1999 AUDI A4 light

47-31


7 -
Brake servo
On gasoline engines vacuum is supplied
from the intake manifold On Diesel engines vacuum is supplied from
the vacuum pump
Functional check:
- With engine switched off, depress brake
pedal firmly several times (to deplete
vacuum in brake servo).
- Depress and hold brake pedal with
average foot pressure and start engine. If
servo is working properly, pedal will be
felt to give slightly under foot (servo
assistance becomes effective).
If malfunctioning:
- Replace as complete unit only.Check valve in vacuum hose - 9 -Removing and installing page 47
-37
Adjusting ball head Fig. 1
Pa
ge 3 of 15 Brake master c
ylinder with 23.81 mm
(0.937 in.
) piston diameter and brake servo, com
ponent summar
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p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.SU03.47.6

47-36

Installing
When installing, note the following points:

- When installing brake master cylinder onto
brake servo, make sure push rod is correctly
located in brake master cylinder.

- Apply slight pressure to brake pedal to move
push rod toward brake master cylinder; this
makes it easier to guide brake master cylinder
onto push rod.

Bleeding clutch hydraulics

- Connect US1116 brake bleeder but do not
switch on yet.

- Open bleeder screw on clutch slave cylinder.

- Attach collector bottle hose.

- Switch on bleeder unit and allow approx. 100 cc
(6 oz.) of brake fluid to flow out of clutch slave
cylinder.

- Close bleeder screw.

Pa
ge 9 of 15 Brake master c
ylinder with 23.81 mm
(0.937 in.
) piston diameter and brake servo, com
ponent summar
y
11/20/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.SU03.47.6

47-39


Releasing brake pedal
- Remove brake light switch.
1 -
Inserting T10006 brake pedal release tool
Insert the tool from below
2 -
Release procedures
- Tightly hold brake pedal.
- Lift catches off ball head using a slight
pull on tool (arrow -A-).
- Tension tool so catches do not re-
engage ball head.
- Pull brake pedal from ball head (arrow -
B-).
- Remove brake servo from plenum
chamber together with brake master
cylinder.
Pa
ge 14 of 15 Brake master c
ylinder with 23.81 mm
(0.937 in.
) piston diameter and brake servo, com
ponent summar
y
11/20/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.SU03.47.6

47-40

Installing
Note the following points:

- Adjust brake light switch page 46
-50
.

- Adjust vent valve for cruise control system
page 46
-54
.
Bleeding clutch hydraulics

- Connect US1116 brake bleeder but do not
switch on yet.

- Open bleeder screw on clutch slave cylinder.

- Attach collector bottle hose.

- Switch on bleeder unit and allow approx. 100 cc
(6 oz.) of brake fluid to flow out of clutch slave
cylinder.

- Close bleeder screw.

- Bleed brake system page 47
-23
.
Pa
ge 15 of 15 Brake master c
ylinder with 23.81 mm
(0.937 in.
) piston diameter and brake servo, com
ponent summar
y
11/20/2002 htt
p://127.0.0.1:8080/audi/servlet/Dis
play?action=Goto&t
yp
e=re
pair&id=AUDI.B5.SU03.47.6