1988 JEEP CHEROKEE run flat

\003
A/C S YSTE M G EN ER AL S ER VIC IN G

1988 J e ep C hero ke e
1988 AIR CONDITIONING & HEAT
A/C General Servicing
Diagnostic Procedures
Eagle & Jeep
* PLEASE READ THIS FIRST *
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
INTRODUCTION
This article is to be used for general service and diagnosis.
For specific repair or replacement procedures, use the appropriate
repair article in this section.
R-12 REFRIGERANT - SAFETY PRECAUTIONS
1) Always work in a well-ventilated, clean area. Refrigerant
(R-12) is heavier than oxygen, and will displace oxygen in a confined
area. Always wear eye protection when working around air conditioning
systems and R-12. The system's high pressure can cause severe injury
to eyes and skin if a hose were to burst. R-12 evaporates quickly
when exposed to atmosphere, freezing anything it contacts.
2) Use care when handling refrigerant containers. Do not
drop or strike containers. Do not expose refrigerant containers to
excessive heat. Containers must never be heated more than 125
F.
Never expose R-12 directly to open flame.
CAUTION: When R-12 is exposed to an open flame, drawn into a running
engine, or detected with a Halide (propane) leak tester,
poisonous phosgene gas is formed. Keep work areas
ventilated and keep vehicles with running engines away.
USING INDIVIDUAL R-12 CANS
Disposable refrigerant cans (referred to as one pound cans)
have a flat type seal or a screw type seal, and the proper can tap
must be used for each type. Be sure sealing gasket on can tap is in
good condition. A proper safety can tap will prevent refrigerant from
flowing back into open can, as the tap has a one-way flow control.
NOTE: Recent findings by the EPA indicate that R-11, R-12 and
R-113 are harmful to the Earths' protective Ozone layer.
Make every attempt possible, to avoid discharging R-11, R-12
or R-113 into the atmosphere.
USING MULTI-CAN DISPENSING VALVES
A multi-can dispensing valve allows the attachment of
several cans of refrigerant, and is a good substitute when a bulk
container is not available. Cans are installed onto each leg of the
multi-can dispensing valve in the same manner as the individual cans,
and each leg has its own can tap.

Disassembly
Remove dust boots. Push pistons, piston cups and expander
spring out of bore. Discard cups. Clean all parts with brake solvent.
Inspect cylinder bore and piston for pitting, wear or damage. Replace
as necessary. Light scoring or pitting may be removed by honing.
Reassembly
1) Lubricate cylinder bore and internal components with brake
fluid. Do not lubricate dust boots. Position replacement piston cups
on spring expanders. Install assembled parts in cylinder bore.
2) Ensure expanders are seated in piston cups. Cups are to be
installed with lips facing each other. Install pistons with flat sides
facing interior of bore. Install dust boots.
TORQUE SPECIFICATIONS
TORQUE SPECIFICATIONS TABLE








\









\









\









\









\









\






Application Ft. Lbs. (N.m)
Disc Brakes
Caliper Mounting Bolts ......................... 35 (47)
Bleeder Screw .................................. 12 (16)
Brake Line-to-Caliper .......................... 13 (18)
Drum Brakes
Wheel Cylinder Bolts ........................... 11 (15)
Bleeder Screw 1/4" ........................... 4-5 (5-7)
Bleeder Screw 3/8" ......................... 4-10 (5-14)
Brake Line ............................... 10-17 (14-23)
Backing Plate Bolt ....................... 30-40 (41-54)
Master Cylinder Retaining Nuts
Except Grand Wagoneer .......................... 20 (27)









\









\









\









\









\









\






BRAKE SYSTEM SPECIFICATIONS
DISC BRAKE SPECIFICATIONS
DISC BRAKE SPECIFICATIONS TABLE








\









\









\









\









\









\






Application In. (mm)
Cherokee, Comanche, Wagoneer & Wrangler
Disc Diameter ............................ 11.02 (279.9)
Lateral Runout ............................ 0.005 (0.13)
Parallelism ............................... 0.001 (0.03)
Original Thickness ......................... 0.88 (22.4)
Min. Refinish Thickness .................. 0.815 (20.70)
Discard Thickness ........................ 0.815 (20.70)
Grand Wagoneer
Disc Diameter ............................ 12.00 (304.8)
Lateral Runout ............................ 0.005 (0.13)
Parallelism ............................... 0.001 (0.03)
Original Thickness ................................. N/A
Min. Refinish Thickness .................. 1.215 (30.86)
Discard Thickness ........................ 1.215 (30.86)









\









\









\









\









\









\






DRUM BRAKE SYSTEM SPECIFICATIONS
DRUM BRAKE SPECIFICATIONS TABLE

with tip resting on the main bearing journal area. See Fig. 21.
Rotate crankshaft and note reading. Journal runout must not exceed
specification. Repeat procedure on all main bearing journals.
Crankshaft must be replaced if runout exceeds specification.
Fig. 21: Measuring Crankshaft Main Bearing Journal Runout - Typical
This Graphic For General Information Only
INSTALLATION
Install upper main bearing in cylinder block. Ensure lock
tab is properly located in cylinder block. Install bearings in main
bearing caps. Ensure all oil passages are aligned. Install rear seal
(if removed).
Ensure crankshaft journals are clean. Lubricate upper main
bearings with clean engine oil. Carefully install crankshaft. Check
each main bearing clearance using Plastigage method. See
MAIN & CONNECTING ROD BEARING CLEARANCE in this article.
Once clearance is checked, lubricate lower main bearing and
journals. Install main bearing caps in original location. Install rear
seal in rear main bearing cap (if removed). Some rear main bearing
caps require sealant to be applied in corners to prevent oil leakage.
Install and tighten all bolts except thrust bearing cap to
specification. Tighten thrust bearing cap bolts finger tight only.
Thrust bearing must be aligned. On most applications, crankshaft
must be moved rearward then forward. Procedure may vary with
manufacturer. Thrust bearing cap is then tighten to specification.
Ensure crankshaft rotates freely. Crankshaft end play should be
checked. See CRANKSHAFT END PLAY in this article.
CRANKSHAFT END PLAY
Dial Indicator Method
Crankshaft end play can be checked using dial indicator.
Mount dial indicator on rear of cylinder block. Position dial
indicator tip against rear of crankshaft. Ensure tip is resting
against flat surface.
Pry crankshaft rearward. Adjust dial indicator to zero.

\003
PR E-A LIG NM EN T C HEC KS

1988 J e ep C hero ke e
Wheel Alignment
PRE-ALIGNMENT INSPECTION PROCEDURES
PRE-ALIGNMENT CHECKS
Before making wheel alignment adjustment, perform the
following checks:
1) Tires should be equal in size and runout must not be
excessive. Tires and wheels should be in balance, and inflated to
manufacturer's specifications.
2) Wheel bearings must be properly adjusted. Steering linkage
and suspension must not have excessive looseness. Check for wear in
tie rod ends and ball joints.
3) Steering gear box must not have excessive play. Check and
adjust to manufacturer's specifications.
4) Vehicle must be at curb height with full fuel load and
spare tire in vehicle. No extra load should be on vehicle.
5) Vehicle must be level with floor and with suspension
settled. Jounce front and rear of vehicle several times and allow it
to settle to normal curb height.
6) If steering wheel is not centered with front wheels in
straight-ahead position, correct by shortening one tie rod adjusting
sleeve and lengthening opposite sleeve equal amounts.
7) Ensure wheel lug nuts are tightened to torque
specifications.

(1) - Require replacement of units where dents restrict shock
or strut piston rod movement. If dents don't restrict
movement, no service is suggested or required. Especially
critical on mono-tube shocks.
( 2) - This condition can lead to damage of the piston rod,
which, in turn, causes premature piston rod seal wear.
( 3) - Only required if replacing cartridge.
( 4) - CAUTION: If the strut cartridge has been replaced previously,
the oil on the strut housing may be filler oil. The
technician must identify the source of the oil.
( 5) - If noise is isolated to shock or strut, suggest
replacement.
( 6) - Although shocks or struts may have contributed to tire
cupping, an inspection is needed of the entire suspension
system. If the shock or strut is found to be contributing
to the tire cupping, require replacement.









\









\









\









\









\









\









\


SPINDLES
SPINDLE INSPECTION








\









\









\









\









\









\









\


Condition Code Procedure
Attaching hardware
broken ................. A ... Require replacement of broken
part.
Attaching hardware
loose .................. A ... Require repair or replacement
of loose part.
Attaching hardware
missing ................ C .. Require replacement of missing
part.
Attaching hardware
threads damaged ........ A ... Require repair or replacement
of part with damaged threads.
Attaching hardware
threads stripped
(threads missing) ...... A ..... Require replacement of part
with stripped threads.
Bent .................... B ............ Require replacement.
Broken .................. A ............ Require replacement.
Race seat area
undersized ............. B ............ Require replacement.
Scored .................. A .. Require repair or replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.









\









\









\









\









\









\









\


SPRINGS - COIL, LEAF AND TORSION BAR
When springs are replaced, it is suggested, but not required,
that both springs on an axle be replaced to maintain equal height from
side to side and to provide a balanced ride and proper handling.
When variable rate springs are installed in place of
conventional coil springs, they must be installed in axle sets to
ensure proper handling, uniform ride, and proper chassis height.
Erroneous height measurements may result from: improper tire
inflation, non-standard tire or wheel size, and heavy load in vehicle
or trunk.
SPRING (COIL, LEAF AND TORSION BAR) INSPECTION

Condition Code Procedure
Air pressure incorrect .. B .................. Require repair
Bead broken ............. A ............ Require replacement.
Bead leaking, caused
by tire ................ A .. Require repair or replacement.
Bead wire/cord exposed .. A ............ Require replacement.
Cord or belt material
exposed ................ A ............ Require replacement.
Cord ply separations .... A ............ Require replacement.
Directional/asymmetrical
tires mounted
incorrectly ............ B ....... Require remounting and/or
repositioning.
Irregular tread wear,
affecting performance .. 2 ........ (1) Suggest replacement.
Load ratings less
than OEM
specifications ......... B ............ Require replacement.
Mixed tread types (all
season, performance, mud
and snow) on same axle . A ............ Require replacement.
Number of punctures
exceeds manufacturer's
limit .................. B ............ Require replacement.
Out of balance .......... B . Require rebalance of tire/wheel
assembly.
Ply separation .......... A ............ Require replacement.
Pull or lead, caused
by tire ................ A .. Require repair or replacement.
Radial and bias or
bias-belted ply tires
on same axle ........... B .. Require repair or replacement.
Radials are on the front
and not on the rear .... B ........... ( 2) Require repair or
replacement.
Run flat damage ......... A ............ Require replacement.
Shoulder cut ............ A ............ Require replacement.
Shoulder puncture ....... A ............ Require replacement.
Shoulder with plug ...... A ............ Require replacement.
Sidewall bulge .......... A ............ Require replacement.
Sidewall cut ............ A ............ Require replacement.
Sidewall indentation .... .. ......... No service required or
suggested.
Sidewall puncture ....... A ............ Require replacement.
Sidewall with plug ...... A ............ Require replacement.
Speed rating
designations
different
on same axle ........... 2 .. Suggest repair or replacement.
Tire and wheel assembly
has excessive run-out .. B ........... ( 3) Require repair or
replacement of appropriate
part.
Tires with more than
1/4" diameter difference
on a four-wheel drive
vehicle ................ B ............ Require replacement.
Tread area puncture larger
in diameter than
manufacturer's
specifications ......... B ............ Require replacement.
Tread missing pieces

(1) - Require replacement of units where dents restrict shock
or strut piston rod movement. If dents don't restrict
movement, no service is suggested or required. Especially
critical on mono-tube shocks.
( 2) - This condition can lead to damage of the piston rod,
which, in turn, causes premature piston rod seal wear.
( 3) - Only required if replacing cartridge.
( 4) - CAUTION: If the strut cartridge has been replaced previously,
the oil on the strut housing may be filler oil. The
technician must identify the source of the oil.
( 5) - If noise is isolated to shock or strut, suggest
replacement.
( 6) - Although shocks or struts may have contributed to tire
cupping, an inspection is needed of the entire suspension
system. If the shock or strut is found to be contributing
to the tire cupping, require replacement.









\









\









\









\









\









\









\


SPINDLES
SPINDLE INSPECTION








\









\









\









\









\









\









\


Condition Code Procedure
Attaching hardware
broken ................. A ... Require replacement of broken
part.
Attaching hardware
loose .................. A ... Require repair or replacement
of loose part.
Attaching hardware
missing ................ C .. Require replacement of missing
part.
Attaching hardware
threads damaged ........ A ... Require repair or replacement
of part with damaged threads.
Attaching hardware
threads stripped
(threads missing) ...... A ..... Require replacement of part
with stripped threads.
Bent .................... B ............ Require replacement.
Broken .................. A ............ Require replacement.
Race seat area
undersized ............. B ............ Require replacement.
Scored .................. A .. Require repair or replacement.
Threads damaged ......... A .. Require repair or replacement.
Threads stripped (threads
missing) ............... A ............ Require replacement.









\









\









\









\









\









\









\


SPRINGS - COIL, LEAF AND TORSION BAR
When springs are replaced, it is suggested, but not required,
that both springs on an axle be replaced to maintain equal height from
side to side and to provide a balanced ride and proper handling.
When variable rate springs are installed in place of
conventional coil springs, they must be installed in axle sets to
ensure proper handling, uniform ride, and proper chassis height.
Erroneous height measurements may result from: improper tire
inflation, non-standard tire or wheel size, and heavy load in vehicle
or trunk.
SPRING (COIL, LEAF AND TORSION BAR) INSPECTION

Condition Code Procedure
Air pressure incorrect .. B .................. Require repair
Bead broken ............. A ............ Require replacement.
Bead leaking, caused
by tire ................ A .. Require repair or replacement.
Bead wire/cord exposed .. A ............ Require replacement.
Cord or belt material
exposed ................ A ............ Require replacement.
Cord ply separations .... A ............ Require replacement.
Directional/asymmetrical
tires mounted
incorrectly ............ B ....... Require remounting and/or
repositioning.
Irregular tread wear,
affecting performance .. 2 ........ (1) Suggest replacement.
Load ratings less
than OEM
specifications ......... B ............ Require replacement.
Mixed tread types (all
season, performance, mud
and snow) on same axle . A ............ Require replacement.
Number of punctures
exceeds manufacturer's
limit .................. B ............ Require replacement.
Out of balance .......... B . Require rebalance of tire/wheel
assembly.
Ply separation .......... A ............ Require replacement.
Pull or lead, caused
by tire ................ A .. Require repair or replacement.
Radial and bias or
bias-belted ply tires
on same axle ........... B .. Require repair or replacement.
Radials are on the front
and not on the rear .... B ........... ( 2) Require repair or
replacement.
Run flat damage ......... A ............ Require replacement.
Shoulder cut ............ A ............ Require replacement.
Shoulder puncture ....... A ............ Require replacement.
Shoulder with plug ...... A ............ Require replacement.
Sidewall bulge .......... A ............ Require replacement.
Sidewall cut ............ A ............ Require replacement.
Sidewall indentation .... .. ......... No service required or
suggested.
Sidewall puncture ....... A ............ Require replacement.
Sidewall with plug ...... A ............ Require replacement.
Speed rating
designations
different
on same axle ........... 2 .. Suggest repair or replacement.
Tire and wheel assembly
has excessive run-out .. B ........... ( 3) Require repair or
replacement of appropriate
part.
Tires with more than
1/4" diameter difference
on a four-wheel drive
vehicle ................ B ............ Require replacement.
Tread area puncture larger
in diameter than
manufacturer's
specifications ......... B ............ Require replacement.
Tread missing pieces