lock JEEP CHEROKEE 1988 Service Repair Manual
[x] Cancel search | Manufacturer: JEEP, Model Year: 1988, Model line: CHEROKEE, Model: JEEP CHEROKEE 1988Pages: 1378, PDF Size: 19.9 MB
Page 4 of 1378
Removal
1) Remove PCV valve hose at valve cover. Remove valve cover
bolts. Using a razor knife, cut RTV sealant along valve cover. Pry
upward on valve cover in areas marked "PRY HERE" near bolt hole areas.
2) Remove valve cover. Alternately loosen each rocker arm
bolt one turn at a time. Remove rocker arm assemblies and push rods.
Mark components for reassembly. Components must be installed in
original location.
Installation
Reverse removal procedures. Install rocker arm components in
original location. Tighten bolts to specification. Apply RTV sealant
on valve cover prior to installation.
VALVE SPRINGS
Valve springs can be removed without removing cylinder head.
Valve Spring Installed Height
Information not available from manufacturer.
HYDRAULIC VALVE LIFTERS
Removal
Remove rocker arms and push rods. See ROCKER ARMS & BRIDGE.
Using Lifter Remover/Installer (J-21884), remove lifter through push
rod openings of cylinder head. Mark lifter location for reassembly
reference. Replace lifters as an assembly if damaged. Internal
components cannot be interchanged.
Inspection
Inspect lifter and camshaft mating surfaces for wear. Check
cylinder block lifter bore diameter. Lifter bore diameter should be
within .9055-.9065" (22.999-23.025 mm). Replace parts as necessary.
Installation
Soak lifter assembly in engine oil supplement prior to
installation. Reverse removal procedures for installation. Install
lifter in original location.
ENGINE FRONT COVER
Removal
1) Disconnect negative battery cable. Remove drive belts, fan
and hub assembly. Remove pulley from vibration damper. Remove
vibration damper retaining bolt and washer.
2) Using Puller (J-21719-01), remove vibration damper and
key. Remove oil pan-to-front cover bolts. Remove cover-to-block
retaining bolts. Remove front cover.
3) Cut oil pan gasket even with face of cylinder block.
Remove gasket from oil pan. Pry crankshaft oil seal from cover.
Installation
1) Ensure all gasket surfaces are clean. Ensure oil slinger
is installed on crankshaft. Apply sealing compound on both sides of
front cover gasket. Install gasket on cylinder block. Replace front
section of oil pan seal with similar section fabricated from new seal.
2) Coat seal with RTV sealant and place in position. Apply
sealant to the joint area of oil pan and cylinder block. Place front
cover on cylinder block. Place Front Cover Seal Installer (J-22248) in\
front cover seal area.
3) Install all retaining bolts. Tighten bolts to
Page 5 of 1378
specification. Install front cover oil seal. See FRONT COVER OIL SEAL
Remove front cover seal installer.
4) Reverse removal procedures. Lubricate vibration damper
retaining bolt with oil prior to installation. Tighten bolts to
specification.
FRONT COVER OIL SEAL
Removal & Installation
1) Remove vibration damper. Using Seal Remover (J-9256),
remove seal from front cover. Position new seal on Front Cover Seal
Installer (J-22248) with lip facing outward.
2) Apply sealant to seal outer diameter. Lightly coat
crankshaft with oil. Place front cover seal installer on front of
crankshaft. Tap seal into front cover. Remove seal installer. Lightly
coat seal contact area of vibration damper with oil.
3) Install key in crankshaft (if removed). Install vibration\
damper. Lubricate vibration damper bolt with oil. Install retaining
bolt and washer. Tighten to specification.
CAMSHAFT & TIMING GEAR
Removal
1) Drain cooling system. Remove radiator. Remove engine front
cover. See ENGINE FRONT COVER. Remove distributor. Remove fuel pump
(if equipped with mechanical pump). Remove rocker arms and pushrods.
See ROCKER ARMS & BRIDGE under VALVES.
2) Remove valve lifters. Mark lifters for location. Remove
crankshaft oil slinger. Pull chain tensioner block toward tensioner
lever to compress spring. Hold block and move tensioner lever to lock
position. See Fig. 3.
3) Rotate crankshaft and align timing marks on crankshaft and
camshaft gears. Remove camshaft gear retaining bolt. Remove gears and
timing chain. Remove camshaft.
Fig. 3: Location of Chain Tensioner Lock
Courtesy of Chrysler Motors.
Inspection
Inspect camshaft for flaking, lobe wear or worn bearing
Page 6 of 1378
journals. Replace if not within specification. See ENGINE
SPECIFICATIONS tables.
Installation
1) Lubricate camshaft and install. Avoid damage to camshaft
bearings. Install timing gears and timing chain. Rotate crankshaft and
camshaft so timing marks are aligned. See Fig. 4.
2) Install camshaft gear retaining bolt. Tighten to
specification. Install crankshaft oil slinger. Position chain tension
tensioner lever to the unlock (down) position. Reverse removal
procedures to complete installation.
CAUTION: Ensure chain tensioner is released prior to front cover
installation.
Fig. 4: Aligning Timing Marks
CAMSHAFT BEARINGS
Removal & Installation
Replace camshaft bearings using camshaft bearing remover/
installer. Ensure oil holes are aligned after installation.
Page 7 of 1378
OIL PAN
See OIL PAN REMOVAL article.
PISTON & ROD ASSEMBLY
NOTE: Mark piston cylinder location for reassembly reference.
Install pistons in original cylinder location.
Removal
1) Remove cylinder head. See CYLINDER HEAD under MANIFOLDS &
CYLINDER HEAD. Remove oil pan. See OIL PAN REMOVAL article. Remove
ridge or deposits from cylinder bore.
2) Mark connecting rod and piston for cylinder ID. Remove
bearing cap. Remove piston and rod assembly.
CAUTION: Arrow on top of piston must point toward front of engine.
Oil squirt holes in connecting rod must face camshaft when
installed.
Installation
1) Ensure ring end gap and side clearance are within
specification. See ENGINE SPECIFICATIONS tables. Install rings on
piston. Position ring end gaps at specified areas. See Fig. 5.
Fig. 5: Positioning Piston Ring Gaps
Ring gaps may vary 20 degrees from positions illustrated.
2) Lubricate piston assembly and cylinder block. Install
piston assembly. Arrow on top of piston must face toward front of
Page 12 of 1378
1) Drain cooling system. Remove fan shroud and drive belts.
Remove fan assembly.
2) Disconnect heater hoses and lower radiator hose at water
pump. Remove water pump retaining bolts. Remove water pump.
Installation
Clean all gasket surfaces. 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 With 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 Without 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 system capacities and
other cooling system components, see ENGINE COOLING SYSTEMS
article.
ENGINE OILING
CRANKCASE CAPACITY
Crankcase capacity is 4 qts. (3.8 L) with oil filter change.
NORMAL OIL PRESSURE
Normal oil pressure should be 13 psi (.91 kg/cm) at 600 RPM
or 37-75 psi (2.6-5.3 kg/cm) at 1600 RPM.
OIL PRESSURE REGULATOR VALVE
Oil pressure regulator valve is located in oil pump body and
is nonadjustable.
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 runs along right
side of block and intersects 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. By-pass valves are located in oil filter mounting and oil
pump.
OIL PUMP
Removal
Remove oil pan. See OIL PAN REMOVAL article. Remove oil pump
Page 15 of 1378
Step 1 ........................................ 40 (54)
Step 2 ........................................ 70 (95)
Step 3 ....................................... 80 (109)
Oil Pump Retaining Bolt
Short .......................................... 10 (14)
Long ........................................... 17 (23)
Oxygen Sensor .................................... 35 (47)
Pulley-to-Vibration Damper Bolt .................. 20 (27)
Rocker Arm Bolt .................................. 19 (26)
Throttle Body-to-Intake Bolt ..................... 16 (22)
Torque Converter Drive
Plate-to-Crankshaft Bolt .................... (1) 40 (54)
Vibration Damper Bolt ....................... ( 2) 80 (109)
Water Pump Bolt .................................. 13 (18)
INCH Lbs. (N.m)
Front Cover-to-Block
Bolt ............................................ 60 (7)
Stud .......................................... 192 (22)
Oil Pan Bolt
1/4" X 20 ....................................... 84 (9)
5/16" X 18 .................................... 132 (15)
Oil Pump Cover Bolt ............................... 70 (8)
Valve Cover Bolt .................................. 55 (5)
( 1) - Tighten to specification and an additional 60 degrees.
( 2) - With bolt cleaned and threads lubricated with oil.
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ENGINE SPECIFICATIONS
GENERAL ENGINE SPECIFICATIONS
GENERAL ENGINE SPECIFICATIONS TABLE \
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Application In. (mm)
Displacement
Cu. In. ............................................ 150
Liters ............................................. 2.5
Fuel System .......................................... TBI
HP @ RPM ...................................... 117 @ 5000
Torque Ft. Lbs. @ RPM ......................... 135 @ 3500
Compression Ratio .................................. 9.2:1
Bore ......................................... 3.88 (98.5)
Stroke ....................................... 3.19 (81.0)
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VALVE SPECIFICATIONS
VALVE SPECIFICATIONS TABLE \
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Application In. (mm)
Intake ( 1)
Head Diameter ................ 1.905-1.915 (48.38-48.60)
Face Angle ......................................... 44
Seat Angle ..................................... 44 30'
Seat Width ................... ( 2) .040-.060 (1.02-1.52)
Stem Diameter .................... .311-.312 (7.89-7.98)
Stem Clearance ..................... .001-.003 (.02-.08)
Valve Lift ................................ .424 (10.76)
Page 59 of 1378
VALVE SPRING
Valve springs can be removed without removing cylinder head.
Valve Spring Installed
For 4.0L the Valve Spring Installed Height Specification is
1.625 inches or 41.29 mm. For the 4.2L the information is not
available from manufacturer.
HYDRAULIC VALVE LIFTER
Removal
Remove cylinder head. See CYLINDER HEAD. Using Lifter
Remover/Installer (J-21884), remove lifter. Mark lifter location for
reassembly reference. Replace lifters as an assembly if damaged.
Internal components cannot be interchanged.
Inspection
Inspect lifter and camshaft mating surfaces for wear. Check
cylinder block lifter bore diameter. Lifter bore diameter should be
within .9055-.9065" (22.999-23.025 mm). Replace parts as necessary.
Installation
Soak lifter assembly in engine oil prior to installation.
Reverse removal procedure for installation. Install lifter in original
location.
ENGINE FRONT COVER
Removal
1) Disconnect negative battery cable. Remove drive belts, fan
and hub assembly. Remove pulley from vibration damper. Remove
vibration damper retaining bolt and washer.
2) Using Puller (J-21719-01), remove vibration damper and
key. Remove alternator and A/C compressor bracket (if equipped).
Remove oil pan-to-front cover bolts. Remove cover-to-block retaining
bolts. Remove front cover.
3) Cut oil pan gasket tabs even with face of cylinder block.
Remove tabs. Remove gasket from oil pan. Pry crankshaft oil seal from
cover.
Installation
1) Ensure all gasket surfaces are clean. Ensure oil slinger
is installed on crankshaft. Apply sealing compound on both sides of
front cover gasket. Install gasket on cylinder block. Replace front
section of oil pan seal with similar section fabricated from new seal.
2) Coat seal with RTV sealant and place in position. Apply
sealant to the joint area of oil pan and cylinder block. Apply engine
oil on seal-to-oil pan contact areas.
3) Place front cover on cylinder block. Place Front Cover
Seal Installer (J-22248) in front cover seal area. Install all
retaining bolts. Tighten bolts to specification.
4) Install front cover oil seal. See FRONT COVER OIL SEAL in
this article. Remove front cover seal installer. Reverse removal
procedure for remaining components. Lubricate vibration damper
retaining bolt with oil prior to installation. Tighten bolts to
specification.
FRONT COVER OIL SEAL
1) Remove vibration damper. Pry seal from front cover. Use
Page 62 of 1378
Fig. 5: Positioning Piston Ring Gaps
Courtesy of Chrysler Motors
2) Lubricate piston assembly and cylinder block. Install
piston assembly. Arrows on top of piston must face toward front of
engine and connecting rod oil squirt hole should face camshaft side of
Page 66 of 1378
Crankshaft End Play
1) Using dial indicator, check crankshaft end play. Inspect
crankshaft thrust surfaces or thrust bearing for wear if not within
specification. See ENGINE SPECIFICATIONS table.
2) Replace thrust bearing if required. When replacing thrust
bearing, pry crankshaft forward then reward prior to tightening main
bearing cap to specification. Recheck end play. Replace crankshaft if
not within specification.
REAR MAIN OIL SEAL
Removal
1) Remove oil pan. See OIL PAN REMOVAL in this section.
Remove rear main bearing cap. Note direction of seal lip installation.
Remove seal from bearing cap. Loosen all remaining main bearing cap
bolts.
2) Using a brass drift, tap upper seal around crankshaft
until seal protrudes enough to permit removal with pliers. Remove
seal.
Installation
1) Clean crankshaft seal surface. Coat seal-to-block contact
areas with liquid soap. Lightly coat all seal lips with engine oil.
See Fig. 7 . Install upper seal into block with lip facing toward front
of engine.
2) Apply Silicone sealer on both sides of lower seal tabs.
Ensure no sealer is applied on seal lip. Apply liquid soap on seal-to-
cap contact surfaces.
3) Install lower seal into bearing cap with lip facing toward
front of engine. Ensure seal is firmly seated in bearing cap. Apply
Silicone sealer to chamfered edges of bearing cap. See Fig. 7.
CAUTION: DO NOT apply Silicone sealer on cap-to-block contact
surfaces. Sealer should only be applied to chamfered edges
only.
4) Install rear main bearing cap. Tighten main bearing cap
bolts to specification.
Fig. 7: Installing Rear Main Bearing Oil Seal
Courtesy of Chrysler Motors.
WATER PUMP
Page 73 of 1378
\003
4.0 L C EC S YSTE M
1988 J e ep C hero ke e
1988 COMPUTERIZED ENGINE Controls
ENGINE CONTROL SYSTEM
JEEP 4.0L MPFI 6-CYLINDER
Cherokee, Comanche & Wagoneer
DESCRIPTION
The 4.0L engine control system controls engine operation to
lower exhaust emissions while maintaining good fuel economy and
driveability. The system is designed to maintain a 14.7:1 air/fuel
ratio under all engine operating conditions. When the ideal air/fuel
ratio is maintained, the catalytic converter can control oxides of
nitrogen (NOx), hydrocarbon (HC), and carbon monoxide (CO) emissio\
ns.
The system consists of the following sub-systems: Fuel
Control, Data Sensors and Switches, Electronic Control Unit (ECU),
Diagnostics, Electronic Spark Advance, Idle Speed Control, Exhaust Gas
Recirculation, and Transmission Shift Light.
OPERATION
FUEL CONTROL
The fuel control system delivers fuel to the engine. Fuel
from the in-tank fuel pump flows to the fuel rail, injectors and
pressure regulator. The pressure regulator maintains fuel system
pressure at 31-39 psi (2.l-2.7 kg/cm
). Excess fuel is returned to the
tank by a fuel return line.
The fuel pump is energized through the fuel pump relay that
is located on the right inner fender panel in the engine compartment.
Battery voltage is provided through the ignition switch and is
energized when the ECU completes the ground path.
The fuel injectors are electrically operated solenoid valves.
The ECU determines injector pulse width ("on/off") time based upon
engine operating conditions and delivers the proper pulse width to
maintain an air/fuel ratio of 14.7:l.
The ECU varies the amount of voltage applied to the injectors
to compensate for battery voltage changes. Battery voltage information
is provided to the ECU through the wiring harness. No sensor or switch
is required.
DATA SENSORS & SWITCHES
Each sensor and/or switch furnishes electronic impulses to
the ECM. Based on these input signals, the ECM computes spark timing
and air/fuel mixture for proper engine operation.
Coolant Temperature Sensor (CTS)
The CTS is located on the left side of the block, just below
exhaust manifold. The sensor provides coolant temperature information
to the ECU. Engine coolant temperature is used by the ECU for the
following functions:
* Enrich air/fuel mixture for cold engine starts.
* Control idle speed during warm-up.
* Increase spark advance during cold engine operation.
* Prevent EGR flow during cold engine operation.