1988 JEEP CHEROKEE service

NOTE: Crankshaft journal diameters are indicated by a color coded
mark placed on the adjacent counterweight or cheek toward
the flanged (rear) end of crankshaft. Note color code to
determine proper bearing usage. Check oil clearance after
bearing installation.
Removal
1) Remove oil pan. See OIL PAN REMOVAL at end of ENGINE
section. See oil pump. See OIL PUMP under ENGINE OILING. Remove main
bearing cap.
2) Rotate crankshaft to position rod to be serviced at bottom
of stroke. Mark bearing cap and connecting rod. Remove bearing cap
with bearing. Push piston and rod assembly up to remove upper bearing.
Installation
1) Note color code on edge of bearings removed. Install
bearings. Using Plastigage method, check bearing clearances. Replace
bearings as necessary to obtain correct clearance. Bearings are
available in standard and undersize application.
2) If required, different sized upper and lower bearings may
be installed to obtain correct oil clearance. Tighten bolts to
specification. Check rod side play. Rotate crankshaft to ensure
freedom of movement. Reverse removal procedures for remaining
components. Tighten bolts to specification.
NOTE: Avoid combining bearing inserts in excess of .001" (.02 mm)
difference in size. Odd size inserts must be on bottom (rod
cap) side.
MAIN BEARINGS
Removal
1) Remove oil pan. See OIL PAN REMOVAL at end of ENGINE
section. Remove oil pump. See OIL PUMP under ENGINE OILING.
2) Ensure main bearing caps are marked for location. Rotate
crankshaft to remove bearings. Note color code on edge of bearing.
NOTE: Crankshaft journal diameters are indicated by a color coded
mark placed on the adjacent counterweight or cheek toward
the flanged (rear) end of crankshaft. Note color code to
determine proper bearing usage. Check oil clearance after
bearing installation.
Installation
1) Note color code on edge of bearings removed. Install
bearings. Ensure caps are installed in original location. Using
Plastigage method, check bearing clearances.
2) Replace bearings as necessary to obtain correct clearance.
Bearings are available in standard and undersize applications. If
required, different sized upper and lower bearings may be installed to
obtain correct oil clearance.
NOTE: If different sized bearings are used, the odd sized bearings
must all be uniform in location (upper or lower). DO NOT use
bearings with a thickness difference exceeding .001" (.02
mm).
3) Apply Loctite to corners of rear main bearing cap prior to
final installation. Tighten bolts to specification. Check crankshaft
end play. See CRANKSHAFT END PLAY. Rotate crankshaft to ensure freedom
of movement. Reverse removal procedures for remaining components.
Tighten bolts to specification.

ROD BEARING
NOTE: Crankshaft journal diameters are indicated by a color coded
mark placed on the adjacent counterweight or cheek toward
the flanged (rear) end of crankshaft. Note color code to
determine proper bearing usage. Check oil clearance after
bearing installation.
Removal
Remove oil pan. See OIL PAN REMOVAL at end of ENGINE section.
Rotate crankshaft to position rod to be serviced at bottom of stroke.
Mark bearing cap and connecting rod. Remove bearing cap with bearing.
Push piston and rod assembly up to remove upper bearing.
Installation
1) Note color code on edge of bearings removed. Install
bearings. Using Plastigage method, check bearing clearances. Replace
bearings as necessary to obtain correct clearance. Bearings are
available in standard and undersize application.
2) If required, different sized upper and lower bearings may
be installed to obtain correct oil clearance. Tighten bolts to
specification. Check rod side play. Rotate crankshaft to ensure
freedom of movement. Reverse removal procedure for remaining
components. Tighten bolts to specification.
NOTE: Avoid combining bearing inserts in excess of .001" (.02 mm)
difference in size.
MAIN BEARING
Removal
Remove oil pan. See OIL PAN REMOVAL at end of ENGINE section.
Ensure main bearing caps are marked for location. Remove bearing cap.
Rotate crankshaft to remove bearings. Note color code on edge of
bearing.
NOTE: Crankshaft main bearing journal diameters are indicated by a
color code. Color code is placed on the adjacent cheek
toward the flanged (rear) end of crankshaft for all except
the rear main. Rear main is color coded on the rear flange.
Note color code to determine proper bearing usage. Check oil
clearance after bearing installation.
Installation
1) Note color code on edge of bearings removed. Install
bearings. Ensure caps are installed in original location with arrow on
cap facing toward front of engine. Using Plastigage method, check
bearing clearances.
2) Replace bearings as necessary to obtain correct clearance.
Bearings are available in standard and undersize applications. If
required, different sized upper and lower bearings may be installed to
obtain correct oil clearance.
NOTE: If different sized bearings are used, odd sized bearings must
all be uniform in location (upper or lower). DO NOT use
bearings with a thickness difference exceeding
.001" (.02 mm).
3) Tighten bolts to specification. Check crankshaft end play.
See CRANKSHAFT END PLAY in this article. Rotate crankshaft to ensure
freedom of movement. Reverse removal procedure for remaining
components. Tighten bolts to specification.

Removal
Drain cooling system. Disconnect radiator and heater hoses
from pump. Remove drive belt(s). Remove fan shroud. Remove fan
assembly. Remove electric cooling fan (if equipped). Remove power
steering bracket from water pump. Remove water pump and gasket.
Installation
Ensure gasket surfaces are clean. Install water pump. Tighten
bolts to specification. Ensure pump turns freely. Reverse removal
procedures. Fill and purge air from cooling system.
NOTE: It may be necessary to remove heater hose to remove trapped
air if system cannot be purged using following procedures.
Cooling System Air Purge (Vehicles W/Coolant Recovery)
Fill system to proper level. Place heater control to "HEAT"
position and temperature control to "WARM" or "HIGH" position. Install
coolant caps. Operate engine to normal operating temperature. Shut off
engine and allow system to cool. Add coolant to recovery bottle.
Repeat procedure to obtain correct coolant level.
Cooling System Air Purge (Vehicles W/O Coolant Recovery)
Fill system to proper level. Place heater control to "HEAT"
position and temperature control to "WARM" or "HIGH" position. Operate
engine to normal operating temperature with radiator cap removed. Add
necessary coolant and install radiator cap.
NOTE: For further information on cooling systems, see appropriate
article in the ENGINE COOLING section.
LUBRICATION
CRANKCASE CAPACITY
Crankcase capacity for 4.0L is 5 1/2 qts. (5.2L) or 5 qts.
(4.7L) for 4.2L with oil filter change.
NORMAL OIL PRESSURE
Normal oil pressure should be 37-75 psi (2.6-5.3 kg/cm)
maximum above 1600 RPM. Minimum oil pressure should be 13 psi (.9
kg/cm
) at 600 RPM.
OIL PRESSURE REGULATOR VALVE
Oil pressure regulator valve is located in pump body. Valve
is nonadjustable and serviced as an assembly.
ENGINE OILING SYSTEM
Engine lubrication is provided by the distributor driven
gear-type oil pump. Oil is supplied through the full-flow oil filter
and into an internal oil passage. Internal passage provides oil to the
lifter bores. Oil is then routed to camshaft and crankshaft bearings.
Oil is supplied to rocker arms from the hydraulic lifters and through
the push rods.
OIL PUMP
Removal
Remove oil pan. See OIL PAN REMOVAL in this section. Remove

RVB Rear Vacuum Break 

RWAL Rear Wheel Anti-Lock Brake 

RWD Rear Wheel Drive 

Recirc. Recirculate or Recirculation 

Reg. Regulator 

Rly. Relay 











\








\









\









\









\









\









\





\f

"S" ABBREVIATION TABLE
"S" ABBREVIATION TABLE







\









\








\









\









\









\









\






 
ABBREVIATION DEFINITION 










\








\b
\









\









\









\









\









\






SAW Spark Angle Word 

SBC Single Bed Converter 

SBEC Single Board Engine Controller 

SC Super Charged 

SCC Spark Control Computer 

SCS Air Suction Control Solenoid 

SDM Supplemental Restraint System Diagnostic Module 

SDU SRS Diagnostic Unit 

SEN Sensor 

SES Service Engine Soon 

SFI Sequential (Port) Fuel Injection 

SIG RTN Signal Return circuit 

SIL Shift Indicator Light 

SIR Supplemental Inflatable Restraint 

SMEC Single Module Engine Controller 

SOHC Single Overhead Cam 

SOL or Sol. Solenoid 

SPFI Sequential Port Fuel Injection 

SPK Spark Control 

SPOUT Spark Output Signal 

SRS Supplemental Restraint System (Air Bag) 

SS 3/4-4/3 Shift Solenoid circuit 

SSI Solid State Ignition 

STAR Self-Test Automatic Readout 

STI Self Test Input circuit 

STO Self-Test Output 

SUB-O2 Sub Oxygen Sensor 

Sen. or Sens. Sensor 

Sol. Solenoid 

Sprchg. Supercharger 

Strg. Steering 

Susp. Suspension 

Sw. Switch 

Sys. System 











\








\









\









\









\









\









\





\f

"T" ABBREVIATION TABLE
"T" ABBREVIATION TABLE







\









\








\









\









\









\









\








ABBREVIATION DEFINITION 










\








\b
\









\









\









\









\









\






T.V. Throttle Valve 

TAB Thermactor Air By-Pass 

TAC Thermostatic Air Cleaner 

TAD Thermactor Air Diverter 

TAN Tan 

TBI Throttle Body Injection 

TCC Torque Converter Clutch 

TCCS Toyota Computer Control System 

TDC Top Dead Center 

TDCL Total Diagnostic Communication Link 

TFI Thick Film Ignition system 

TGS Top Gear Switch (cancels SIL in top gear) 

THERMAC Thermostatic Air Cleaner 

THS Transmission Hydraulic Switch 

TP/TPS Throttle Position Sensor 

TPI Tuned Port Injection 

TPS Throttle Position Sensor/Switch 

TS Temperature Sensor 

TSB Technical Service Bulletin 

TTS Transmission Temperature Switch 

TV Thermovalve 

TWC Three-Way Catalyst 

Temp. Temperature 

Trans. Transaxle/Transmission 











\








\









\









\









\









\









\





\f

"V" ABBREVIATION TABLE
"V" ABBREVIATION TABLE







\









\








\









\









\









\









\






 
ABBREVIATION DEFINITION 










\








\b
\









\









\









\









\









\






V Valve 

VAF Vane Air Flow sensor or circuit 

VAPS Variable Assist Power Steering 

VAT Vane Air Temperature 

VATS Vehicle Anti-Theft System 

VBATT Vehicle Battery Voltage 

VCC Viscous Converter Clutch 

VIN Vehicle Identification Number 

VIO Violet 

VLR Volt Loop Reserve 

VM Vacuum Modulator 

VM Vane Meter 

VOM Volt-Ohmmeter (Analog) 

VPWR Vehicle Power supply voltage (10-14 volts) 

VREF Voltage Reference (ECA supplied reference voltage 

VRV Vacuum Regulator Valve 

VSC Vehicle Speed Control sensor or signal 

VSS Vehicle Speed Sensor or signal 

VSV Vacuum Switching Valve 

Vac. Vacuum 

Volt. Voltage 











\








\









\









\









\









\









\





\f

"W" ABBREVIATION TABLE
"W" ABBREVIATION TABLE







\









\








\









\









\









\









\








ABBREVIATION DEFINITION 










\








\b
\









\









\









\









\









\






W/ With 

W/O Without 

WAC WOT A/C Cut-off switch or circuit 

WAC Wide Open Throttle A/C Switch 

WHT White 

WOT Wide Open Throttle 

YEL Yellow 

\003
A/C C O M PR ESSO R O IL C HEC KIN G

1988 J e ep C hero ke e
A/C General Servicing
COMPRESSOR OIL CHECK
* 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.
ISOLATING COMPRESSOR - GRAND WAGONEER ONLY
1) Connect service gauge set to the compressor service valves
and open compressor valves slightly (turn clockwise). Start engine and\
operate air conditioning. Slowly turn compressor suction valve
clockwise toward closed (front-seated) position.
2) When suction pressure is reduced to zero or less, turn off
engine and compressor and quickly turn suction valve stem in to full
front-seated position. Suction pressure should be slightly above zero.
Turn discharge valve into front-seated position.
3) To check oil lever, slowly open crankcase plug to relieve
any remaining pressure. After oil level is correct, cap service gauge
parts on both valves. Back-seat suction service valve to allow
refrigerant to enter compressor. Open discharge valve halfway.
4) Loosen discharge service valve cap, allowing refrigerant
pressure to force air out of compressor. Back-seat service valve and
tighten cap. Compressor is now ready for operation.
REFRIGERANT OIL
Only new, pure, moisture-free refrigerant oil should be used
in the air conditioning system. This oil is highly refined and
dehydrated to a point where moisture content is less than 10 parts per
million. The oil container must be tightly closed at all times when
not in use, or moisture will be absorbed from the air and introduced
into the refrigeration system.
DISCHARGING SYSTEM
CAUTION: When discharging air conditioning system, use only approved
refrigerant recovery/recycling equipment. Make every attempt
to avoid discharging refrigerant into the atmosphere.
If compressor has stem-type service valves, it can be
isolated and removed without discharging entire system. Otherwise,
discharge system completely using approved refrigerant
recovery/recycling equipment before loosening any fittings.
DISCONNECTING LINES & FITTINGS
After system is discharged, carefully clean area around all
fittings to be opened. Always use 2 wrenches when tightening or
loosening fittings to avoid twisting or distorting lines. Cap or plug
all openings as soon as lines are removed. Do not remove caps until
immediately before connections are made. This will keep entry of air
and moisture to a minimum, reducing the chance of damage to
components.

PLACING SYSTEM IN OPERATION
After component service or replacement has been completed and
all connections have been made, evacuate system throughly with a
vacuum pump. Charge system with proper amount of refrigerant and
perform a leak test. Be sure to check all fittings that have been
opened. After system has been leak tested, make a system performance
check.
SANDEN SD508 5-CYLINDER OIL CHECKING
1) Discharge system using approved refrigerant
recovery/recycling equipment. Remove compressor belt and loosen
mounting bolts. Rotate compressor in brackets until filler plug is at
top. Clean area around filler plug and remove plug slowly. Rotate
front hub plate so notch in lobe is 110 degrees from the bottom. This
rotates ball end of top piston to align with oil fill port and allows
clearance for dipstick. See Fig. 1.
2) Insert compressor dipstick diagonally from right to left
until stop on dipstick contacts filler plug surface. Remove dipstick
and note oil fill level. Each mark on dipstick represents one ounce
of oil. Add oil if necessary to reach 3-4 ounce level.
Fig. 1: Sanden 5-Cylinder Oil Level Checking
YORK - 2-CYLINDER - PURGINE COMPRESSOR

1) Remove gauge set and place caps on service valve ports.
Back-seat the suction service valve to allow refrigerant to enter
compressor.
2) Loosen discharge port valve slightly. Loosen valve port
cap to allow refrigerant to force out air from compressor. Back-seat
the discharge valve and tighten the port cap. Compressor is ready for
service.
YORK - 2-CYLINDER COMPRESSOR OIL CHECKING
1) Operate system for 10 minutes, then stop and isolate
compressor. Loosen filler plug slowly to release any pressure in
crankcase.
2) Use dipstick to check oil level. See Fig. 2. Add oil as
necessary, then install plug with new "O" ring. Purge compressor of
air.
Fig. 2: York A/C Compressor Oil Level Dipstick (Check oil w/ shaft
keyway facing head)
Courtesy of Chrysler Motors.