1994 JEEP CHEROKEE service interval

LUBRICATION AND MAINTENANCE
CONTENTS
page page
CHASSIS AND BODY COMPONENTS....... 30
DRIVETRAIN........................... 22
ENGINE MAINTENANCE.................. 13GENERAL INFORMATION.................. 1
JUMP STARTING, HOISTING AND TOWING . . 7
MAINTENANCE SCHEDULES............... 5
GENERAL INFORMATION
INDEX
page page
Classification of Lubricants.................. 2
Components Requiring No Lubrication.......... 3
Fluid Capacities.......................... 4
Fuel Requirements........................ 2Introduction.............................. 1
Recommended Lubricant and Replacement Parts . 3
Routine Service........................... 2
INTRODUCTION
Jeeptlubrication and maintenance is divided into
required and recommended service tasks.
The recommendations and procedures listed in this
group are intended for JeeptDealer Service Personnel.
Because conditions vary, it is necessary to schedule
service tasks according to a time interval as well as a
distance interval.
It is the owner's responsibility to have vehicle ser-
viced. Owner is to pay for labor and necessary parts
that are not covered by the warranty.
Additional lubrication and maintenance informa-
tion is listed in the Owner's Manual, which is in-
cluded with the vehicle.
SEVERE DRIVING CONDITIONS
When a vehicle is subjected to a severe driving con-
dition, time between recommended maintenance
should be decreased.
Refer to Engine Maintenance for the engine oil and
filter maintenance interval when involved with a se-
vere driving condition.
A severe driving condition is defined as either:
²frequent short trip driving less than 24 km (15
miles);
²frequent driving in a dusty environment;
²trailer towing;
²extensive engine idling;
²sustained high-speed operation;
²desert operation;
²frequent starting and stopping;²cold-climate operation;
²off-road driving; or
²commercial service.
To service a Jeeptvehicle for a severe driving con-
dition, change all the lubricating fluids and lubricate:
²the body components,
²all the driveline coupling joints, and
²the steering linkage
more often than for a normal driving condition to
prevent excessive wear of the components.
DUSTY AREAS
Driving in an area with dust-filled air increases the
risk of particles entering the engine and crankcase.
With this type of severe driving condition, attention
should be given to the engine and crankcase compo-
nents.
OFF-ROAD (4WD) OPERATION
After completion of off-road (4WD) operation, the
underside of the vehicle should be thoroughly in-
spected. Examine threaded fasteners for looseness.
HARSH SURFACE ENVIRONMENTS
After vehicle operation in a harsh surface environ-
ment, the following components should be inspected
and cleaned as soon as possible:
²brake drums,
²brake linings,
²front wheel bearings (2WD vehicles only), and
²axle coupling joints.
This will prevent wear and/or unpredictable brake
action.
JLUBRICATION AND MAINTENANCE 0 - 1

ENGINE MAINTENANCE
INDEX
page page
Accessory Drive Belt...................... 20
Air-Conditioner Compressor/Hoses/Fittings...... 21
Battery................................ 18
Cooling System.......................... 16
Crankcase Ventilation System............... 17
Engine Air Cleaner Filter Element............ 16
Engine Break-In......................... 13
Engine Oil.............................. 13Engine Oil Change and Filter Replacement..... 15
Engine Oil Filter......................... 14
Engine Supports......................... 20
Exhaust System......................... 20
Fuel Usage StatementÐGas Engines......... 17
Ignition Cables, Distributor Cap and Rotor...... 18
Rubber and Plastic Ducts/Hoses/Tubing....... 19
Spark Plugs............................ 18
ENGINE BREAK-IN
After first starting a new engine, allow it to idle
and warm up for at least 15 seconds before shifting
the transmission into a drive gear.
Drive the vehicle at:
²varying speeds less than 80 km/h (50 mph) for the
first 160 km (100 miles), and
²speeds less than 88 km/h (55 mph) for the first 800
km (500 miles).
Avoid driving at full-throttle for extended periods
of time. Also, avoid fast acceleration and sudden
stops.
A special break-in engine oil is not required. The
original oil installed in a vehicle is a quality lubri-
cant. There is no requirement to have the oil
changed or the oil filter replaced until the first
scheduled maintenance interval.
The engine oil, coolant and all the other engine re-
lated fluid levels should be determined on a regular
basis.
ENGINE OIL
SPECIFICATIONS
API SERVICE GRADE
For maximum engine protection during all driving
conditions, install an engine oil that conforms to API
Service Grade. MOPAR Engine Oil conforms to all of
these API Service Grades.
SAE VISCOSITY
SAE designated multi-viscosity grade engine oil is
to protect engines. This type of engine oil can usually
be installed and remain in the engine until the next
scheduled oil change. Select the engine oil viscosity
according to the lowest ambient air temperature ex-
pected before the next scheduled oil change (Fig.1).
Low viscosity engine oil allows easier engine starting
during cold weather. SAE 5W-30 viscosity engine oil
is recommended when the ambient air temperatures
consistently decrease to below 10ÉF (-12ÉC).ENERGY CONSERVING OIL
In selecting the correct API grade and SAE grade,
anENERGY CONSERVINGtype engine oil is also
recommended.
CONTAINER IDENTIFICATION
Standard engine oil notations have been adopted
for selection of engine oil. The notations are located
on side of plastic bottles and on the top of engine oil
cans (Fig. 2).
²The top, outer field contains theAPI Service
Gradenotation for the engine oil.
Fig. 1 Temperature/Engine Oil Viscosity
Fig. 2 Engine Oil Container Standard Notations
JLUBRICATION AND MAINTENANCE 0 - 13

ENGINE OIL CHANGE AND FILTER REPLACEMENT
WARNING: CARE SHOULD BE TAKEN WHEN
CHANGING OIL. PROTECTIVE CLOTHING AND
GLOVES SHOULD BE WORN. EXPOSED SKIN
SHOULD BE WASHED WITH SOAP AND WATER TO
REMOVE ANY ENGINE OIL. DO NOT USE GASO-
LINE, THINNER, OR SOLVENTS TO REMOVE EN-
GINE OIL FROM SKIN.
REQUIRED MAINTENANCE
With normal driving conditions, engine oil and fil-
ter must be changed after each 12 000-km (7,500-
miles)/12-month interval. If the vehicle is involved
with a severe driving condition, after each 4 800-km
(3,000-miles)/3-month interval. A severe driving con-
dition includes:
²frequent short trip driving less than 24 km (15
miles);
²frequent driving in a dusty environment;
²trailer towing;
²extensive engine idling;
²sustained high-speed operation;
²desert operation;
²frequent starting and stopping;
²cold-climate operation;
²off-road driving; or
²commercial service.
OIL CHANGE AND FILTER REPLACEMENT
(1) Drain the engine oil from the crankcase. Wait
until after the engine has attained the normal oper-
ating temperature to ensure complete drainage of oil.
(2) Install the drain-hole plug with a replacement
gasket.
The oil filter should be replaced during every
engine oil change.
(3)
Rotate the oil filter counterclockwise to remove
it from the cylinder block oil filter boss (Figs. 6 and 7).
(4) Clean the cylinder block oil filter boss.
(5) Apply a light coat of engine oil to the rubber
seal on the replacement oil filter.
CAUTION: Do not use oil filter with metric threads.
The proper oil filter has SAE type 3/4 X 16 threads.
The use of an oil filter with metric threads can re-
sult in engine oil leaks and engine failure.
(6) Install andhand tightenthe oil filter 1/2 to
3/4 of-a-turn clockwise beyond the point where the
seal first contacts the cylinder block.
(7) Add engine oil in fill hole located on top of en-
gine cylinder head cover (Fig. 8).
(8) Observe the oil level on the dipstick. Add oil,
if necessary, to increase the level to the FULL mark.
Fig. 6 Oil Filter RemovalÐ2.5L Engine
Fig. 7 Oil FilterÐ4.0L Engine
Fig. 8 Adding Engine OilÐTypical
JLUBRICATION AND MAINTENANCE 0 - 15

CAUTION: Do not overfill the engine crankcase with
oil. This will cause oil aeration and result in a de-
crease in the engine oil pressure.
(9) Start the engine and observe the oil pressure
gauge or warning lamp. If the pressure does not in-
crease or the warning lamp does not go out, stop the
engine and determine the cause of the problem.
USED ENGINE OIL DISPOSAL
Care should be exercised when disposing used en-
gine oil after it has been drained from a vehicle en-
gine. Refer to the WARNING listed above.
COOLING SYSTEM
WARNING: USE EXTREME CAUTION WHEN RE-
MOVING THE RADIATOR CAP IF THE ENGINE IS
OPERATING. DO NOT PUT YOUR HANDS NEAR
THE DRIVE BELT(S), PULLEYS OR FAN BLADE. DO
NOT STAND IN A DIRECT LINE WITH THE FAN
BLADE.
RECOMMENDED MAINTENANCE
The engine coolant level should be determined at
least once a month and more often during periods of
hot weather. Add coolant as necessary.
COOLANT LEVEL
With the engine at normal operating temperature,
observe the coolant level in thecoolant recovery bot-
tle. The coolant level must be at least above the ADD
mark and preferably at the FULL mark. Add coolant
to the coolant recovery bottleonly, if necessary.
REQUIRED MAINTENANCE
Check coolant level, and inspect condition of cool-
ing system hoses and clamps after each 12 000-km
(7,500-miles).
Initially, coolant must be drained and cooling sys-
tem flushed and filled after the first 36 months of op-
eration. Thereafter, after each 24-months interval of
vehicle operation.
RECOMMENDED MAINTENANCE
The engine cooling system should be inspected for
proper operation and for component failure at least
every 12 months.
WARNING: IF THE ENGINE HAS BEEN RECENTLY
OPERATED, USE EXTREME CARE WHEN REMOV-
ING THE RADIATOR CAP TO AVOID SCALDING
WITH HOT, PRESSURIZED COOLANT.
For additional information, refer to Section 7, Cool-
ing System.COOLANT FREEZE PROTECTION
Jeeptcooling systems contain a 50/50 mixture of
anti-freeze and distilled water coolant. This is the
recommended coolant mixture for most ambient tem-
peratures. The factory-installed anti-freeze is formu-
lated to prevent corrosion on all cooling system metal
surfaces.
The degree of coolant freeze protection should be
tested every 12 months. If the coolant is contami-
nated orrustyin appearance, cooling system should
be drained and filled with a 50/50 mixture of fresh
coolant. For additional information, refer to Group
7ÐCooling System.
ENGINE AIR CLEANER FILTER ELEMENT
RECOMMENDED MAINTENANCE
Engine performance and fuel economy can be af-
fected by a restricted air cleaner filter. The filter
should be inspected on a regular basis for excessive
air restriction.
If the filter element is saturated with oil, replace
the filter element.
REQUIRED MAINTENANCE
Engine air cleaner filter must be replaced after
each 48 000-km (30,000-miles).
If a vehicle is frequently operated in dusty
areas, the air cleaner filter should be inspected
often.
FILTER ELEMENT SERVICE/REPLACEMENT
(1) Remove the air cleaner cover from the body/
housing (Fig. 9).
(2) Remove the air cleaner filter element from the
body/housing.
Fig. 9 Air Cleaner & Filter ElementÐ2.5L and 4.0L
Engines
0 - 16 LUBRICATION AND MAINTENANCEJ

BATTERY TESTING GENERAL INFORMATION
Before testing a battery, clean the top of the
battery case, posts and cable terminals.
Specific gravity is a ratio of the density of the elec-
trolyte and the density of pure water. The electrolyte
is composed of sulfuric acid and water. Acid makes
up approximately 35% of the electrolyte by weight,
or 24% by volume.
The condition of a battery may be determined from
the results of 2 tests:
²hydrometer test
²ability to supply current (battery load test)
Perform the hydrometer test first. If the specific
gravity is less than 1.235, (with battery at room tem-
perature) the battery must be charged before pro-
ceeding with further testing. A battery that will not
accept a charge is defective and further testing is not
necessary.
Completely discharged batteries may take sev-
eral hours to accept a charge. See Charging
Completely Discharged Battery.
A battery that has been fully charged but does not
pass the battery load test is defective.
A battery is fully charged when:
²all cells are gassing freely during charging
²3 corrected specific gravity tests, taken at 1-hour
intervals, indicate no increase in specific gravity.
ABNORMAL 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 due to equipment or accessories in-
stalled after delivery.
(4) Slow driving speeds (heavy traffic conditions)
or prolonged idling with high-amperage draw sys-
tems in use.
(5) Defective circuit or component causing excess
IOD. Refer to Ignition Off Draw Diagnosis in this
group.
(6) Defective charging system.
(7) Defective battery.
HYDROMETER TEST
Before performing a hydrometer test, remove
battery caps and check electrolyte level. Add
distilled water as required.
Before testing, visually inspect battery for any
damage (cracked case or cover, loose post, etc.) that
would cause the battery to be defective. To use the
hydrometer correctly, hold it with the top surface of
the electrolyte at eye level. Refer to manufacturers
instructions for correct use of hydrometer.
Remove only enough electrolyte from the battery to
keep the float off the bottom of the hydrometer bar-
rel with pressure on the bulb released. Exercise care
when inserting the tip of the hydrometer into a cellto avoid damage to the separators. Damaged separa-
tors can cause premature battery failure.
Hydrometer floats are generally calibrated to indi-
cate the specific gravity correctly only at one fixed
temperature, 80ÉF (26.6ÉC). When testing the specific
gravity at any other temperature, a correction factor
is required.
The correction factor is approximately a specific
gravity value of 0.004, referred to as 4 points of spe-
cific gravity. For each 10ÉF above 80ÉF (5.5ÉC above
26.6ÉC), add 4 points. For each 10ÉF below 80ÉF
(5.5ÉC below 26.6ÉC), subtract 4 points. Always cor-
rect the specific gravity for temperature variation.
Test the specific gravity of the electrolyte in each
battery cell.
Example: A battery is tested at 10ÉF (-12.2ÉC) and
has a specific gravity of 1.240. Determine the actual
specific gravity as follows:
²Determine the number of degrees above or below
80ÉF:
80ÉF - 10ÉF = 70ÉF
²Divide the result above by 10:
70ÉF/10 = 7
²Multiply the result from the previous step by the
temperature correction factor (0.004):
7 x 0.004 = 0.028
²The temperature at testing was below 80ÉF, there-
fore the temperature correction is subtracted:
1.240 - 0.028 = 1.212
²The corrected specific gravity is 1.212.
The fully charged battery should have a tempera-
ture corrected specific gravity of 1.260 to 1.290.
If the specific gravity of all cells is above 1.235,
and cell variation is more than 50 points (0.050), it is
an indication that the battery is unserviceable.
If the specific gravity of one or more cells is less
than 1.235, charge the battery at a rate of approxi-
mately 5 amperes. Continue charging until 3 consec-
utive specific gravity tests, taken at 1 hour intervals,
are constant.
If the cell specific gravity variation is more than 50
points (0.050) after the charge period, replace the
battery.
When the specific gravity of all cells is above 1.235
and variation between cells is less than 50 points
(0.050), the battery may be tested under heavy load.
BATTERY OPEN CIRCUIT VOLTAGE TEST
A battery voltage (no load) test will show state of
charge of a battery that will pass the Battery Load
Test described in this section.Before proceeding
with this test or Battery Load Test, completely
charge battery as described in Battery Charging
in this section.
If a battery has a no load voltage reading of 12.4
volts or greater and will not endure a load test, it is
defective and should be replaced. Refer to Group 8B -
JBATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS 8A - 3

IGNITION SYSTEMS
CONTENTS
page page
COMPONENT IDENTIFICATION/SYSTEM
OPERATION.......................... 1
COMPONENT REMOVAL/INSTALLATION..... 20DIAGNOSTICS/SERVICE PROCEDURES....... 8
IGNITION SWITCH...................... 30
SPECIFICATIONS....................... 33
COMPONENT IDENTIFICATION/SYSTEM OPERATION
INDEX
page page
Automatic Shut Down (ASD) Relay............ 1
Camshaft Position Sensor................... 1
Crankshaft Position Sensor.................. 2
Distributors.............................. 3
Engine Coolant Temperature Sensor........... 4
General Information........................ 1Ignition Coil.............................. 4
Intake Manifold Air Temperature Sensor........ 5
Manifold Absolute Pressure (MAP) Sensor...... 5
Powertrain Control Module (PCM)............. 6
Throttle Position Sensor.................... 6
GENERAL INFORMATION
Throughout this group, references are made to par-
ticular vehicle models by alphabetical designation
(XJ or YJ) or by the particular vehicle nameplate. A
chart showing a breakdown of alphabetical designa-
tions is included in the Introduction group at the be-
ginning of this manual.
This section of the group, Component Identifica-
tion/System Operation, will discuss ignition system
operation and will identify ignition system compo-
nents.
For diagnostic procedures and adjustments, refer to
the Diagnostics/Service Procedures section of this
group.
For removal and installation of ignition system
components, refer to the Component Removal/Instal-
lation section of this group.
For other useful information, refer to On-Board Di-
agnostics in the General Diagnosis sections of Group
14, Fuel System in this manual.
For operation of the DRB Scan Tool, refer to the
appropriate Powertrain Diagnostic Procedures ser-
vice manual.
An Ignition specifications section is included at the
end of this group. A general Maintenance Schedule
(mileage intervals) for ignition related items can be
found in Group 0, Lubrication and Maintenance. This
schedule can also be found in the Owners Manual.
IGNITION SYSTEMS
A multi-port, fuel injected engine is used on all
models. The ignition system is controlled by the Pow-
ertrain Control Module (PCM) on all engines. The
PCM was formerly referred to as the SBEC or engine
controller.
The ignition system consists of:
²Spark Plugs
²Ignition Coil
²Secondary Ignition Cables
²Ignition distributor (contains rotor and camshaft
position sensor)
²Powertrain Control Module (PCM)
²Crankshaft Position Sensor
AUTOMATIC SHUT DOWN (ASD) RELAY
The automatic shut down (ASD) relay is located in
the Power Distribution Center (PDC) near the bat-
tery (Fig. 1 or 2). As one of its functions, it will sup-
ply battery voltage to the ignition coil. The ground
circuit for the ASD relay is controlled by the Power-
train Control Module (PCM). The PCM regulates
ASD relay operation by switching the ground circuit
on-and-off.
CAMSHAFT POSITION SENSOR
The camshaft position sensor is located in the igni-
tion distributor (Figs. 3 or 4) on all engines.
The camshaft position sensor contains a hall effect
device called a sync signal generator to generate a
fuel sync signal. This sync signal generator detects a
JIGNITION SYSTEMS 8D - 1

For diagnostics, refer to the appropriate Powertrain
Diagnostic Procedures service manual for operation
of the DRB scan tool.
SPARK PLUGS
For spark plug removal, cleaning, gap adjustment
and installation, refer to the Component Removal/In-
stallation section of this group.
Faulty carbon and/or gas fouled plugs generally
cause hard starting, but they will clean up at higher
engine speeds. Faulty plugs can be identified in a
number of ways: poor fuel economy, power loss, de-
crease in engine speed, hard starting and, in general,
poor engine performance.
Remove the spark plugs and examine them for
burned electrodes and fouled, cracked or broken por-
celain insulators. Keep plugs arranged in the order
in which they were removed from the engine. An iso-
lated plug displaying an abnormal condition indi-
cates that a problem exists in the corresponding
cylinder. Replace spark plugs at the intervals recom-
mended in the maintenance chart in Group 0, Lubri-
cation and Maintenance.
Spark plugs that have low mileage may be cleaned
and reused if not otherwise defective. Refer to the
following Spark Plug Condition section of this group.
CONDITION
NORMAL OPERATING
The few deposits present on the spark plug will
probably be light tan or slightly gray in color. This is
evident with most grades of commercial gasoline
(Fig. 24). There will not be evidence of electrode
burning. Gap growth will not average more than ap-
proximately 0.025 mm (.001 in) per 1600 km (1000
miles) of operation. Spark plugs that have normal
wear can usually be cleaned, have the electrodes
filed, have the gap set and then be installed.Some fuel refiners in several areas of the United
States have introduced a manganese additive (MMT)
for unleaded fuel. During combustion, fuel with
MMT causes the entire tip of the spark plug to be
coated with a rust colored deposit. This rust color can
be misdiagnosed as being caused by coolant in the
combustion chamber. Spark plug performance is not
affected by MMT deposits.
COLD FOULING/CARBON FOULING
Cold fouling is sometimes referred to as carbon
fouling. The deposits that cause cold fouling are ba-
sically carbon (Fig. 24). A dry, black deposit on one
or two plugs in a set may be caused by sticking
valves or defective spark plug cables. Cold (carbon)
fouling of the entire set of spark plugs may be caused
by a clogged air filter or repeated short operating
times (short trips).
ELECTRODE GAP BRIDGING
Electrode gap bridging may be traced to loose de-
posits in the combustion chamber. These deposits ac-
cumulate on the spark plugs during continuous stop-
and-go driving. When the engine is suddenly
subjected to a high torque load, deposits partially liq-
uefy and bridge the gap between electrodes (Fig. 25).
This short circuits the electrodes. Spark plugs with
electrode gap bridging can be cleaned using standard
procedures.
SCAVENGER DEPOSITS
Fuel scavenger deposits may be either white or yel-
low (Fig. 26). They may appear to be harmful, but
this is a normal condition caused by chemical addi-
tives in certain fuels. These additives are designed to
change the chemical nature of deposits and decrease
spark plug misfire tendencies. Notice that accumula-
tion on the ground electrode and shell area may be
heavy, but the deposits are easily removed. Spark
Fig. 24 Normal Operation and Cold (Carbon) Fouling
Fig. 25 Electrode Gap Bridging
8D - 16 IGNITION SYSTEMSJ

LEAK-DOWN TEST
After cleaning and inspection, test each tappet for
specified leak-down rate tolerance to ensure zero-lash
operation (Fig. 12).
Swing the weighted arm of the hydraulic valve tap-
pet tester away from the ram of the Leak-Down
Tester 7980.
(1) Place a 7.925-7.950 mm (0.312-0.313 inch) di-
ameter ball bearing on the plunger cap of the tappet.
(2) Lift the ram and position the tappet (with the
ball bearing) inside the tester cup.
(3) Lower the ram, then adjust the nose of the ram
until it contacts the ball bearing. DO NOT tighten
the hex nut on the ram.
(4) Fill the tester cup with hydraulic valve tappet
test oil until the tappet is completely submerged.
(5) Swing the weighted arm onto the push rod and
pump the tappet plunger up and down to remove air.
When the air bubbles cease, swing the weighted arm
away and allow the plunger to rise to the normal po-
sition.
(6) Adjust the nose of the ram to align the pointer
with the SET mark on the scale of the tester and
tighten the hex nut.
(7) Slowly swing the weighted arm onto the push
rod.
(8) Rotate the cup by turning the handle at the
base of the tester clockwise one revolution every 2
seconds.
(9) Observe the leak-down time interval from the
instant the pointer aligns with the START mark on
the scale until the pointer aligns with the 0.125
mark. A normally functioning tappet will require 20-
110 seconds to leak-down. Discard tappets with leak-
down time interval not within this specification.
INSTALLATION
It is not necessary to charge the tappets with en-
gine oil. They will charge themselves within a very
short period of engine operation.(1) Dip each tappet in Mopar Engine Oil Supple-
ment, or equivalent.
(2) Use Hydraulic Valve Tappet Removal/Installa-
tion Tool C-4129-A to install each tappet in the same
bore from where it was originally removed.
(3) Install the exhaust and intake manifolds (refer
to Group 11, Exhaust System and Intake Manifold
for the proper procedure).
(4) Install the engine cylinder head and gasket.
(5) Install the push rods in their original locations.
(6) Install the rocker arms and bridge and pivot
assemblies at their original locations. Loosely install
the capscrews at each bridge.
(7) Tighten the capscrews alternately, one turn at
a time, to avoid damaging the bridges. Tighten the
capscrews to 28 Nzm (21 ft. lbs.) torque.
(8) Pour the remaining Mopar Engine Oil Supple-
ment, or equivalent over the entire valve actuating
assembly. The Mopar Engine Oil Supplement, or
equivalent must remain with the engine oil for at
least 1 609 km (1,000 miles). The oil supplement
need not be drained until the next scheduled oil
change.
(9) Install the engine cylinder head cover.
VALVE TIMING
Disconnect the spark plug wires and remove the
spark plugs.
Remove the engine cylinder head cover.
Remove the capscrews, bridge and pivot assembly,
and rocker arms from above the No.1 cylinder.
Alternately loosen each capscrew, one turn at a
time, to avoid damaging the bridge.
Rotate the crankshaft until the No.6 piston is at
top dead center (TDC) on the compression stroke.
Rotate the crankshaft counterclockwise (viewed
from the front of the engine) 90É.
Install a dial indicator on the end of the No.1 cyl-
inder intake valve push rod. Use rubber tubing to se-
cure the indicator stem on the push rod.
Set the dial indicator pointer at zero.
Rotate the crankshaft clockwise (viewed from the
front of the engine) until the dial indicator pointer
indicates 0.305 mm (0.012 inch) travel distance (lift).
The timing notch index on the vibration damper
should be aligned with the TDC mark on the timing
degree scale.
If the timing notch is more than 13 mm (1/2 inch)
away from the TDC mark in either direction, the
valve timing is incorrect.
If the valve timing is incorrect, the cause may be a
broken camshaft pin. It is not necessary to replace
the camshaft because of pin failure. A spring pin is
available for service replacement.
Fig. 12 Leak-Down Tester 7980
9 - 66 4.0L ENGINEJ