
(8) Check condition of seal at rear of master cylin-
der (Fig. 22). Clean and reposition seal if dislodged.
Replace seal if cut, or torn.
(9) Clean cylinder mounting surface of brake
booster (Fig. 19). Use shop towel wetted with brake
cleaner for this purpose. Dirt, grease, or similar ma-
terials will prevent proper cylinder seating and could
result in vacuum leak.
(10) Position master cylinder on booster studs (Fig.
20).Be sure booster push rod is centered and
seated in master cylinder piston shank.
(11) Install and tighten master cylinder attaching
nuts to 25 Nzm (220 in. lbs.) torque.(12) Install HCU as follows:
(a) If only the HCU was removed, position HCU
in mounting bracket. Then install and tighten
three shoulder bolts that attach HCU to bracket
(Figs. 21 and 22). One bolt is used at forward end
of bracket and two at rear as shown.
(b) If HCU and bracket were removed as assem-
bly, position bracket on studs and install attaching
nuts. Tighten nuts to 10-13 Nzm (92-112 in. lbs.)
torque.
(c) On right hand drive models, If brackets were
removed, assemble brackets. Then position lower
bracket on body studs and install attaching nuts
and the one attaching bolt (Fig. 23).
(13) If HCU mounting bracket was not removed,
press solenoid harness connecter fasteners into
mounting bracket holes.
(14) Connect HCU pump motor and solenoid har-
nesses (Figs. 13 and 14).
(15) Connect brakelines to HCU. Start brakeline
fittings in HCU ports by hand to avoid cross thread-
ing (Fig. 24). Then tighten line fittings snug but not
to required torque at this time.
Fig. 18 Checking Master Cylinder Seal
Fig. 19 Cylinder Mounting Surface Of Brake Booster
Fig. 20 Master Cylinder Installation
Fig. 21 Installing HCU Front Shoulder Bolt
Fig. 22 Installing HCU Rear Shoulder Bolts
5 - 28 POWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCHJ

(16) Install combination valve as follows:
(a) Work combination valve and brakelines into
position.
(b) Slide combination valve bracket onto booster
stud closest to driver side fender (Fig. 25). Then in-
stall bracket attaching nut but do not fully tighten
nut at this time.
(c) Connect flex lines to HCU. Start lines by
hand to avoid cross threading.
(17) Swing rear brakeline around and connect it to
master cylinder. Then install and connect front
brakeline to combination valve and master cylinder.
Start brakelines by hand to avoid cross threading.
(18) Tighten combination valve bracket attaching
nut to 25 Nzm (220 in. lbs.) torque.
(19) Install clip on lines from master cylinder to
combination valve.
(20) Connect wire to pressure differential switch
on combination valve.
(21) Connect flex lines to HCU (Fig. 10). Start line
fittings by hand to avoid cross threading. Then
tighten fittings snug but not to required torque at
this time.(22) Bleed brakes. Refer to procedure in Brake
Fluid-Brake Bleeding-Brakelines And Hoses section.
(23) Tighten brakeline fittings to 15-18 Nzm (130-
160 in. lbs.) at HCU and master cylinder, and 18-24
Nzm (160-210 in. lbs.) at combination valve.
(24) Install air cleaner assembly.
(25) Connect vacuum lines to manifold fittings.
(26) Check brake pedal action before moving vehi-
cle. Bleed brakes again if pedal is not firm (feels soft/
spongy).POWER BRAKE BOOSTER REMOVAL (XJ WITHOUT
ABS)
(1) Disconnect vent and vacuum hose from engine
air cleaner cover.
(2) Remove engine air cleaner cover, filter, housing
and hoses (Fig. 4).
(3) Disconnect brakelines at master cylinder.
(4) Disconnect wire at combination valve differen-
tial pressure switch.
(5) If combination valve does not have an integral
bracket, disconnect brakelines at combination valve
and remove valve.
(6) If combination valve has integral bracket, re-
move nut attaching valve bracket to booster studs
and remove valve.
(7) Remove nuts attaching master cylinder to
booster studs and remove cylinder.
(8) Disconnect vacuum hose from booster check
valve.
(9) In passenger compartment, remove instrument
panel lower trim cover.
(10) Remove retaining clip that secures booster
push rod to brake pedal (Fig. 5).
Fig. 23 HCU And Bracket Mounting (RHD Models)
Fig. 24 Starting Brakelines In HCU
Fig. 25 Combination Valve Installation
JPOWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCH 5 - 29

(11) Remove nuts attaching booster to passenger
compartment side of dash panel.
(12) In engine compartment, slide booster studs
out of dash panel, tilt booster upward, and remove
booster from engine compartment.
(13) Remove dash seal from booster.
(14) If booster is only being removed for access to
other components, cover booster front opening with
clean shop towel.
POWER BRAKE BOOSTER INSTALLATION (XJ
WITHOUT ABS)
(1) If original booster is being installed, test check
valve with vacuum tool before booster installation.
Replace check valve if it will not hold vacuum.
(2) Install dash seal on booster.
(3) Align and position booster on dash panel (Fig.
17).
(4) In passenger compartment, install nuts that at-
tach booster to dash panel. Tighten nuts just enough
to hold booster in place.
(5) Slide booster push rod onto brake pedal. Then
secure push rod to pedal pin with retaining clip.
(6) Tighten booster attaching nuts to 41 Nzm (30 ft.
lbs.) on XJ and 34 Nzm (25 ft. lbs.) on YJ.
(7) Install instrument panel lower trim cover.
(8) If original master cylinder is being installed,
check condition of seal at rear of master cylinder
(Fig. 18). Clean and reposition seal if dislodged. Re-
place seal if cut, or torn.
(9) Clean cylinder mounting surface of brake
booster. Use shop towel wetted with brake cleaner for
this purpose. Dirt, grease, or similar materials will
prevent proper cylinder seating and could result in
vacuum leak.
(10) Align and install master cylinder on booster
studs. Tighten cylinder attaching nuts to 13-25 Nzm
(115-220 in. lbs.) torque.
(11) Connect vacuum hose to booster check valve.
(12) Connect and secure brakelines to combination
valve and master cylinder. Start all brakeline fittings
by hand to avoid cross threading.
(13) If combination valve has integral bracket, po-
sition bracket on booster studs. Then install and
tighten bracket attaching nuts to 13-25 Nzm (115-220
in. lbs.) torque.
(14) Connect wire to combination valve switch.
(15) Top off master cylinder fluid level.
(16) Bleed brakes. Refer to procedures in section
on brake bleeding.
(17) Install engine air cleaner and hoses.
(18) Verify proper brake operation before moving
vehicle.
POWER BRAKE BOOSTER REMOVAL (YJ)
(1) Disconnect brakelines at master cylinder. Then
loosen lines at combination valve and move lines
away from cylinder.
(2) Remove nuts master cylinder to booster studs.
(3) If combination valve has integral bracket, slide
bracket off studs and move valve aside.
(4) Remove master cylinder. Slide cylinder off
studs and remove it from engine compartment.
(5) Working under instrument panel, remove re-
tainer clip that secures booster push rod to brake
pedal.
(6) Disconnect vacuum hose at booster check valve.
(7) On non-ABS models, remove nuts attaching
brake booster spacer to dash panel and remove
booster (Fig. 26).
(8) On ABS models, remove nuts attaching booster
to spacer and remove booster (Fig. 27).
POWER BRAKE BOOSTER INSTALLATION (YJ)
(1) Install seal on booster spacer, if equipped.
(2) Position booster on dash panel, or on spacer.
(3) Secure booster push rod to brake pedal with re-
taining clip.
(4) Install and tighten booster attaching nuts to
27-47 Nzm (20-35 ft. lbs.) torque. Nut torque applies
to both styles of booster.
Fig. 26 Booster Mounting (4-Cyl. Models)
Fig. 27 Booster Mounting (With ABS)
5 - 30 POWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCHJ

(5) Connect vacuum hose to brake booster check
valve.
(6) Install master cylinder and combination valve.
(7) Bleed brakes. Then tighten brakeline fittings to
15-18 Nzm (130-160 in. lbs.) at master cylinder and
18-24 Nzm (160-210 in. lbs.) at combination valve.
BRAKE PEDAL REMOVAL
(1) Remove lower trim panel and A/C duct if nec-
essary.
(2) Remove steering column lower trim panel and
bezel.(3) Remove necessary dash panel-to-instrument
panel brace rods.
(4) Disconnect and remove brakelight switch.
(5) Remove retainer clip securing booster push rod
to pedal (Fig. 16).
(6) Remove nut securing pedal shaft in support
bracket.
(7) Slide pedal shaft outward for clearance and re-
move brake pedal (Figs. 28 and 29).
(8) Remove pedal bushings if they are to be re-
placed.
BRAKE PEDAL INSTALLATION
(1) Install new bushings in pedal. Lubricate bush-
ings and pivot pin with Mopar multi mileage grease.
(2) Position pedal, sleeve and spacer(s) in bracket
and install pivot pin.
(3) Install new nut on pivot pin.Pivot pin nut is
specially formed and should not be reused. Be
sure to install new nut to secure pin.
(4) ) Tighten new pivot pin nut to 27 Nzm (20 ft.
lbs.) on models with manual transmission. Tighten
nut to 35 Nzm (26 ft. lbs.) on models with automatic
transmission.
(5) Install booster push rod on pedal pin (Fig. 16).
Secure push rod with original, or new retainer clip if
necessary.
(6) Install and connect brakelight switch.
(7) Install dash brace rod, if equipped.
(8) Install instrument panel and steering column
trim covers.
Fig. 28 Brake Pedal And Support Bracket (YJ)
Fig. 29 Brake Pedal And Support Bracket (XJ)
JPOWER BRAKE BOOSTERÐBRAKE PEDALÐBRAKELIGHT SWITCH 5 - 31

HCU INSTALLATION (XJ)
(1) Install HCU as follows:
(a) If only the HCU was removed, position HCU
in mounting bracket. Then install and tighten
three shoulder bolts that attach HCU to bracket
(Figs. 23 and 24). One bolt is used at forward end
of bracket and two at rear as shown.
(b) If HCU and bracket were removed as assem-
bly, position bracket on studs and install attaching
nuts. Tighten nuts to 10-13 Nzm (92-112 in. lbs.)
torque.
(c) On right hand drive models, If brackets were
removed, assemble brackets. Then position lower
bracket on body studs and install attaching nuts
and the one attaching bolt (Fig. 25).
(2) If HCU mounting bracket was not removed,
press solenoid harness connecter fasteners into
mounting bracket.
(3) Connect HCU pump motor and solenoid har-
nesses (Figs. 19 and 20).
(4) Connect brakelines from front/rear brakes to
HCU. Start brakeline fittings in HCU ports by handto avoid cross threading (Fig. 26). Then tighten line
fittings snug but not to required torque at this time.
(5) Connect flex lines to HCU (Fig. 18). Start
brakeline fittings in flex line ports by hand to avoid
cross threading. Then tighten line fittings snug but
not to required torque at this time.
(6) Bleed brakes. Refer to procedure in Brake Flu-
id-Brake Bleeding-Brakelines And Hoses section.
(7) Tighten brakeline fittings to following torques
after brake bleeding: 15- 18 Nzm (130-160 in. lbs.) at
HCU and master cylinder and 18-24 Nzm (160-210 in.
lbs.) at combination valve.
(8) Install engine air cleaner assembly and hoses.
(9) Connect vacuum lines to manifold fittings.
(10) Check brake pedal action before moving vehi-
cle. Bleed brakes again if pedal is not firm (feels soft/
spongy).
Fig. 23 Installing HCU Front Shoulder Bolt
Fig. 24 Installing HCU Rear Shoulder Bolts
Fig. 25 HCU And Bracket Mounting (RHD Models)
Fig. 26 Starting Brakelines In HCU (By Hand)
JABS OPERATION AND SERVICE 5 - 43

CLUTCH SERVICE
INDEX
page page
Clutch Component Lubrication................ 10
Clutch Cover and Disc Installation............. 10
Clutch Cover and Disc Removal.............. 10
Clutch Fluid Level......................... 14
Clutch Housing Replacement................ 13
Clutch Hydraulic Linkage Installation........... 14
Clutch Hydraulic Linkage Removal............. 13Clutch Pedal Installation.................... 15
Clutch Pedal Removal...................... 15
Clutch Safety Precautions................... 10
Flywheel Service.......................... 16
Pilot Bearing Replacement.................. 12
Release Bearing Replacement................ 11
CLUTCH SAFETY PRECAUTIONS
WARNING: EXERCISE CARE WHEN SERVICING
CLUTCH COMPONENTS. DUST AND DIRT ON
CLUTCH PARTS USE MAY CONTAIN ASBESTOS FI-
BERS. BREATHING EXCESSIVE CONCENTRATIONS
OF THESE FIBERS CAN CAUSE SERIOUS BODILY
HARM. WEAR A RESPIRATOR DURING SERVICE
AND NEVER CLEAN CLUTCH COMPONENTS WITH
COMPRESSED AIR OR WITH A DRY BRUSH. EI-
THER CLEAN THE COMPONENTS WITH A WATER
DAMPENED RAGS OR USE A VACUUM CLEANER
SPECIFICALLY DESIGNED FOR REMOVING ASBES-
TOS FIBERS AND DUST. DO NOT CREATE DUST BY
SANDING A CLUTCH DISC. REPLACE THE DISC IF
THE FRICTION MATERIAL IS DAMAGED OR CON-
TAMINATED. DISPOSE OF ALL DUST AND DIRT
CONTAINING ASBESTOS FIBERS IN SEALED BAGS
OR CONTAINERS. THIS WILL HELP MINIMIZE EX-
POSURE TO YOURSELF AND TO OTHERS. FOL-
LOW ALL RECOMMENDED SAFETY PRACTICES
PRESCRIBED BY THE OCCUPATIONAL SAFETY
AND HEALTH ADMINISTRATION (OSHA) AND THE
ENVIRONMENTAL SAFETY AGENCY (EPA), FOR
THE HANDLING AND DISPOSAL OF PRODUCTS
CONTAINING ASBESTOS.
CLUTCH COMPONENT LUBRICATION
Proper clutch component lubrication is important
to satisfactory operation. Using the correct lubricant
and not overlubricating are equally important. Apply
recommended lubricant sparingly to avoid disc and
pressure plate contamination.
Clutch and transmission components requiring lu-
brication are:
²pilot bearing
²release lever pivot ball stud
²release lever contact surfaces
²release bearing bore
²clutch disc hub splines
²clutch pedal pivot shaft bore
²clutch pedal bushings²input shaft splines
²input shaft pilot hub
²transmission front bearing retainer slide surface
Never apply grease to any part of the clutch
cover, or disc.
Recommended Lubricants
Use Mopar multi-purpose grease for the clutch
pedal bushings and pivot shaft. Use Mopar high tem-
perature grease (or equivalent) for all other lubrica-
tion requirements. Apply recommended amounts and
do not overlubricate.
CLUTCH COVER AND DISC REMOVAL
(1) Remove transmission. Refer to procedures in
Group 21.
(2) If original clutch cover will be reinstalled, mark
position of cover on flywheel for assembly reference.
Use paint or a scriber for this purpose.
(3) If clutch cover is to be replaced, cover bolts can
be removed in any sequence. However, if original
cover will be reinstalled, loosen cover bolts evenly
and in rotation to relieve spring tension equally. This
is necessary avoid warping cover.
(4) Remove cover bolts and remove cover and disc
(Fig. 2).
CLUTCH COVER AND DISC INSTALLATION
(1) Lightly scuff sand flywheel face with 180 grit
emery cloth. Then clean surface with a wax and
grease remover.
(2) Lubricate pilot bearing with Mopar high tem-
perature bearing grease.
(3) Check runout and free operation of new clutch
disc as follows:
(a) Slide disc onto transmission input shaft
splines. Disc should slide freely on splines.
(b) Leave disc on shaft and check face runout
with dial indicator. Check runout at disc hub and
about 6 mm (1/4 in.) from outer edge of facing.
(c) Face runout should not exceed 0.5 mm (0.020
in.). Obtain another clutch disc if runout exceeds
this limit.
6 - 10 CLUTCH SERVICEJ

CAUTION: Do not operate the engine with a spark
plug shorted for more than a minute. The catalytic
converter may be damaged.
Isolate the compression leak by shorting each
spark plug to the cylinder block. The gauge pointer
should stop or decrease vibration when spark plug
for leaking cylinder is shorted. This happens because
of the absence of combustion pressure.
COMBUSTION LEAKAGE TEST (WITHOUT
PRESSURE TESTER)
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.
Drain sufficient coolant to allow for thermostat re-
moval. Refer to Thermostat Replacement. Disconnect
the water pump drive belt.
Disconnect the upper radiator hose from the ther-
mostat housing. Remove the housing and thermostat.
Install the thermostat housing.
Add coolant to the radiator to bring the level to
within 6.3 mm (1/4 in) of the top of the thermostat
housing.
CAUTION: Avoid overheating. Do not operate the
engine for an excessive period of time. Open the
draincock immediately after the test to eliminate
boil over of coolant.
Start the engine and accelerate rapidly three times
(to approximately 3000 rpm) while observing the
coolant. If internal engine combustion gases are leak-
ing into the cooling system, bubbles will appear in
the coolant. If bubbles do not appear, there is no in-
ternal combustion gas leakage.
COOLANT RESERVE/OVERFLOW SYSTEM
The system works along with the radiator pressure
cap. This is done by using thermal expansion and
contraction of the coolant to keep the coolant free of
trapped air. It provides:
²A volume for coolant expansion and contraction.
²A convenient and safe method for checking/adjust-
ing coolant level at atmospheric pressure. This is
done without removing the radiator pressure cap.
²Some reserve coolant to the radiator to cover mi-
nor leaks and evaporation or boiling losses.
As the engine cools, a vacuum is formed in the
cooling system of both the radiator and engine. Cool-ant will then be drawn from the coolant tank and re-
turned to a proper level in the radiator.
The coolant reserve/overflow system consists of a
radiator mounted pressurized cap, a plastic reserve/
overflow tank (Figs. 22, 23 or 24), a tube (hose) con-
necting the radiator and tank, and an overflow tube
on the side of the tank.
Fig. 22 Reserve/Overflow TankÐYJ Models
Fig. 23 Reserve/Overflow TankÐXJ ModelsÐExcept
Right Hand Drive
7 - 24 COOLING SYSTEM SERVICE PROCEDURESJ

TANK REMOVAL/INSTALLATION
(1) Remove the tube clamp at the tank and remove
tube.
(2) On YJ models, remove the windshield washer
reservoir and its mounting bracket.
(3) Remove the tank mounting bolts and remove
tank.
(4) Reverse the preceding steps for installation.
RADIATOR PRESSURE CAP
All radiators are equipped with a pressure cap.
This cap releases pressure at some point within a
range of 83-110 kPa (12-16 psi). The pressure relief
point (in pounds) is engraved on top of the cap (Fig.
25).
The cooling system will operate at pressures
slightly above atmospheric pressure. This results in a
higher coolant boiling point allowing increased radi-
ator cooling capacity. The cap (Fig. 25) contains a
spring-loaded pressure relief valve. This valve opens
when system pressure reaches the release range of
83-110 kPa (12-16 psi).
A vent valve in the center of the cap allows a small
coolant flow through the cap when coolant is below
boiling temperature. The valve is completely closed
when boiling point is reached. As coolant cools, it
contracts and creates a vacuum in the cooling sys-
tem. This causes the vacuum valve to open and cool-
ant in reserve/overflow tank to be drawn through
connecting hose into radiator. If the vacuum valve is
stuck shut, radiator hoses will collapse on cool-down.A rubber gasket seals the radiator filler neck. This
is done to maintain vacuum during coolant cool-down
and to prevent leakage when system is under pres-
sure.RADIATOR CAP-TO-FILLER NECK SEALÐ
PRESSURE RELIEF CHECK
With radiator cap installed on filler neck, remove
coolant reserve/ overflow tank hose from nipple on
filler neck. Connect a hand operated vacuum pump
to nipple. Operate pump until a reading of 47-to-61
kPa (14-to-18 in. Hg) appears on gauge. If the read-
ing stays steady, or drops slightly and then remains
steady, the pressure valve seal is good. Replace radi-
ator cap if reading does not hold.
WARNING: THE WARNING WORDS -DO NOT OPEN
HOT- ON THE RADIATOR PRESSURE CAP (FIG. 25)
ARE A SAFETY PRECAUTION. WHEN HOT, PRES-
SURE BUILDS UP IN COOLING SYSTEM. TO PRE-
VENT SCALDING OR INJURY, THE RADIATOR CAP
SHOULD NOT BE REMOVED WHILE THE SYSTEM
IS HOT AND/OR UNDER PRESSURE.
There is no need to remove the radiator capex-
ceptfor the following purposes:
(1) To check and adjust antifreeze freeze point.
(2) To refill system with new antifreeze.
(3) For conducting service procedures.
Fig. 24 Reserve/Overflow TankÐXJ ModelsÐWith
Right Hand Drive
Fig. 25 Radiator Pressure Cap
JCOOLING SYSTEM SERVICE PROCEDURES 7 - 25