1988 JEEP CHEROKEE air bleeding

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AN TI- L O CK B RAK E S A FE TY P R EC AU TIO NS

1988 J e ep C hero ke e
GENERAL INFORMATION
Anti-Lock Brake Safety Precautions
* PLEASE READ THIS FIRST *
This article is intended for general information purposes
only. This information may not apply to all makes and models. If
vehicle is equipped with Anti-Lock Brake System (ABS), refer to
appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES section for
description, operation, depressurizing, testing, system bleeding,
trouble shooting and servicing of specific system.
WARNING: Failure to depressurize ABS could lead to physical injury.
ANTI-LOCK BRAKE SAFETY PRECAUTIONS
WARNING: Failure to depressurize ABS could lead to physical injury.
* NEVER open a bleeder valve or loosen a hydraulic line
while ABS is pressurized.
* NEVER disconnect or reconnect any electrical connectors
while ignition is on. Damage to ABS control unit may result.
* DO NOT attempt to bleed hyudarulic system without first
referring to the appropriate ANTI-LOCK BRAKE SYSTEM article
in the BRAKES section.
* Only use specially designed brake hoses/lines on ABS equipped
vehicles.
* DO NOT tap on speed sensor components (sensor, sensor rings).
Sensor rings must be pressed into hubs, NOT hammered into
hubs. Striking these components can cause demagnetization or
a loss of polarization, affecting the accuracy of the speed
signal returning to the ABS control unit.
* DO NOT mix tire sizes. Increasing the width, as long as tires
remain close to the original diameter, is acceptable. Rolling
diameter must be identical for all 4 tires. Some
manufacturers recommend tires of the same brand, style and
type. Failure to follow this precaution may cause inaccurate
wheel speed readings.
* DO NOT contaminate speed sensor components with grease. Only
use recommended coating, when system calls for an
anti-corrosion coating.
* When speed sensor components have been removed, ALWAYS check
sensor-to-ring air gaps when applicable. These specifications
can be found in each appropriate article.
* ONLY use rocommended brake fluids. DO NOT use silicone brake
fluids in an ABS equipped vehicle.
* When instlling transmittion devices (CB's, telephones, etc.)
on ABS equipped vehicles, DO NOT locate the antenna near the
ABS control unit (or any control unit).
* Disconnect all on-board computers, when using electric
welding equipment.
* DO NOT expose the ABS control unit to prolonged periods of
high heat (185
F/85C for 2 hours is generally considered a
maximum limit).

BRAK E S YSTE M B LE ED IN G

1988 J e ep C hero ke e
1988 BRAKES
Jeep - Brake System Bleeding
Cherokee, Comanche, Grand Wagoneer, Wagoneer, Wrangler
BRAKE SYSTEM BLEEDING
Hydraulic system bleeding is necessary any time air has been
introduced into system. Bleed brakes at all 4 wheels if master
cylinder lines have been disconnected or master cylinder has run dry.
Bleed brakes with vacuum bleeding equipment, pressure bleeding
equipment or by manually pumping brake pedal while using bleeder
tubes. Always bleed brake lines in sequence. See BLEEDING SEQUENCE
table.
MASTER CYLINDER BLEEDING
Bench Bleeding
1) Master cylinder must be bled before installation to
prevent excessive amounts of air from entering the brake system,
creating poor brake operation.
2) Place master cylinder in soft-jawed vise. DO NOT tighten
vise enough to damage master cylinder. Install bleeder tubes in both
outlets of master cylinder. See Fig. 1.
Fig. 1: Bleeding Master Cylinder
Courtesy of American Motors/Jeep Corp.
3) Fill master cylinder with clean brake fluid that meets DOT
3 specifications. Ensure that the end of bleeder tubes are submerged

in the brake fluid.
4) Using proper sized rod, apply and release master cylinder
until no air bubbles exist in brake fluid flow. Once all air bubbles
are gone from master cylinder secure cap and install.
5) Bleeder tubes should be left installed on master cylinder
until master cylinder in installed. Master cylinder must be bled at
brake lines and wheels after installation.
Bleeding On Vehicle
1) Install master cylinder on vehicle after bench bleeding.
Remove bleeder lines and install brake lines. DO NOT fully tighten
brake lines at this time.
2) Slowly force brake pedal to the floor and hold in this
position. Tighten brake lines and release brake pedal. Repeat
procedure until no air bubbles exist at brake lines. Remaining wheel
cylinder or calipers may be require bleeding.
HYDRAULIC CONTROL VALVES
Hold Off Valve
1) Prior to the pressure tank bleeding procedure, the hold
off valve incorporated in the combination valve must be correctly
positioned. This allows brake fluid to flow through the combination
valve to the entire brake system.
2) The valve stem of the hold off valve may be retained using
tools available from Chrysler Motors (C-4121) or General Motors
(J-23709) during bleeding procedure. See Figs. 2 and 3. Remove valve
retainer once brake bleeding procedure is complete.
CAUTION: DO NOT use rigid clamp to position valve stem. Damage to
the valve assembly may result causing brake failure.
Fig. 2: Positioning Hold Off Valve
Courtesy of American Motors/Jeep Corp.

All Models ............................... 15-20 (1.1-1.4)








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MANUAL BLEEDING
NOTE: When bleeding disc brakes, air may tend to cling to caliper
walls. Lightly tap caliper, while bleeding, to aid in
removal of air.
1) Fill master cylinder. Install bleeder hose to first
bleeder valve to be serviced. See BLEEDING SEQUENCE table. Submerge
other end of hose in clean glass jar partially filled with clean brake
fluid. See Fig. 4.
2) Open bleeder valve 3/4-1 turn. Depress brake pedal slowly
through full travel. Close bleeder valve and release pedal. Repeat
procedure until flow of fluid shows no signs of air bubbles.
NOTE: When bleeding brake system manually, ensure bleeder valve is
closed when brake pedal is released.
Fig. 4: Wheel Cylinder Bleeding Procedure
Courtesy of American Motors/Jeep Corp.
BLEEDING SEQUENCE

1) Adjust rear brakes. Check cable for binds, kinks or frayed
condition. Replace cable (if necessary). Release parking brake. Loosen\
lock nuts at parking brake cable equalizer under vehicle.
2) Tighten cables until wheels drag slightly when rotated by
hand. Loosen equalizer until wheels rotate freely and no drag is felt.
Tighten lock nuts and check operation of parking brake.
ROTOR SERVICING
RUNOUT
1) Measure rotor lateral runout by mounting a dial indicator
on support stand or steering spindle. Position indicator stylus so it
contacts center of rotor braking surface.
2) Zero indicator and turn rotor one revolution. Note
indicator reading. Runout must not exceed specification. See DISC
BRAKE ROTOR SPECIFICATIONS table. Refinish or replace rotor (if
necessary).
NOTE: Thickness of machined rotor must not be below minimum
thickness specification.
PARALLELISM
Measure rotor parallelism with a micrometer. Measure
thickness at 4 or more equally spaced points around rotor at
approximately 1" from edge of rotor. Variation must not exceed
specification. See DISC BRAKE ROTOR SPECIFICATIONS table. Refinish or
replace rotor (if necessary).
BRAKE SYSTEM BLEEDING
Hydraulic system bleeding is necessary any time air has been
introduced into system. Bleed brakes at all 4 wheels if master
cylinder lines have been disconnected or master cylinder has run dry.
Bleed brakes with vacuum bleeding equipment, pressure bleeding
equipment or by manually pumping brake pedal while using bleeder
tubes. Always bleed brake lines in sequence. See BLEEDING SEQUENCE
table.
MASTER CYLINDER BLEEDING
Bench Bleeding
1) Master cylinder must be bled before installation to
prevent excessive amounts of air from entering the brake system,
creating poor brake operation.
2) Place master cylinder in soft-jawed vise. DO NOT tighten
vise enough to damage master cylinder. Install bleeder tubes in both
outlets of master cylinder. See Fig. 5.

Fig. 5: Bleeding Master Cylinder
Courtesy of American Motors/Jeep Corp.
3) Fill master cylinder with clean brake fluid that meets DOT
3 specifications. Ensure that the end of bleeder tubes are submerged
in the brake fluid.
4) Using proper sized rod, apply and release master cylinder
until no air bubbles exist in brake fluid flow. Once all air bubbles
are gone from master cylinder secure cap and install.
5) Bleeder tubes should be left installed on master cylinder
until master cylinder in installed. Master cylinder must be bled at
brake lines and wheels after installation.
Bleeding On Vehicle
1) Install master cylinder on vehicle after bench bleeding.
Remove bleeder lines and install brake lines. DO NOT fully tighten
brake lines at this time.
2) Slowly force brake pedal to the floor and hold in this
position. Tighten brake lines and release brake pedal. Repeat
procedure until no air bubbles exist at brake lines. Remaining wheel
cylinder or calipers may be require bleeding.
HYDRAULIC CONTROL VALVES
Hold Off Valve
1) Prior to the pressure tank bleeding procedure, the hold
off valve incorporated in the combination valve must be correctly
positioned. This allows brake fluid to flow through the combination
valve to the entire brake system.
2) The valve stem of the hold off valve may be retained using

Fill master cylinder. Install vacuum bleed equipment to first
bleeder valve to be serviced. Open bleeder valve 3/4-1 turn. Depress
vacuum pump and pull fluid into reservoir jar. Bleed each bleeder
valve in sequence. See BLEEDING SEQUENCE table.
PRESSURE BLEEDING
1) Clean master cylinder cap and surrounding area. Remove
cap. With pressure tank at least 1/2 full, connect to master cylinder
with adapters. Attach bleeder hose to first bleeder valve to be
serviced. See BLEEDING SEQUENCE table.
2) Place other end of hose in clean glass jar partially
filled with clean brake fluid so end of hose is submerged in fluid.
The hold off valve must be positioned properly before pressure
bleeding (if equipped). See HYDRAULIC CONTROL VALVES under BRAKE
SYSTEM BLEEDING in this article.
3) Open release valve on pressure bleeder. Follow equipment
manufacturer's pressure instructions or see PRESSURE BLEEDER SETTINGS
table. Open bleeder screw 3/4-1 turn and note fluid flow.
4) Close bleeder screw when fluid flowing is free of bubbles.
Repeat procedure on remaining wheels in proper sequence. Check brake
pedal operation after bleeding has been completed.
5) Remove pressure bleeding equipment and valve retainer from
hold off valve. Ensure that master cylinder is full of fluid.
PRESSURE BLEEDER SETTINGS TABLE









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Application psi (kg/cm)
All Models ............................... 15-20 (1.1-1.4)









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MANUAL BLEEDING
NOTE: When bleeding disc brakes, air may tend to cling to caliper
walls. Lightly tap caliper, while bleeding, to aid in
removal of air.
1) Fill master cylinder. Install bleeder hose to first
bleeder valve to be serviced. See BLEEDING SEQUENCE table. Submerge
other end of hose in clean glass jar partially filled with clean brake
fluid. See Fig. 8.
2) Open bleeder valve 3/4-1 turn. Depress brake pedal slowly
through full travel. Close bleeder valve and release pedal. Repeat
procedure until flow of fluid shows no signs of air bubbles.
NOTE: When bleeding brake system manually, ensure bleeder valve is
closed when brake pedal is released.

PO W ER S TE ER IN G G EN ER AL S ER VIC IN G

1988 J e ep C hero ke e
1988 STEERING
Jeep Power Steering General Servicing
Cherokee, Comanche, Grand Wagoneer, Pickup, Wagoneer,
Wrangler
LUBRICATION
SERVICE INTERVALS
Check fluid at every oil change.
CHECKING FLUID LEVEL
Check fluid level with engine stopped and fluid hot or cold.
Fluid level must be at "FULL-HOT" or "FULL-COLD" mark on dipstick. On
models with remote reservoir, keep fluid level 0.5-1.0" from top of
reservoir with wheels turned fully to left.
RECOMMENDED FLUID TABLE









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Application Part Number
Jeep ............................................. 8993342









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REFILLING & BLEEDING SYSTEM
1) Fill reservoir to correct level. Operate engine until
fluid reaches normal operating temperature. Stop engine. Add fluid (if
necessary). Turn wheels to full left position. Add fluid to reservoir
to fill to "FULL-COLD" mark on dipstick.
2) Start and operate engine at fast idle. Recheck reservoir
level. Add to "FULL-COLD" mark on dipstick. Turn wheels from side to
side without contacting stops. Maintain fluid level just above pump
body.
3) When air is removed, return wheels to straight-ahead
position. Operate engine 2-3 minutes. Stop engine. Road test vehicle.
Recheck fluid level. Level should be at "FULL-HOT" position after
system has stabilized. Add fluid (if necessary). DO NOT overfill.
BELT TENSION (Tension in Lbs. Using Boroughs Tension Gauge)









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Application New Belt Used Belt
Jeep ................ ( 1) 125-155 ............... 90-115
( 1) - Cherokee, Comanche and Wagoneer is 120-140 lbs.









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TROUBLE SHOOTING
Refer to TROUBLE SHOOTING - BASIC PROCEDURES article in the
GENERAL TROUBLE SHOOTING section.
TESTING