fluid.

 During the following operation steps, care must be taken to ensure that brake fluid is present so that no air is sucked in.



*BA42.10-P-1001-08A

Concluding work

28

Eliminate pressure in storage system

 Switch off ignition, press brake pedal 30-times all the way to the end stop.

29

Fill brake fluid level in booster chamber (11b) to maximum marking, and correct in the tandem brake master cylinder chamber (11a)

 The maximum marking of the booster chamber (11b) is designed such that the brake fluid level also has to reach this level even when the accumulator system has been depressurized.

30

Mount threaded cap and fasten finger-tight

31

Check brake pressure additional hydraulics warning lamp (E16/5)

 The full brake system boost is given when the brake pressure additional hydraulics warning lamp (E16/5) goes off after the ignition is switched off.

Number

Designation

Model 461, 463

BA42.10-P-1001-02B

Bleed screw at front axle fixed brake caliper

Nm

14

Number

Designation

Model 463.236/
248 with code 979

BA42.50-P-1001-01C

Bleed screw on brake booster hydraulic unit

Nm

12

Number

Designation

Model 463

BA42.10-P-1001-08A

Bleed screw to rear axle wheel brake cylinder

Nm

14