engine JEEP YJ 1995 Service And Owners Manual

SERPENTINE DRIVE BELT DIAGNOSIS
JENGINE ACCESSORY DRIVE BELTS 7 - 39

BELT SERVICEÐEXCEPT RIGHT HAND DRIVE
The following procedures are for models equipped
with conventional left hand drive. Also refer to Belt
ServiceÐWith Right Hand Drive.
REPLACEMENT/ADJUSTMENT
Belt tension is adjusted at the power steering
pump (or idler pulley if not equipped with power
steering). To adjust belt tension or to replace belt:
SERPENTINE DRIVE BELT DIAGNOSIS (CONT.)
Fig. 2 YJ Models with 4.0L Engine, and XJ Models
with 2.5L EngineÐWith A/CFig. 3 YJ Models With 2.5L or 4.0L Engine, and XJ
Models with 2.5L EngineÐWithout A/C
7 - 40 ENGINE ACCESSORY DRIVE BELTSJ

(1) Loosen two rear power steering pump mounting
bolts A (Fig. 8).
(2) Loosen upper pump pivot bolt B and lower lock
nut C (Fig. 9).
(3) Loosen pump adjusting bolt D (Fig. 8).
(4) If belt is to be adjusted, refer to Drive Belt Ten-
sion specifications at the end of this group for correct
tension and proceed to step 7.
If belt is to be replaced, remove belt.
(5) Check condition of all pulleys.
CAUTION: When installing the serpentine accessory
drive belt, the belt MUST be routed correctly. If not,
the engine may overheat due to the water pump ro-
tating in the wrong direction. Refer to (Figs. 2, 3, 4
or 5) for correct belt routing.
(6) Install new belt. Refer to the end of this group
for Drive Belt Tension specifications.
(7) Tighten pump adjusting bolt D (Fig. 8) to at-
tain proper belt tension.(8) Tighten rear pump mounting bolts, pivot bolt
and lock nut to 27 Nzm (20 ft. lbs.) torque.
Fig. 4 XJ Models with 4.0L EngineÐWithout
A/CÐExcept RHD
Fig. 5 XJ Models With 4.0L EngineÐWith A/CÐ
Except RHD
Fig. 6 XJ Models With 4.0L EngineÐWith A/CÐWith
RHD
Fig. 7 Automatic Belt TensionerÐ4.0L Engine With
RHD
JENGINE ACCESSORY DRIVE BELTS 7 - 41

(9) After power steering pump has been tightened
into position, recheck belt tension. Adjust if neces-
sary.
BELT SERVICEÐXJ MODELS WITH RIGHT HAND
DRIVE
The automatic belt tensioner is used only on
XJ models equipped with a 4.0L 6-cylinder en-
gine with right hand drive steering system.
REMOVAL
(1) Attach a socket/wrench to the mounting bolt of
the automatic tensioner pulley (Fig. 7).
(2) Rotate the tensioner assembly clockwise (as
viewed from front) until tension has been relieved
from belt.
(3) Remove belt from idler pulley (Fig. 7) first. Re-
move belt from vehicle.
(4) Check condition and alignment of all pulleys.
INSTALLATION
(1) Position the drive belt over all pulleysexcept
the idler pulley (Fig. 7).
CAUTION: When installing the serpentine accessory
drive belt, the belt must be routed correctly. If not,
the engine may overheat due to the water pump ro-
tating in the wrong direction. Refer to (Fig. 6) for
correct engine belt routing. The correct belt with
the correct length must be used
(2) Attach a socket/wrench to the pulley mounting
bolt of the automatic tensioner (Fig. 7).
(3) Rotate the socket/wrench clockwise (Fig. 7).
Place the belt over the idler pulley. Let tensioner ro-
tate back into place. Remove wrench. Be sure belt is
properly seated in the grooves of all pulleys.
AUTOMATIC BELT TENSIONERÐXJ MODELS WITH
RIGHT HAND DRIVE
The automatic belt tensioner is used only on
XJ models equipped with a 4.0L 6-cylinder en-
gine with right hand drive steering system.
The drive belt is equipped with a spring loaded au-
tomatic belt tensioner (Fig. 10). This belt tensioner
will be used with all belt configurations such as with
or without air conditioning.
REMOVAL
(1) Attach a socket/wrench to the mounting bolt of
the automatic tensioner pulley (Fig. 10).
(2) Rotate the tensioner assembly clockwise (as
viewed from front) until tension has been relieved
from belt.
(3) Remove belt from idler pulley (Fig. 10) first.
Remove belt from automatic tensioner.
(4) Remove tensioner mounting bolt (Fig. 10) from
tensioner bracket. Remove tensioner from vehicle.
Note alignment pin on the back of tensioner.
WARNING: BECAUSE OF HIGH SPRING PRES-
SURE, DO NOT ATTEMPT TO DISASSEMBLE AUTO-
MATIC TENSIONER. UNIT IS SERVICED AS AN
ASSEMBLY (EXCEPT FOR PULLEY).
(5) Remove tensioner pulley bolt. Remove pulley
from tensioner.
Fig. 8 P.S. Pump Rear Mounting BoltsÐTypical
Fig. 9 P.S. Pump Front Mounting Bolt/LocknutÐ
Typical
7 - 42 ENGINE ACCESSORY DRIVE BELTSJ

INSTALLATION
(1) Install pulley and pulley bolt to tensioner.
Tighten bolt to 90 Nzm (65 ft. lbs.) torque.
(2) Install tensioner assembly to mounting bracket.
An alignment pin is located on the back of tensioner.
Align this pin to the slotted hole in the mounting
bracket. Install mounting bolt and tighten to 41 Nzm
(30 ft. lbs.) torque. If automatic tensioner bracket-to-
generator mounting bracket bolts were removed,
tighten to 27 Nzm (20 ft. lbs.) torque.
(3) Position the drive belt over all pulleysexcept
the idler pulley (Fig. 10).
CAUTION: When installing the serpentine accessory
drive belt, the belt must be routed correctly. If not,
the engine may overheat due to the water pump ro-
tating in the wrong direction. Refer to (Fig. 6) for
correct engine belt routing. The correct belt with
the correct length must be used
(4) Attach a socket/wrench to the pulley mounting
bolt of the automatic tensioner (Fig. 10).
(5) Rotate the socket/wrench clockwise (Fig. 10).
Place the belt over the idler pulley. Let tensioner ro-
tate back into place. Remove wrench. Be sure belt is
properly seated on all pulleys.
Fig. 10 Automatic Belt TensionerÐ4.0L 6-Cylinder
Engine With RHD
JENGINE ACCESSORY DRIVE BELTS 7 - 43

ENGINE BLOCK HEATER
GENERAL INFORMATION
DESCRIPTION AND OPERATION
An optional engine block heater is available for all
models. The heater is equipped with a power cord.
The cord is attached to an engine compartment com-
ponent with tie-straps. The heater warms the engine
providing easier engine starting and faster warm-up
in low temperatures. The heater is mounted in a core
hole of the engine cylinder block (in place of a freeze
plug) with the heating element immersed in engine
coolant. Connect the power cord to a grounded 110-
120 volt AC electrical outlet with a grounded, three-
wire extension cord.
WARNING: DO NOT OPERATE ENGINE UNLESS
BLOCK HEATER CORD HAS BEEN DISCONNECTED
FROM POWER SOURCE AND SECURED IN PLACE.
BLOCK HEATER SPECIFICATIONS
²2.5L 4-Cylinder Engine: 115 Volts 400 Watts
²4.0L 6-Cylinder Engine: 120 Volts 600 Watts
REMOVAL
Refer to correct illustration (Figures 11, 12 or 13)
when servicing block heater.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES-
SURIZED. SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
(1) Drain coolant from radiator and engine cylinder
block.(2) Unplug power cord from block heater.
(3) Loosen screw in center of block heater (Figs. 11,
12 or 13).
(4) Remove block heater from cylinder block.
INSTALLATION
(1) Thoroughly clean the engine core hole and the
block heater seat.
(2) Insert block heater assembly into core hole
with element loop pointingUp.
(3) Seat block heater flush against block face.
Tighten mounting screw to 3.6 Nzm (32 in. lbs.)
torque.
(4) Fill cooling system with coolant. Pressurize sys-
tem and inspect for leaks.
(5) Plug power cord into block heater. Route cord
away from moving parts, linkages and exhaust sys-
tem components. Secure cord in place with tie-straps.
Fig. 13 Heater and CordÐYJ Models
Fig. 11 Heater and CordÐXJ with 2.5L 4-Cylinder
Engine
Fig. 12 Heater and CordÐXJ with 4.0L 6-Cylinder
Engine
7 - 44 ENGINE BLOCK HEATERJ

SPECIFICATIONS
GENERAL INFORMATION
The following specifications are published from the
latest information available at the time of publica-
tion.If anything differs between the specifica-
tions found on the Vehicle Emission Control
Information (VECI) label and the following
specifications, use specifications on VECI label.
The VECI label is located in the engine compart-
ment.
DRIVE BELT TENSION
Belt tension can be adjusted only on models
equipped with conventional left hand drive. Refer to
the following Belt TensionÐExcept RHD Models
chart for specifications.
It is not necessary to adjust belt tension on right
hand drive (RHD) vehicles if equipped with a 4.0L
6-cylinder engine. The engine is equipped with an
automatic belt tensioner. The tensioner maintains
correct belt tension at all times.Due to the use of
this belt tensioner, DO NOT attempt to use a
belt tension gauge on this engine.Refer to Auto-
matic Belt Tensioner for additional information.
COOLING SYSTEM CAPACITIES
BELT TENSIONÐEXCEPT RIGHT HAND DRIVE
(RHD) MODELS
JCOOLING SYSTEM SPECIFICATIONS 7 - 45

charged. However, even with these vents, hydrogen
gas can collect in or around the battery. If hydrogen
gas is exposed to flame or sparks, it can ignite.
If the electrolyte level is low, the battery could arc
internally and explode. If the battery is equipped
with removable cell caps, add distilled water when-
ever the electrolyte level is below the top of the
plates. If the battery cell caps cannot be removed, the
battery must be replaced when the electrolyte level is
low.
WARNING: DO NOT ATTEMPT TO ASSIST BOOST,
CHARGE, OR TEST BATTERY WHEN ELECTRO-
LYTE LEVEL IS BELOW THE TOP OF THE PLATES.
PERSONAL INJURY MAY OCCUR.
BATTERY RATINGS
Currently, there are 2 commonly accepted methods
for rating and comparing battery performance. These
ratings are called Cold Cranking Amperage (CCA),
and Reserve Capacity (RC). Be certain that a replace-
ment battery has CCA and RC ratings that equal or
exceed the original equipment specification for the
vehicle being serviced. See Battery Classifications
and Ratings charts in Specifications at the back of
this group.
COLD CRANKING AMPERAGE
The Cold Cranking Amperage (CCA) rating speci-
fies how much current (in amperes) the battery can
deliver for 30 seconds at -17.7ÉC (0ÉF). Terminal volt-
age must not fall below 7.2 volts during or after the
30 second discharge. The CCA required is generally
higher as engine displacement increases, depending
also upon the starter current draw requirements.
RESERVE CAPACITY
The Reserve Capacity (RC) rating specifies the
time (in minutes) it takes for battery terminal volt-
age to fall below 10.2 volts at a discharge rate of 25
amps. RC is determined with the battery fully-
charged at 26.7ÉC (80ÉF). This rating estimates how
long the battery might last after a charging system
failure, under minimum electrical load.
DIAGNOSIS
The battery must be completely charged and the
top, posts, and terminal clamps should be properly
cleaned before diagnostic procedures are performed.
Refer to Group 8B - Battery/Starter/Generator Ser-
vice for more information.
The condition of a battery is determined by two cri-
teria:
(1)State-Of-ChargeThis can be determined by
viewing the built-in test indicator, by checking spe-
cific gravity of the electrolyte (hydrometer test), or by
checking battery voltage (open circuit voltage test).(2)Cranking CapacityThis can be determined
by performing a battery load test, which measures
the ability of the battery to supply high-amperage
current.
If the battery has a built-in test indicator, use this
test first. If it has no test indicator, but has remov-
able cell caps, perform the hydrometer test first. If
cell caps are not removable, or a hydrometer is not
available, perform the open circuit voltage test first.
The battery must be charged before proceeding
with a load test if:
²the built-in test indicator has a black or dark color
visible
²the temperature corrected specific gravity is less
than 1.235
²the open circuit voltage is less than 12.4 volts.
A battery that will not accept a charge is faulty
and further testing is not required. A battery that is
fully-charged, but does not pass the load test is
faulty and must be replaced.
Completely discharged batteries may take
several hours to accept a charge. See Charging
Completely Discharged Battery.
A battery is fully-charged when:
²all cells are gassing freely during charging
²a green color is visible in the sight glass of the
built-in test indicator
²three corrected specific gravity tests, taken at
1-hour intervals, indicate no increase in specific grav-
ity
²open circuit voltage is 12.4 volts or greater.
ABNORMAL BATTERY DISCHARGING
Any of the following conditions can result in abnor-
mal battery discharging:
(1) Corroded battery posts and terminals.
(2) Loose or worn generator drive belt.
(3) Electrical loads that exceed the output of the
charging system, possibly due to equipment installed
after manufacture or repeated short trip use.
(4) Slow driving speeds (heavy traffic conditions) or
prolonged idling with high-amperage draw systems
in use.
(5) Faulty circuit or component causing excessive
ignition-off draw. See Ignition-Off Draw in this group
for diagnosis.
(6) Faulty charging system.
(7) Faulty or incorrect battery.
BUILT-IN TEST INDICATOR
A test indicator (hydrometer) built into the top of
the battery case, provides visual information for bat-
tery testing (Fig. 1). It is important when using the
test indicator that the battery be level and have a
clean sight glass to see correct indications. Additional
light may be required to view indicator.
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 3

STARTING SYSTEM
GENERAL INFORMATION
The starting system (Fig. 1) consists of:
²ignition switch
²starter relay
²park/neutral position switch (automatic transmis-
sion)
²wiring harness and connections
²battery
²starter with an integral solenoid.
Following is a general description of the major
starting system components. Refer to Group 8W -
Wiring Diagrams for complete circuit descriptions
and diagrams.
These components form 2 separate circuits. A high-
amperage feed circuit that feeds the starter up to
300+ amps, and a low-amperage control circuit that
operates on less than 20 amps.
Battery voltage is supplied through the low-amper-
age control circuit to the coil battery terminal of the
starter relay when the ignition switch is turned to
the START position.
If the vehicle is equipped with an automatic trans-
mission, the park/neutral position switch provides a
ground path to the starter relay coil ground terminal.
This switch provides ground only with the transmis-
sion in NEUTRAL or PARK. If the vehicle is
equipped with a manual transmission, the starter re-
lay coil ground terminal is always grounded.
With the starter relay coil now energized, the nor-
mally open relay contacts close. The relay contacts
connect the relay common feed terminal to the relay
normally open terminal. The closed relay contacts en-
ergize the starter solenoid coil windings.
The energized solenoid coils pull-in and hold-in the
solenoid plunger. The solenoid plunger pulls the shiftlever in the starter. This engages the starter overrun-
ning clutch and pinion gear with the flywheel/drive
plate ring gear.
As the solenoid plunger reaches the end of its
travel, the solenoid contact disc completes the high-
amperage starter feed circuit. Current now flows be-
tween the solenoid battery terminal and the starter
motor, energizing the starter.
Once the engine starts, the overrunning clutch pro-
tects the starter from damage by allowing the starter
pinion gear to spin faster than the pinion shaft.
When the driver releases the ignition switch to the
ON position the starter relay coil is de-energized.
This causes the relay contacts to open. When the re-
lay contacts open, the starter solenoid coil is de-ener-
gized.
When the solenoid coil is de-energized, the solenoid
plunger return spring returns the plunger to its re-
laxed position. This causes the contact disc to open
the starter feed circuit, and the shift lever to disen-
gage the overrunning clutch and pinion gear from the
ring gear.
The starter motor and solenoid are serviced only as
a complete assembly. If either component fails, the
entire assembly must be replaced.
DIAGNOSIS
Before removing any unit from the starting system
for repair, perform the following inspections:
INSPECTION
BATTERY INSPECTION
To determine condition of the battery, see Battery
in this group.
WIRING INSPECTION
Inspect wiring for damage. Inspect all connections
at:
²starter solenoid
²park/neutral position switch (automatic transmis-
sion)
²ignition switch
²starter relay
²battery (including all ground connections).
Clean, tighten and repair all connections as re-
quired.
SOLENOID, RELAY AND SWITCH INSPECTIONS
Inspect the solenoid, relay and ignition switch to
determine their condition. Also, if equipped with au-
tomatic transmission, inspect condition of the park/
neutral position switch. Testing information can be
found in the following pages.
Fig. 1 Starting System Components (Typical)
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 11

COLD CRANKING TEST
(1) Battery must be fully-charged and load tested
before proceeding. See Battery, in this group.
(2) Connect a suitable volt-ampere tester to the
battery terminals (Fig. 2). Refer to the operating in-
structions provided with the tester being used.
(3) Fully engage parking brake. Place manual
transmission in NEUTRAL, automatic transmission
in PARK.
(4) Verify that all lamps and accessories are OFF.
(5) Unplug Auto Shut-Down (ASD) relay from
Power Distribution Center (PDC) to prevent engine
from starting. Relay location is shown on underside
of PDC cover.
(6) Rotate and hold the ignition switch in the START
position. Note cranking voltage and amperage.
(a) If voltage reads above 9.6 volts and amperage
draw reads above specifications, see Feed Circuit Tests.
(b) If voltage reads 12.5 volts or greater and am-
perage reads below specifications, see Control Cir-
cuit Tests.
A cold engine will increase starter current
and reduce battery voltage.
FEED CIRCUIT TESTS
The starter feed circuit tests (voltage drop method)
will determine if there is excessive resistance in the
high-amperage circuit. When performing these tests,
it is important that the voltmeter be connected prop-
erly. Connect voltmeter leads to the terminals that
the cable connectors or clamps are attached to, not to
the cable connectors or clamps. For example: When
testing between the battery and solenoid, touch the
voltmeter leads to the battery post and the solenoid
threaded stud.
The following operation will require a voltmeter ac-
curate to 1/10 (0.10) volt. Before performing the tests,
be certain the following procedures are accomplished:
²unplug Auto Shut-Down (ASD) relay from Power
Distribution Center (PDC) to prevent engine from
starting²place transmission in NEUTRAL (manual trans-
mission) or PARK (automatic transmission)
²parking brake is applied
²
battery is fully-charged (see Battery, in this group).
(1) Connect positive lead of voltmeter to battery
negative post. Connect negative lead of voltmeter to
battery negative cable clamp (Fig. 3). Rotate and
hold ignition switch in the START position. Observe
voltmeter. If voltage is detected, correct poor contact
between cable clamp and post.
(2) Connect positive lead of voltmeter to battery
positive post. Connect negative lead of voltmeter to
battery positive cable clamp (Fig. 3). Rotate and hold
ignition switch in the START position. Observe volt-
meter. If voltage is detected, correct poor contact be-
tween cable clamp and post.
(3) Connect voltmeter to measure between the bat-
tery positive post and the starter solenoid battery
stud (Fig. 4). Rotate and hold ignition switch in the
START position. Observe voltmeter. If voltage reads
above 0.2 volt, correct poor contact at battery cable to
solenoid connection. Repeat test. If reading is still
above 0.2 volt, replace battery positive cable.
Fig. 2 Volt-Amps Tester Connections (Typical)
Fig. 3 Test Battery Connection Resistance
Fig. 4 Test Battery Positive Cable Resistance
(Typical)
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 13