1998 JAGUAR X308 brake vacuum hose

Brake System - General Inform
ation - Brake System
D
iagnosis and Testing
Principles of Operations
The brake system operates by transferring effort applied to th e brake pedal, by the driver to the brakes at each wheel.
The braking effort is distributed to each wheel, using a hydraulic system. The system is assisted using a vacuum brake
booster that reduces pedal effort for a given hydraulic pressure. The parking brake operates on the rear wheels and is
applied using a hand operated control.
I
nspection and Verification
•
NOTE: Prior to carrying out any diagno
sis, make sure that the brake system warning indicator is functional.
Visually examine the front and rear tire and wheel assemblies for damage such as un even wear patterns, tread worn out or
sidewall damage. Verify the tires are th e same size, type and, where possible, same manufacture. Replace the damaged
wheel or excessively worn tire. For a dditional information, refer toSection 204
-0
4 Wheels and Tires
.
W
heels and tires must be cleared of an
y foreign matter and tire pressures ad justed to the correct specification.
If the tires exhibit uneven wear or feathering, the cause must be corrected. Check the steering and suspension components
for damage or wear and, if ne cessary, check and adjust front wheel alignment. For additional information, refer toSection
204
-00 Suspen
sion System
- General Informati
on
.
Road Test


V
isual Inspection Chart
Carr

y out a road test to compare actual vehicle braking performance with the
performance standards expected by the
driver. The ability of the test driver to make valid compar isons and detect performance deficiencies will depend on
experience.
The driver should have a thorough knowledge of brake system operation and accepted general performance guidelines to
make good comparisons and de tect performance concerns.
An experienced brake technician will always establish a route that will be used for all br ake diagnosis road tests. The roads
selected will be reasonably smooth and level. Gravel or bump y roads are not suitable because the surface does not allow the
tires to grip the road equally. Crowned roads should be avoide d because of the large amount of weight shifted to the low set
of wheels on this type of road. Once th e route is established and consistently used, the road surface variable can be
eliminated from the test results.
Before a road test, obtain a complete description of the customer concerns or suspec ted condition. From the description, the
technician's experience will allow the te chnician to match possible causes with symptoms. Certain components will be
tagged as possible suspects while others wi ll be eliminated by the evidence. More importantly, the customer description can
reveal unsafe conditions which should be ch ecked or corrected before the road test. The description will also help form the
basic approach to the road test by narrowing the concern to specific components, vehicle speed or conditions.
Begin the road test with a general brake performance check. Keeping the description of the concern in mind, test the brakes
at different vehicle speeds using both ligh t and heavy pedal pressure. To determine if the concern is in the front or rear
braking system, use the brake pe dal and then use the parking brake control. If the condition (pull, vibration, pulsation)
MechanicalElectrical
Brake m
aster cylinder
Parkin
g brake switch
Brake ca

liper piston(s)
D
amaged or corroded wiring harness
Brake di

scs
B
rake master cylinder fluid level switch
Wh

eel bearin
gs
Brake pads
Power brake booster
Brake ped

al linkage
Boost

er vacuum hose
Tire

s
De

bris

Are th
ere any external brake system leaks?
Yes REPAIR as necessary. ADD fluid and BLEED the brak e system. For additional information, refer to
General Procedures in this section. TEST the system for normal operation.
No GO to F3
.
F
3: CARRY OUT A BRAKE MASTER CYLINDER BYPASS TEST
Te

st for brake master cylinder bypass condition. Re
fer to Brake Master Cylinder Component Test in
this section.
1
A
re any concerns found?
Yes INSTALL a new brake master cylinder, ADD flui d and BLEED the brake system. For additional
information, refer to General Proc edures in this section. TEST the system for normal operation.
No System is OK.
PINPO
INT TEST G : EXCESSIVE BRAKE PEDAL EFFORT
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
G1

: CHECK BRAKE PADS
Check the brake pads for wear, contamin

atio
n, correct installation, damage and type.
1
A
re any concerns found?
Yes INSTALL the front brake pads correctly or INSTALL ne w front brake pads if necessary. For additional
information, refer toSection 206
-03
Front Disc Brake
. INSTALL the
rear brake pads correctly or
INSTALL new rear brake pads if necessary. For additional information, refer toSection 206
-04
Rear
Di

sc Brake
. REPEAT road test.
No

GO to G2
.
G2:
CHECK VACUUM
Di

sconnect the vacuum booster hose from the booster.
1
Conne

ct a vacuum/pressure tester to the vacuum hose.
2
Ru

n the engine at normal operating temperature.
3
Re

cord the vacuum reading.
4
Is

the reading 40.5kPa (1
2 in-Hg) or greater?
Yes GO to G3
.
No

LOCATE and REPAIR the source of low vacuum . TEST the system for normal operation.
G3
: INSPECT SYSTEM
Swi

tch the engine off.
1
Re

connect the vacuum hose.
2
Inspect th

e brake booster, rubber grommet, and al
l vacuum plumbing for cracks, holes, damaged
connections, or missing clamps.
3
Pump th
e brake pedal several time
s to exhaust the vacuum. Push down on the brake pedal and hold.
4
Does th
e brake pedal move down
when the engine is started?
Yes Vacuum system is OK.
No GO to G4
.
G4
: CHECK POWER BRAKE BOOSTER VALVE
Check the brake booster valve. For
add
itional information, refer to
Brake Booster in this section.
1
Is th
e power brake booster valve OK?
Yes CHECK the brake booster. Fo r additional information, refer to Brak e Booster in this section. INSTALL a
new brake booster if necessary. TEST the system for normal operation.
No INSTALL a new brake booster valve. TEST the system for normal operation.
P
INPOINT TEST H : BRAKE LOCKUP
DURING LIGHT BRAKE PEDAL FORCE
TE
ST
CONDITIONS
D
ETAILS/RESULTS/ACTIONS
H1

: TEST BRAKE LOCKUP

Comp
onent Tests
Bra
k
e Booster
1.
1. Chec k all
hoses and connections. All unused vacuum connectors should be capped. Hoses and their connections
should be correctly secured and in good condition with no holes and no collapsed areas. Inspect the valve on the
brake booster for damage.
2. 2. Check the hydraulic brake system for leaks or low fluid.
3. 3. With the transmission in PARK, stop the engine and apply the parking brake. Pump the brake pedal several times
to exhaust all vacuum in the system.
4. 4. With the engine switched off and all vacuum in the system exhausted, appl y the brake pedal and hold it down.
Start the engine. If the vacuum system is operating, the brake pedal will tend to move downward under constant
foot pressure. If no motion is felt, the vacuum booster system is not functioning.
5. 5. Remove the vacuum hose from the brake booster. Manifold vacuum should be available at the brake booster end
of the hose with the engine at idle speed and the transm ission in PARK or NEUTRAL. Make sure that all unused
vacuum outlets are correctly capped, hose connectors are correctly secured and vacuum hoses are in good
condition. When it is established that manifold vacuum is available to the brake booster, connect the vacuum hose
to the brake booster and repeat Step 3. If no downward movement of the brake pedal is felt, install a new brake
booster.
6. 6. Operate the engine for a minimum of 10 seconds at a fast idle. Stop the engine and allow the vehicle to stand for
10 minutes. Then, apply th e brake pedal with approximately 89 N ( 20lb) of force. The pedal feel (brake
application) should be the same as that noted with the engine running. If the brake pedal feels hard (no power
assist), install a new valve and then re peat the test. If the brake pedal still feels hard, in stall a new brake booster.
If the brake pedal movement feels spongy, bleed the brak e system. For additional information, refer to General
Procedures in this section.
Bra k
e Master Cylinder
Usual
l
y, the first and strongest
indicator of anything wrong in the brake syst em is a feeling through the brake pedal. In
diagnosing the condition of the brake master cylinder, check pedal feel as evidence of a brake concern. Check for brake
warning lamp illumination and the brake fluid le vel in the brake master cylinder reservoir.
Normal Conditio
ns
The fo
llowing conditions are considered norm
al and are not indications that the brake master cylinder is in need of repair.
New bra
ke systems are designed to produc
e a pedal effort that is not as hard as in the past. Complaints of light
pedal efforts should be compared to the pedal effort s of another vehicle of the same model and year.
The fl
uid level will fall with brake pad wear.
Abnormal Conditions
•

NOTE: Prior to carrying out any diag
nosis, make sure the brake system warning indicator is functional.
Changes in the brake pedal feel or brake pedal travel are in dicators that something could be wrong in the brake system. The
diagnostic procedure and techniques use brake pedal feel, warning indicator illu mination and low brake fluid level as
indicators to diagnosing brake system co ncerns. The following conditions are cons idered abnormal and indicate that the
brake master cylinder is in need of repair:
Brake ped a
l goes down fast. Th
is could be caused by an ex ternal or internal leak.
Brake pedal goes down slowly
. This could be
caused by an internal or external leak.
Brak
e pedal is low or feels spongy. This condition may be ca
used by no fluid in the brake master cylinder, reservoir

Front Disc Brake - Brake CaliperVehicles
With: Standard Brakes
Re
moval and Installation
Remov

al
W
ARNING: BRAKE DUST, IF INHALED CAN DAMAGE YOUR
HEALTH. ALWAYS REMOVE BRAKE DUST USING A VACUUM
BRUSH. DO NOT USE A COMPRESSED-AIR LINE TO DISPERSE BRAKE DUST INTO THE ATMOSPHERE.
• CAUTIONS:
Replacement of nuts and bolts: Various thread-locking de vices are used on nuts and bolts throughout the vehicle.
These devices restrict the number of times a nut or bolt can be used. See section 100-00 for information.
Remove brake fluid spilla ge immediately from paint work, with clean water.
A new brake hose must be installe d when replacing a brake caliper.
The brake pad adhesive backing must not be reused, therefore always install new brake pads, irrespective of the
condition of the original pads when replacing a brake caliper. Always replace brake pads as an axle set.
S
pecial Tool(s)

Brake Pedal

Hold Tool
JDS 9013
1. O
pen engine compartment and fit
paint work protection covers
to fenders.
2. Raise vehicle on a four-post lift.
3. Raise front of vehicle and support on stands. Refer to Section
100-02.
4. Remove front wheels. See Section 204-04.

5. NOTE
: The following three pictorial procedures must be
carried-out to minimize brake fl uid loss when disconnecting the
brake hose.
Open Left-Hand-Front and Left-H and-Rear caliper bleed nipples.
Connect
a bleed tube and co
ntainer to the calipers.
O
pen bleed nipples.
6. Depress and hold down brak e pedal at the specified
measurement using special tool.
1. Position tool between brake pedal and seat frame.
2. Turn the tool wheel unti l the brake pedal is held

Front Disc Brake - Brake CaliperVehicles With: High Performance Brakes
Re
moval and Installation
Remov

al
S
pecial Tool(s)

Brake Pedal

Hold Tool
JDS 9013
1. WARNING: BRAKE DUST, IF INHALED CAN DAMAGE
YOUR HEALTH. ALWAYS REMOVE BRAKE DUST USING A VACUUM
BRUSH. DO NOT USE A COMPRE SSED-AIR LINE TO DISPERSE
BRAKE DUST INTO THE ATMOSPHERE.
• CAUTIONS:
Replacement of nuts and bolts: Various thread-locking
devices are used on nuts and bolts throughout the vehicle. These
devices restrict the number of ti mes a nut or bolt can be used.
See section 100-00 for information.
Remove brake fluid spillage immediately from paint work,
with clean water.
The Brembo caliper is aligned to the brake disc when it is
first installed to the vehicle, therefore, care must be taken not to
disturb this alignment. When removing the caliper; remove the
bolts that secure the anchor bracket to the vertical link only. DO
NOT loosen any other caliper bolts.
Open engine compartment and fit paint work protection covers
to fenders.
2. R
aise vehicle on a four-post lift.
3. Raise front of vehicle and support on stands. Refer to Section
100-02.
4. Remove front wheels. Refe r to operation 74.20.05.

5. NOTE
: The following three pictorial procedures must be
carried-out to minimize brake fl uid loss when disconnecting the
brake hose.
Open Left-Hand-Front and Left-H and-Rear caliper bleed nipples.
Connect
a bleed tube and co
ntainer to the calipers.
O
pen bleed nipples.
6. Depress and hold down brak e pedal at the specified
measurement using the special tool.

Front Dis
c Brake - Brake DiscVe
hicles With: Standard Brakes
Re
moval and Installation
Remov

al
• WAR
NINGS:
BRAKE DISCS MUST ALWAYS BE REPLACED IN PAIRS.
BRAKE DUST, IF INHALED CAN DAMAGE YOUR HEALTH. ALWAYS REMOVE BRAKE DUST USING A VACUUM BRUSH.
DO NOT USE A COMPRESSED-AIR LINE TO DI SPERSE BRAKE DUST INTO THE ATMOSPHERE.
CAUTION: Replacement of nuts and bolts: Various thread-locking devices are used on nuts and bolts throughout the
vehicle. These devices restrict the number of times a nut or bolt can be used. See section 100-00 for information.
1. O
pen engine compartment and in
stall paint work protection
covers to fenders.
2. Raise front of vehicle and suppo rt on stands. See Section 100-
02.
3. Remove front wheels. Re fer to Section 204-04.

4. CAUTI
ON: Remove brake flui
d spillage immediately from
paint work, with clean water.
Loosen brake fluid reservoir-cap.
Position a cloth around the
reservoir to collect any fluid
spillage.

5. CAU
TION: Tie caliper housing aside. Do not allow the
caliper housing to hang on the hydraulic hose, as this will damage
the hose.
Remove caliper housing from caliper carrier.
1. Remove anti-rattle spring.
2. Remove dust covers.
3. Remove guide pins.
Re
move and tie caliper housing aside.
6.
CAUTI
ON: Always install new brake pads, irrespective of
the condition of the original pads, when renewing brake discs.
• NOTE: The inner brake pad is fitted with a clip which secures
the pad into the caliper piston.
Remove brake pads from caliper housing.

Front Dis
c Brake - Brake PadsVe
hicles With: Standard Brakes
Re
moval and Installation
Remov

al
W
ARNING: BRAKE DUST, IF INHALED CAN DAMAGE YOUR
HEALTH. ALWAYS REMOVE BRAKE DUST USING A VACUUM
BRUSH. DO NOT USE A COMPRESSED-AIR LINE TO DISPERSE BRAKE DUST INTO THE ATMOSPHERE.
CAUTION: Replacement of nuts and bolts: Various thread-locking devices are used on nuts and bolts throughout the
vehicle. These devices restrict the number of times a nut or bolt can be used. See section 100-00 for information.
1. O
pen engine compartment and fit
paint work protection covers
to fenders.
2. Raise front of vehicle and suppo rt on stands. See Section 100-
02.
3. Remove front wheels. See Section 204-04.

4. CAUTI
ON: Remove brake flui
d spillage immediately from
paint work, with clean water.
Loosen brake fluid reservoir-cap.
Position a cloth around the
reservoir to collect any fluid
spillage.

5. CAU
TION: Tie caliper housing aside. Do not allow the
caliper housing to hang on the hydraulic hose, as this will damage
the hose.
Remove caliper housing from caliper carrier.
1. Remove anti-rattle spring.
2. Remove dust covers.
3. Remove guide pins.
Re
move and tie caliper housing aside.

6.
NO
TE: The inner brake pad is fitt
ed with a clip which secures
the pad into the caliper piston.
Remove brake pads from caliper housing.
Discard
brake pads.
7. Clean all mating surfaces and remove brake dust, see
WARNING above.

Rear Disc Brake - Brake CaliperVehicles W
ith: Standard Brakes
Re
mo
val and Installation
Remov
a
l
WA
RNING: BRAKE DUST, IF INHALED CAN DAMAGE YOUR
HEALTH. ALWAYS REMOVE BRAKE DUST USING A VACUUM
BRUSH. DO NOT USE A COMPRESSED-AIR LINE TO DISPERSE BRAKE DUST INTO THE ATMOSPHERE.
• CAUTIONS:
Replacement of nuts and bolts: Various thread-locking de vices are used on nuts and bolts throughout the vehicle.
These devices restrict the number of times a nut or bolt can be used. See section 100-00 for information.
Remove brake fluid spilla ge immediately from paint work, with clean water.
The brake pad adhesive backing must not be reused, therefore always install new brake pads, irrespective of the
condition of the original pads when replacing a brake caliper. Always replace brake pads as an axle set.
Sp
ecial Tool(s)

Brake Pedal
H
old Tool
JDS 9013
1. Op
en luggage compartment lid and fit suitable paintwork
protection equipment.
2. Raise vehicle on a four-post lift.
3. Raise rear of vehicl e and support on stan ds. See Section 100-
02.
4. Remove rear wheel. See Section 204-04.

5. NOTE
: Th
e following three pictorial procedures must be
carried-out to minimize brake fl uid loss when disconnecting the
brake hose.
Open Left-Hand-Front and Left-H and-Rear caliper bleed nipples.
Connect a
bleed tube and co
ntainer to the calipers.
Op
en bleed nipples.
6. Depress and hold down brak e pedal at the specified
measurement using the special tool.
1. Position tool between brake pedal and seat frame.
2. Turn the tool wheel unti l the brake pedal is held
60mm down from its released position.