1998 JAGUAR X308 brake vacuum

Install peda
l housing to vehicle.
Make sure ped

al housing apertu
re is positioned correctly.
Inst
all and tighten nuts to 15-20 Nm.
3. Position cloth underneath master cylinder to collect brake fluid
spillage.

4. Inst
all brake tubes to master cylinder.
Re

move plugs.
Connect

and tighten brake tubes. Refer to Specification
section 206-06 for torque setting.
R
emove cloth from underneath master cylinder.

5. Con
nect throttle cabl
e to pedal housing.
Inst
all cable to grommet.
Inst

all cable to
pedal housing.

6. Conne
ct throttle inner ca
ble to pedal grommet.
7. Connect vacuum pipe elbow to brake booster.
1. Install new seal.
2. Connect pipe.

8. Conne ct
low-level warning connector to master cylinder.

9. Inst al
l cruise control vacuum-valves, mounting bracket.
Install and tigh
ten bolts.

10 . Conne
ct stop lamp switch connector.
Conne
ct
connector.
Re
posi
tion carpet.
11. Connect battery ground cable (IMPORTANT, see operation
86.15.15 for further information).
12. Bleed brake system. See operation 70.25.03.
13. Install engine compartment rear cover. Refer to operation
76.11.35.
14. Remove paint-work protection covers and close engine
compartment.

15 . Conne
ct battery ground cable (I
MPORTANT, refer to operation
86.15.19 for further information).

Power Brake Actuation - Brake Booster
Description and Operation


The brake b
ooster provides assi
stance by reinforcing the driver's effort when brakin g. The reinforced assistance
provided by the booster is proportional to the driver's effort applied to the brake pedal.
The brake force applied by
the driver is incr
eased by the booster in a ratio of 6.5:1.
Th
e vacuum used to operate the booster
is formed in the engine's intake manifold. The booster is connected to the
intake manifold by a hose.
The boost
er is fail-safe therefore, if a fault develops in
the vacuum unit, the braking system will still function.
However, the driver will have to apply a greater fo rce to the brake pedal to slow down the vehicle.


It e
m
Par
t
Number
De
scr
iption
1—Mas
t
er Cylinder / Reservoir - refer to 206-06
2—Booster

3—Pedal Box
- refer to 206-06
4—Vacuu
m
Hose
5—No
n
-Return Valve

56. Disconnect the fuel feed and return hoses.
1. Disconnect the fuel hoses at the Quick Fit connectors,
using special tool 310 - 044 for the feed hose and
310 - 54 for the return hose.
Disconnect the return hose from the feed hose clip.
Fit blanking plugs to the pipes.

57. Disconnect the pipes from the purge valve.
1. Remove the clip which secu res the part load breather
hose to the purge valve.
2. Disconnect the part load breather hose.
3. Disconnect the vacuum hose from the purge valve and reposition the hose.

58. Disconnect the throttle cable.
1. Secure the cable abutment to the bracket with tape or a ratchet strap, if nece ssary (to save subsequent
adjustment procedure). Remove the bolts which
secure the abutment bracke t to the throttle body.
2. Rotate the butterfly actuator cam and disconnect the cable. Reposition the cable.
59. Disconnect the heater and brake servo hoses.
1. Disconnect the he ater return hose.
2. Release the heater feed hose locking lever and
disconnect the hose.

the
intake elbow provide connections for vacuum actuators and are also used to redirect emissions into the engine.
On the right-hand side of the elbow a la rge diameter pipe connects to the brake servo. The smaller pipe provides a vacuum
feed to the fuel rail pressure regulator and throttle cruise control system. On the le ft-hand side of the elbow the front pipe
supplies vacuum control for the evaporative emissions system valves.
Emissions from the engine part load breather (bank 2) and pu rged fuel vapor from the EVAP valve are drawn via a common
T piece into the left-hand side of the intake elbow. Re-cir culated exhaust gas enters the intake elbow via the EGR valve
which is mounted directly on the rear of the elbow : where the EGR system is not used, a blanking plate is fitted.
The fuel system, throttle and emission control system s are described more fully in the relevant sections.
Intake Manifold

Filtered air from the vehicle's intake ducting is metered by th e electronic throttle and distributed to the two cylinder banks
via an integral intake manifold.
The intake manifold is manufactured in plastic with integral plastic fuel rails and metal-thread inserts; the very smooth
internal surfaces give excellent air flow.
Individual ducts lead off a central chamber to the inlet valves of each cylinder.
Silicon-rubber gaskets, loca ted in channels in the intake manifold, seal th e joints between the ducts and the cylinder heads.
Engine Ventilation

The e
ngine is ventilated through two brea
thers; a part-load breather and a full-load breather, one on each camshaft cover.
The outlet hose for the part-load breather is connected between the bank 2 camshaft cover and the intake elbow. The full-
load outlet hose is connected from the bank 1 camshaft cover to the intake duct between the MAF sensor assembly and the
throttle body.
Constructed in plastic, the hoses incorporate O-ring seal s and quick-release connectors; refer to Section 303-01.
I
ntake Air Distribution and Filtering - Supercharged Vehicles
Ai
r is supplied to the supercharger via an
intake cleaner/duct, throttle assembly and intake elbow which are similar to those
used for normally aspirated engines. The su percharger delivers pressurized air to two separate charge air cooler units, each
unit being mounted on the cy linder bank which it supplies. Pr essurized cooled air is fed from the charge air coolers directly
into each inlet port.

The intake elbow di
rects the metered airflow from the electronic throttle outlet (und
erside of the throttle body) into the
intake of the supercharger.
The supercharger by-pass valve assembly is bolted to the intake elbow. The butterfly valve inside the assembly is opened
by a diaphragm actuator operated by vacu um feed from the elbow. At closed or partially open throttle positions, the
butterfly valve opens, allowing th e airflow from the two charge air cooler inlets to be directed back to the supercharger inlet .
This action inhibits the supercharging e ffect and reduces engine torque to non supercharged levels. Progressive opening of
the throttle causes the by-pass valve to gradually close.
On the right-hand side of the elbow a la rge diameter pipe connects to the brake servo. On the left-hand side the smaller
pipe supplies vacuum control for the evaporative emissions system valves.
Emissions from the engine part load breather (bank 1) and pu rged fuel vapor from the EVAP valve are drawn via a common
T piece into the left-hand side of the intake elbow. Re-cir culated exhaust gas enters the intake elbow via the EGR valve
which is mounted directly on the rear of the elbow. Where the EGR system is not used, a blanking plate is fitted.
The fuel system and emission control systems are described more fully in the relevant sections.
Fuel Pressure Regula
tion and
Cruise Control Vacuum Feed
The inlet v
acuum feed fo
r the fuel rail pressure regula tor and the cruise control system is taken from the supercharger
outlet duct. The feed pipe is located below the large charge air cooler coolant filler plug.
Superchar
ger
and associated components
Inta
ke Elbow and Bypass

Intake Air Distribution and Filtering - Thrott
le Body Elbow
Re
mo
val and Installation
Remov
a
l
1.
WARNING: B E
FORE PROCEEDING, IT IS ESSENTIAL THAT

WARNING NOTES GIVEN IN SECTION 100-00 (UNDER HEADING
'SAFETY PRECAUTIONS') AR E READ AND UNDERSTOOD.
Disconnect battery ground cable (IMPORTANT, see SRO
86.15.19 for further information).
2. Re
move air cleaner cover / inta
ke assembly; refer 19.10.30.
3. Remove throttle assemb ly; refer to 19.70.04.
4. Remove exhaust gas recirculation (EGR) valve where installed;
refer 17.45.01.

5. Re
lease intake elbow from right-hand support bracket.
Re
lea
se brake servo vacuum pi
pe and disconnect pipe.
1. Disconnect vacuum pipe.
2. Remove upper bolt.

6. Relea
se intake elbow from le
ft-hand support bracket.
1. Disconnect vacuum pipe.
2. Disconnect engine breather T-piece.
3. Remove upper bolt.
4. Loosen, but do not remove, lower two bolts.

7. Re
move intake elbow from supercharger.
1. Release and pull back cl ips securing bypass hoses
at charge air coolers.
2. Remove four bolts.
3. Remove hoses from charge air cooler stub pipes.
Re move as
sembly from vehicle.
4. Discard gasket.
Cle a
n all mating faces.
8. Remove by-pass valve assembly from intake elbow.

Intake Air Distribution and Filtering - Throt
tle Body Elbow4.0L NA V8 -
AJ27/3.2L NA V8 - AJ26
Re
moval and Installation
Remov

al
S
pecial Tool(s)

Re

lease tool - quick fit
310-044 (JD 182)

R
elease tool 5 /16 - quick fit
310-054 (JD 203)
1. WARNING: BEFORE PROCEEDING, IT IS ESSENTIAL THAT
THE WARNING NOTES GIVEN IN SECTION 100-00 (UNDER THE
HEADING 'SAFETY PRECAUTIONS') ARE READ AND
UNDERSTOOD.
Disconnect battery ground cable (IMPORTANT, see SRO
86.15.19 for further information).
2. D
epressurize fuel sy
stem; refer to 19.50.02
3. Remove air cleaner cover / intake assembly; refer to 19.10.30.
4. Remove throttle body; refer to 19.70.04.

5. R
elease intake elbow from right-hand support bracket.
Re

lease brake servo vacuum pi
pe and disconnect pipe.
1. Disconnect vacuum pipe.
2. Remove bolt.
6. Release intake elbow from le ft-hand support bracket.
1. Disconnect vacuum pipe.
2. Disconnect engine breather T-piece.
3. Remove bolt.
4. Loosen, but do not remove two bolts.