Gear JEEP CHEROKEE 1988 Service Manual PDF

See GAUGES.
STARTERS
NOTE: To prevent misdiagnosis, care should be taken to
eliminate the possibilities of mechanical problems or
high resistance in power and/or ground circuits.
STARTER INSPECTION









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Condition Code Procedure
Amperage draw does not
meet OEM specifications . B .. Require repair or replacement.
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ........... ( 1) Require repair or
replacement of hardware.
Bracket bent, affecting
performance ............ A .. Require repair or replacement.
Bracket bent, not
affecting performance .. .. ........ No service suggested or
required.
Bracket broken, affecting
performance ............ A ............ Require replacement.
Bracket broken, not
affecting performance .. .. ........ No service suggested or
required.
Bracket corroded,
affecting performance .. A .. Require repair or replacement.
Bracket corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Bracket cracked, affecting
performance ............ A .. Require repair or replacement.
Bracket cracked, not
affecting performance .. 1 .. Suggest repair or replacement.
Bracket holes elongated,
affecting performance .. A .. Require repair or replacement.
Bracket holes elongated,
not affecting
performance) ........... .. ........ No service suggested or
required.
Bracket loose, affecting
performance ............ A .. Require repair or replacement.
Bracket loose, not
affecting performance .. 1 .. Suggest repair or replacement.
Bracket missing ......... C ............ Require replacement.
Drive gear damaged,
affecting performance .. A ........... ( 2) Require repair or
replacement.
Drive gear damaged, not
affecting performance .. 2 ........... ( 2) Suggest repair or
replacement.
Fails to disengage ...... A .. Require repair or replacement.
Housing broken, affecting
performance ............ 2 .. Require repair or replacement.
Housing broken, not

affecting performance .. .. ........ No service suggested or
required.
Housing cracked, affecting
performance ............ A ... Require repair or replacement.
Housing cracked, not
affecting performance .. 2 .. Suggest repair or replacement.
Inoperative ............. A ........... (3) Require repair or
replacement.
Noisy ................... 2 .. Suggest repair or replacement.
Shimmed incorrectly ..... B ................. Require repair.
Starter shaft bushing
missing ................ C ........ ( 4) Require replacement.
Starter shaft bushing
worn, affecting
performance ............ A ............ Require replacement.
Starter shaft bushing
worn, not affecting
performance ............ 1 ............ Suggest replacement.
Terminal broken ......... A .. Require repair or replacement.
Terminal burned, affecting
performance ............ A ........... ( 5) Require repair or
replacement.
Terminal burned, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal corroded,
affecting performance .. A .. Require repair or replacement.
Terminal corroded, not
affecting performance .. 2 .. Suggest repair or replacement.
Terminal loose, affecting
performance ............ B .. Require repair or replacement.
Terminal loose, not
affecting performance .. 1 .. Suggest repair or replacement.
( 1) - Inspect block or bell housing mounting surface.
( 2) - Further inspection required to determine cause. Require
inspection of ring gear.
( 3) - Inoperative includes intermittent operation.
( 4) - Bushing may be in bell housing.
( 5) - Determine cause and correct prior to repair or
replacement of part.









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SUB-WOOFER VOLUME CONTROLS
See
RECEIVERS, AMPLIFIERS, EQUALIZERS AND SUB-WOOFER VOLUME CONTROLS .
SWITCHES
SWITCH INSPECTION








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Condition Code Procedure
Attaching hardware
broken ................. A ... Require repair or replacement
of hardware.
Attaching hardware
missing ................ C .......... Require replacement of
hardware.
Attaching hardware not
functioning ............ A ... Require repair or replacement
of hardware.
Binding, affecting

EM IS SIO NS S TA N DAR DS

1988 J e ep C hero ke e
1988 EMISSION & TUNE-UP STANDARDS
MANUFACTURING STANDARDS
Federal and state governments have established air quality
standard during the past 20 years. Automobile manufacturers design
their vehicles to conform to standards where the vehicle will be sold
and operated. These standards cover carbon monoxide (CO), hydrocarbons\
(HC) and oxides of nitrogen (NOx).
Federal and California Standards which must be met by
manufacturers are specified in units easily measured in a testing
laboratory. Since 1970, these standards have been in "grams per mile".
This means no vehicle, whether 2-cylinder or V8, may emit more than a
set weight (in grams) of pollutants for each mile travelled. Since
large engines burn more fuel per mile than do small engines, they must
be "cleaner" per gallon burned if they are to meet these standards.
When manufacturers certify vehicle models prior to sale,
the vehicles are placed on a dynamometer and the exhaust gases are
collected in a bag. After the vehicle runs for a specified time, the
gases are analyzed and weighed. Engines and emission systems are
designed so the weight of emissions will be less than the specified
grams per mile standard.
Infra-red exhaust analyzers are commonly used in vehicle test
stations. The analyzer uses a test probe placed in the exhaust stream
to sample the exhaust gases, and measure the percentage of CO and the
parts per million of HC. These are not the same units used by the
manufacturer when the vehicle is certified. The NOx emissions cannot
be measured by an infra-red exhaust analyzer. Laboratory equipment
must be used to determine NOx emissions.
TUNE-UP STANDARDS
The technician must use the proper specifications when
adjusting the vehicle during a tune-up. The first few years of
emission-regulated vehicles were adjusted using an exhaust gas
analyzer which measured CO and HC.
In the past few years, manufacturers have produced much
cleaner running vehicles. The CO (percentage) and HC (ppm) have beco\
me
very low, especially when measured downstream of catalytic converter.
It has become difficult to measure the effect of fuel and ignition
adjustments.
One solution to this problem for vehicles using carburetors
requires the use of artificially-enriched propane adjustments. The
added propane increases or decreases engine RPM for evaluation of
carburetor rich/lean setting. This allows the technician to check
carburetor setting quickly and accurately.
As computer-controlled systems were developed, it became
possible for the vehicles to adjust the air/fuel ratio, ignition
timing and emission control device operation throughout the entire
driving range. These computer control systems use a variety of sensors
that provide the electronic control unit with information on vehicle
speed, altitude of vehicle operation and transmission gear position,
along with engine operating conditions.
Fuel delivery to achieve a lean air/fuel ratio is controlled
by the computer. The computer controls the on/off (duty cycle) time of\
the fuel injector(s) or carburetor mixture control solenoid to achieve\
leanest possible air/fuel ratio while maintaining good driveability.
Although most repair shops have exhaust gas analyzers,
computer-controlled vehicles normally do not have a CO and HC

CRANKSHAFT & MAIN BEARINGS
* PLEASE READ THIS FIRST *
NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
REMOVAL
Ensure all main bearing caps are marked for location on
cylinder block. Some main bearing caps have an arrow stamped on it
which must face front of engine. Remove main bearing cap bolts. Remove
main bearing caps. Carefully remove crankshaft. Use care not to bind
crankshaft in cylinder block during removal.
CLEANING & INSPECTION
Thoroughly clean crankshaft using solvent. Dry with
compressed air. Ensure all oil passages are clear and free of sludge,
rust, dirt, and metal chips.
Inspect crankshaft for scoring and nicks. Inspect crankshaft
for cracks using Magnaflux procedure. Inspect rear seal area for
grooving or damage. Inspect bolt hole threads for damage. If pilot
bearing or bushing is used, check pilot bearing or bushing fit in
crankshaft. Inspect crankshaft gear for damaged or cracked teeth.
Replace gear if damaged. Check that oil passage plugs are tight (if
equipped).
Using micrometer, measure all journals in 4 areas to
determine journal taper, out-of-round and undersize. See Fig. 20.
Some crankshafts can be reground to the next largest undersize,
depending on the amount of wear or damage. Crankshafts with rolled
fillet cannot be reground and must be replaced.
Fig. 20: Measuring Crankshaft Journal - Typical
This Graphic For General Information Only
Crankshaft journal runout should be checked. Install
crankshaft in "V" blocks or bench center. Position dial indicator

NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
CLEANING & INSPECTION
Clean camshaft with solvent. Ensure all oil passages are
clear. Inspect cam lobes and bearing journals for pitting, flaking or
scoring. Using micrometer, measure bearing journal O.D.
Support camshaft at each end with "V" blocks. Position dial
indicator with tip resting on center bearing journal. Rotate camshaft
and note reading. If reading exceeds specification, replace camshaft.
Check cam lobe lift by measuring base circle of camshaft
using micrometer. Measure again at 90 degrees to tip of cam lobe. Cam
lift can be determined by subtracting base circle diameter from tip of
cam lobe measurement.
Different lift dimensions are given for intake and exhaust
cam lobes. Reading must be within specifications. Replace camshaft if
cam lobes or bearing journals are not within specifications.
Inspect camshaft gear for chipped, eroded or damaged teeth.
Replace gear if damaged. On camshafts using thrust plate, measure
distance between thrust plate and camshaft shoulder. Replace thrust
plate if not within specification.
CAMSHAFT BEARINGS
Removal & Installation
Remove the camshaft rear plug. The camshaft bearing remover
is assembled with its shoulder resting on the bearing to be removed
according to manufacturer's instructions. Tighten puller nut until
bearing is removed. Remove remaining bearings, leaving front and rear
bearings until last. These bearings act as guide for camshaft bearing
remover.
To install new bearings, puller is rearranged to pull
bearings toward the center of block. Ensure all lubrication passages
of bearing are aligned with cylinder block. Coat new camshaft rear
plug with sealant. Install camshaft rear plug. Ensure plug is even
in cylinder block.
CAMSHAFT INSTALLATION
Lubricate bearing surfaces and cam lobes with ample amount of
Molykote or camshaft lubricant. Carefully install camshaft. Use care
not to damage bearing journals during installation. Install thrust
plate retaining bolts (if equipped). Tighten bolts to specification.
On overhead camshafts, install bearing caps in original location.
Tighten bolts to specification. Check end play.
CAMSHAFT END PLAY
Using dial indicator, check end play. Position dial indicator
on front of engine block. Position indicator tip against camshaft.
Push camshaft toward rear of engine and adjust indicator to zero.
Move camshaft forward and note reading. Camshaft end play
must be within specification. End play may be adjusted by relocating
gear, shimming thrust plate or replacing thrust plate depending on
manufacturer.
TIMING CHAINS & BELTS

* PLEASE READ THIS FIRST *
NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
TIMING CHAINS
Timing chains will stretch during operation. Limits are
placed upon amount of stretch before replacement is required. Timing
chain stretch will alter ignition timing and valve timing.
To check timing chain stretch, rotate crankshaft to eliminate
slack from one side of timing chain. Mark reference point on cylinder
block. Rotate crankshaft in opposite direction to eliminate slack from
remaining side of timing chain. Force other side of chain outward
and measure distance between reference point and timing chain. See
Fig. 23 . Replace timing chain and gears if not within specification.
Fig. 23: Measuring Timing Chain Stretch - Typical
This Graphic For General Information Only
Timing chains must be installed so that timing marks on
camshaft gear and crankshaft gear are aligned according to

manufacturer. See Fig. 24.
Fig. 24: Timing Gear Mark Alignment - Typical
This Graphic For General Information Only
TIMING BELTS
Cogged tooth belts are commonly used on overhead cam
engines. Inspect belt teeth for rounded corners or cracking. Replace
belt if cracked, damaged, missing teeth or oil soaked.
Used timing belt must be installed in original direction of
rotation. Inspect all sprocket teeth for wear. Replace all worn
sprockets. Sprockets are marked for timing purposes. Engine is
positioned so that crankshaft sprocket mark will be upward. Camshaft
sprocket is aligned with reference mark on cylinder head and timing
belt is installed. See Fig. 25.

Fig. 26: Timing Belt Tension Adjustment - Typical
This Graphic For General Information Only
TIMING GEARS

* PLEASE READ THIS FIRST *
NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
TIMING GEAR BACKLASH & RUNOUT
On engines where camshaft gear operates directly on
crankshaft gear, gear backlash and runout must be checked. To check
backlash, install dial indicator with tip resting on tooth of camshaft
gear. Rotate camshaft gear as far as possible. Adjust indicator to
zero. Rotate camshaft gear in opposite direction as far as possible
and note reading.
To determine timing gear runout, mount dial indicator with
tip resting on face edge of camshaft gear. Adjust indicator to zero.
Rotate camshaft gear 360 degrees and note reading. If backlash or
runout exceed specifications, replace camshaft and/or crankshaft
gear.
REAR MAIN OIL SEAL
* PLEASE READ THIS FIRST *
NOTE: Always refer to appropriate engine overhaul article in the
ENGINES section for complete overhaul procedures and
specifications for the vehicle being repaired.
INSTALLATION
One-Piece Type Seal
For one-piece type oil seal installation, coat block contact
surface of seal with sealer if seal is not factory coated. Ensure seal
surface is free of burrs. Lubricate seal lip with engine oil and press
seal into place using proper oil seal installer. See Fig. 27.
Fig. 27: Installing Typical One-Piece Oil Seal
This Graphic For General Information Only
Rope Type Seal
For rope type rear main oil seal installation, press seal

Fig. 31: Measuring Rotor Clearance - Typical
This Graphic For General Information Only
Install rotors in pump body. Position straightedge across
pump body. Using feeler gauge, measure clearance between rotors and
straightedge. Pump cover wear is measured using a straightedge and
feeler gauge. Replace pump if clearance exceeds specification.
GEAR TYPE
Oil pump gears must be marked for location prior to removal.
See Fig. 32 . Remove gears from pump body. Inspect gears for pitting
or damage. Inspect cover for grooving or wear.
Fig. 32: Typical Gear Type Oil Pump
This Graphic For General Information Only
Measure gear diameter and length. Measure gear housing cavity
depth and diameter. See Fig. 33. Replace components if worn or