carb DODGE RAM 2001 Service Repair Manual

LUBRICATION & MAINTENANCE
TABLE OF CONTENTS
page page
LUBRICATION & MAINTENANCE
DESCRIPTION............................1
INTERNATIONAL SYMBOLS
DESCRIPTION............................3
PARTS & LUBRICANT RECOMMENDATION
STANDARD PROCEDURE...................3
FLUID TYPES
DESCRIPTION............................3
OPERATION.............................5
FLUID CAPACITIES
SPECIFICATIONS.........................6MAINTENANCE SCHEDULES
DESCRIPTION............................7
JUMP STARTING
STANDARD PROCEDURE..................27
HOISTING
STANDARD PROCEDURE..................28
TOWING
STANDARD PROCEDURE..................29
LUBRICATION &
MAINTENANCE
DESCRIPTION - FUEL REQUIREMENTS - GAS
ENGINES
Your engine is designed to meet all emissions reg-
ulations and provide excellent fuel economy and per-
formance when using high quality unleaded gasoline
having an octane rating of 87. The use of premium
gasoline is not recommended. The use of premium
gasoline will provide no benefit over high quality reg-
ular gasoline, and in some circumstances may result
in poorer performance.
Light spark knock at low engine speeds is not
harmful to your engine. However, continued heavy
spark knock at high speeds can cause damage and
immediate service is required. Engine damage result-
ing from operation with a heavy spark knock may
not be covered by the new vehicle warranty.
Poor quality gasoline can cause problems such as
hard starting, stalling and hesitations. If you experi-
ence these symptoms, try another brand of gasoline
before considering service for the vehicle.
Over 40 auto manufacturers world-wide have
issued and endorsed consistent gasoline specifications
(the Worldwide Fuel Charter, WWFC) to define fuel
properties necessary to deliver enhanced emissions,
performance and durability for your vehicle. We rec-
ommend the use of gasolines that meet the WWFC
specifications if they are available.
REFORMULATED GASOLINE
Many areas of the country require the use of
cleaner burning gasoline referred to as ªreformulat-
edº gasoline. Reformulated gasoline contain oxygen-
ates, and are specifically blended to reduce vehicle
emissions and improve air quality.
We strongly supports the use of reformulated gas-
oline. Properly blended reformulated gasoline will
provide excellent performance and durability for the
engine and fuel system components.
GASOLINE/OXYGENATE BLENDS
Some fuel suppliers blend unleaded gasoline with
oxygenates such as 10% ethanol, MTBE, and ETBE.
Oxygenates are required in some areas of the country
during the winter months to reduce carbon monoxide
emissions. Fuels blended with these oxygenates may
be used in your vehicle.
CAUTION: DO NOT use gasoline containing METH-
ANOL. Gasoline containing methanol may damage
critical fuel system components.
MMT IN GASOLINE
MMT is a manganese-containing metallic additive
that is blended into some gasoline to increase octane.
Gasoline blended with MMT provide no performance
advantage beyond gasoline of the same octane number
without MMT. Gasoline blended with MMT reduce
spark plug life and reduce emission system perfor-
mance in some vehicles. We recommend that gasolines
free of MMT be used in your vehicle. The MMT con-
tent of gasoline may not be indicated on the gasoline
pump; therefore, you should ask your gasoline retailer
whether or not his/her gasoline contains MMT.
BR/BELUBRICATION & MAINTENANCE 0 - 1

For battery system maintenance schedules and
jump starting procedures, see the owner's manual in
the vehicle glove box. Optionally, refer to Lubrication
and Maintenance for the recommended battery main-
tenance schedules and for the proper battery jump
starting procedures. While battery charging can be
considered a maintenance procedure, the battery
charging procedures and related information are
located in the standard procedures section of this ser-
vice manual. This was done because the battery must
be fully-charged before any battery system diagnosis
or testing procedures can be performed. Refer to
Standard procedures for the proper battery charging
procedures.
OPERATION
The battery system is designed to provide a safe,
efficient, reliable and mobile means of producing,
delivering and storing electrical energy. This electri-
cal energy is required to operate the engine starting
system, as well as to operate many of the other vehi-
cle accessory systems for limited durations while the
engine and/or the charging system are not operating.
The battery system is also designed to provide a
reserve of electrical energy to supplement the charg-
ing system for short durations while the engine is
running and the electrical current demands of the
vehicle exceed the output of the charging system. In
addition to producing, delivering, and storing electri-
cal energy for the vehicle, the battery system serves
as a capacitor and voltage stabilizer for the vehicle
electrical system. It absorbs most abnormal or tran-
sient voltages caused by the switching of any of the
electrical components or circuits in the vehicle.
DIAGNOSIS AND TESTING - BATTERY SYSTEM
The battery, starting, and charging systems in the
vehicle operate with one another and must be tested
as a single complete system. In order for the engine
to start and the battery to charge properly, all of the
components that are used in these systems must per-
form within specifications. It is important that the
battery, starting, and charging systems be thoroughly
tested and inspected any time a battery needs to be
charged or replaced. The cause of abnormal battery
discharge, overcharging or early battery failure must
be diagnosed and corrected before a battery is
replaced and before a vehicle is returned to service.
The service information for these systems has been
separated within this service manual to make it eas-
ier to locate the specific information you are seeking.
However, when attempting to diagnose any of these
systems, it is important that you keep their interde-
pendency in mind.
The diagnostic procedures used for the battery,
starting, and charging systems include the most
basic conventional diagnostic methods, to the more
sophisticated On-Board Diagnostics (OBD) built into
the Powertrain Control Module (PCM). Use of an
induction-type milliampere ammeter, a volt/ohmme-
ter, a battery charger, a carbon pile rheostat (load
tester) and a 12-volt test lamp may be required. All
OBD-sensed systems are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trou-
ble Code (DTC). The PCM will store a DTC in elec-
tronic memory for any failure it detects. Refer to
Charging System for the proper charging system on-
board diagnostic test procedures.
8F - 2 BATTERY SYSTEMBR/BE
BATTERY SYSTEM (Continued)

²A faulty or incorrect starting system component.
Refer to Starting System for the proper starting sys-
tem diagnosis and testing procedures.
²A faulty or incorrect battery. Refer to Standard
Procedures for the proper battery diagnosis and test-
ing procedures. Refer to Battery System Specifica-
tions for the proper specifications.
CLEANING
The following information details the recommended
cleaning procedures for the battery and related com-
ponents. In addition to the maintenance schedules
found in this service manual and the owner's man-
ual, it is recommended that these procedures be per-
formed any time the battery or related components
must be removed for vehicle service.
(1) Clean the battery cable terminal clamps of all
corrosion. Remove any corrosion using a wire brush
or a post and terminal cleaning tool, and a sodium
bicarbonate (baking soda) and warm water cleaning
solution (Fig. 1).
(2) Clean the battery tray and battery holddown
hardware of all corrosion. Remove any corrosion
using a wire brush and a sodium bicarbonate (baking
soda) and warm water cleaning solution. Paint any
exposed bare metal.
(3) If the removed battery is to be reinstalled,
clean the outside of the battery case and the top
cover with a sodium bicarbonate (baking soda) and
warm water cleaning solution using a stiff bristleparts cleaning brush to remove any acid film (Fig. 2).
Rinse the battery with clean water. Ensure that the
cleaning solution does not enter the battery cells
through the vent holes. If the battery is being
replaced, refer to Battery Specifications for the facto-
ry-installed battery specifications. Confirm that the
replacement battery is the correct size and has the
correct ratings for the vehicle.
(4) Clean the battery thermal guard with a sodium
bicarbonate (baking soda) and warm water cleaning
solution using a stiff bristle parts cleaning brush to
remove any acid film.
(5) Clean any corrosion from the battery terminal
posts with a wire brush or a post and terminal
cleaner, and a sodium bicarbonate (baking soda) and
warm water cleaning solution (Fig. 3).
INSPECTION
The following information details the recommended
inspection procedures for the battery and related
components. In addition to the maintenance sched-
ules found in this service manual and the owner's
manual, it is recommended that these procedures be
performed any time the battery or related compo-
nents must be removed for vehicle service.
(1) Inspect the battery cable terminal clamps for
damage. Replace any battery cable that has a dam-
aged or deformed terminal clamp.
Fig. 1 Clean Battery Cable Terminal Clamp - Typical
1 - TERMINAL BRUSH
2 - BATTERY CABLE
Fig. 2 Clean Battery - Typical
1 - CLEANING BRUSH
2 - WARM WATER AND BAKING SODA SOLUTION
3 - BATTERY
BR/BEBATTERY SYSTEM 8F - 5
BATTERY SYSTEM (Continued)

See the Open-Circuit Voltage Table. This voltage
reading will indicate the battery state-of-charge, but
will not reveal its cranking capacity. If a battery has
an open-circuit voltage reading of 12.4 volts or
greater, it may be load tested to reveal its cranking
capacity. Refer to Standard Procedures for the proper
battery load test procedures.
OPEN CIRCUIT VOLTAGE TABLE
Open Circuit Voltage Charge Percentage
11.7 volts or less 0%
12.0 volts 25%
12.2 volts 50%
12.4 volts 75%
12.6 volts or more 100%
STANDARD PROCEDURE - LOAD TEST
A battery load test will verify the battery cranking
capacity. The test is based on the Cold Cranking
Amperage (CCA) rating of the battery. To determine
the battery CCA rating, see the label affixed to the
battery case or refer to Battery Specifications for the
proper factory-installed specifications.
WARNING: IF THE BATTERY SHOWS SIGNS OF
FREEZING, LEAKING OR LOOSE POSTS, DO NOT
TEST, ASSIST-BOOST, OR CHARGE. THE BATTERY
MAY ARC INTERNALLY AND EXPLODE. PERSONAL
INJURY AND/OR VEHICLE DAMAGE MAY RESULT.
WARNING: EXPLOSIVE HYDROGEN GAS FORMS IN
AND AROUND THE BATTERY. DO NOT SMOKE,
USE FLAME, OR CREATE SPARKS NEAR THE BAT-
TERY. PERSONAL INJURY AND/OR VEHICLE DAM-
AGE MAY RESULT.WARNING: THE BATTERY CONTAINS SULFURIC
ACID, WHICH IS POISONOUS AND CAUSTIC. AVOID
CONTACT WITH THE SKIN, EYES, OR CLOTHING.
IN THE EVENT OF CONTACT, FLUSH WITH WATER
AND CALL A PHYSICIAN IMMEDIATELY. KEEP OUT
OF THE REACH OF CHILDREN.
WARNING: IF THE BATTERY IS EQUIPPED WITH
REMOVABLE CELL CAPS, BE CERTAIN THAT EACH
OF THE CELL CAPS IS IN PLACE AND TIGHT
BEFORE THE BATTERY IS RETURNED TO SER-
VICE. PERSONAL INJURY AND/OR VEHICLE DAM-
AGE MAY RESULT FROM LOOSE OR MISSING
CELL CAPS.
Before proceeding with this test, completely charge
the battery. Refer to Standard Procedures for the
proper battery charging procedures.
(1) Disconnect and isolate both battery cables, neg-
ative cable first. The battery top and posts should be
clean. Refer to Battery System Cleaning for the
proper cleaning procedures.
(2) Connect a suitable volt-ammeter-load tester
(Fig. 12) to the battery posts (Fig. 13). See the
instructions provided by the manufacturer of the
tester you are using. Check the open-circuit voltage
(no load) of the battery. Refer to Standard Procedures
for the proper battery open-circuit voltage test proce-
dures. The battery open-circuit voltage must be 12.4
volts or greater.
(3) Rotate the load control knob (carbon pile rheo-
stat) to apply a 300 ampere load to the battery for
fifteen seconds, then return the control knob to the
Off position (Fig. 14). This will remove the surface
charge from the battery.
(4) Allow the battery to stabilize to open-circuit
voltage. It may take up to five minutes for the bat-
tery voltage to stabilize.
Fig. 11 Testing Open-Circuit Voltage - Typical
Fig. 12 Volt-Ammeter-Load Tester - Typical
8F - 14 BATTERY SYSTEMBR/BE
BATTERY (Continued)

STARTING
TABLE OF CONTENTS
page page
STARTING
DESCRIPTION...........................32
OPERATION.............................32
DIAGNOSIS AND TESTING.................33
STARTING SYSTEM.....................33
SPECIFICATIONS........................38
ENGINE STARTER MOTOR
DESCRIPTION...........................39
OPERATION.............................39
DIAGNOSIS AND TESTING.................39STARTERMOTOR......................39
REMOVAL..............................40
INSTALLATION...........................41
ENGINE STARTER MOTOR RELAY
DESCRIPTION...........................42
OPERATION.............................42
DIAGNOSIS AND TESTING.................42
STARTER RELAY.......................42
REMOVAL..............................43
INSTALLATION...........................43
STARTING
DESCRIPTION
The starting system consists of:
²Starter relay
²Starter motor (including an integral starter sole-
noid)
Other components to be considered as part of start-
ing system are:
²Battery
²Battery cables
²Ignition switch and key lock cylinder
²Clutch pedal position switch (manual transmis-
sion)
²Park/neutral position switch (automatic trans-
mission)
²Wire harnesses and connections.
The Battery, Starting, and Charging systems oper-
ate in conjunction with one another, and must be
tested as a complete system. For correct operation of
starting/charging systems, all components used in
these 3 systems must perform within specifications.
When attempting to diagnose any of these systems, it
is important that you keep their interdependency in
mind.
The diagnostic procedures used in each of these
groups include the most basic conventional diagnostic
methods, to the more sophisticated On-Board Diag-
nostics (OBD) built into the Powertrain Control Mod-
ule (PCM). Use of an induction-type milliampere
ammeter, volt/ohmmeter, battery charger, carbon pile
rheostat (load tester), and 12-volt test lamp may be
required.
Certain starting system components are monitored
by the PCM and may produce a Diagnostic Trouble
Code (DTC). Refer to Diagnostic Trouble Codes for
additional information and a list of codes.
OPERATION
The starting system components form two separate
circuits. A high-amperage feed circuit that feeds the
starter motor between 150 and 350 amperes (700
amperes - diesel engine), and a low-amperage control
circuit that operates on less than 20 amperes. The
high-amperage feed circuit components include the
battery, the battery cables, the contact disc portion of
the starter solenoid, and the starter motor. The low-
amperage control circuit components include the igni-
tion switch, the clutch pedal position switch (manual
transmission), the park/neutral position switch (auto-
matic transmission), the starter relay, the electro-
magnetic windings of the starter solenoid, and the
connecting wire harness components.
If the vehicle is equipped with a manual transmis-
sion, it has a clutch pedal position switch installed in
series between the ignition switch and the coil bat-
tery terminal of the starter relay. This normally open
switch prevents the starter relay from being ener-
gized when the ignition switch is turned to the
momentary Start position, unless the clutch pedal is
depressed. This feature prevents starter motor oper-
ation while the clutch disc and the flywheel are
engaged. The starter relay coil ground terminal is
always grounded on vehicles with a manual trans-
mission.
If the vehicle is equipped with an automatic trans-
mission, battery voltage is supplied through the low-
amperage control circuit to the coil battery terminal
of the starter relay when the ignition switch is
turned to the momentary Start position. The park/
neutral position switch is installed in series between
the starter relay coil ground terminal and ground.
This normally open switch prevents the starter relay
from being energized and the starter motor from
operating unless the automatic transmission gear
selector is in the Neutral or Park positions.
8F - 32 STARTINGBR/BE

ENGINE STARTER MOTOR
DESCRIPTION
The starter motors used for the 5.9L diesel engine
and the 8.0L gasoline engine available in this model
are not interchangeable with each other, or with the
starter motors used for the other available engines.
The starter motors used for the 3.9L, 5.2L and the
5.9L gasoline engines available in this model are
interchangeable.
The starter motor for the 5.9L diesel engine is
mounted with three screws to the flywheel housing
on the left side of the engine. The starter motor for
the 8.0L gasoline engine is mounted with two screws
to the flange on the left rear corner of the engine
block, while the starter motors for all of the other
engines are mounted with one screw, a stud and a
nut to the manual transmission clutch housing or
automatic transmission torque converter housing and
are located on the left side of the engine.
Each of these starter motors incorporates several
of the same features to create a reliable, efficient,
compact, lightweight and powerful unit. The electric
motors of all of these starters have four brushes con-
tacting the motor commutator, and feature four elec-
tromagnetic field coils wound around four pole shoes.
The 3.9L, 5.2L, 5.9L and 8.0L gasoline engine starter
motors are rated at 1.4 kilowatts (about 1.9 horse-
power) output at 12 volts, while the 5.9L diesel
engine starter motor is rated at 2.7 kilowatts (about
3.6 horsepower) output at 12 volts.
All of these starter motors are serviced only as a
unit with their starter solenoids, and cannot be
repaired. If either component is faulty or damaged,
the entire starter motor and starter solenoid unit
must be replaced.
OPERATION
These starter motors are equipped with a gear
reduction (intermediate transmission) system. The
gear reduction system consists of a gear that is inte-
gral to the output end of the electric motor armature
shaft that is in continual engagement with a larger
gear that is splined to the input end of the starter
pinion gear shaft. This feature makes it possible to
reduce the dimensions of the starter. At the same
time, it allows higher armature rotational speed and
delivers increased torque through the starter pinion
gear to the starter ring gear.
The starter motors for all engines are activated by
an integral heavy duty starter solenoid switch
mounted to the overrunning clutch housing. This
electromechanical switch connects and disconnects
the feed of battery voltage to the starter motor, also
engaging and disengaging the starter pinion gear
with the starter ring gear.All starter motors use an overrunning clutch and
starter pinion gear unit to engage and drive a starter
ring gear that is integral to the flywheel (manual
transmission), torque converter or torque converter
drive plate (automatic transmission) mounted on the
rear crankshaft flange.
DIAGNOSIS AND TESTING - STARTER MOTOR
Correct starter motor operation can be confirmed
by performing the following free running bench test.
This test can only be performed with starter motor
removed from vehicle. Refer to Starter Specifications
for starter motor specifications.
(1) Remove starter motor from vehicle. Refer to
Starter MotorRemoval and Installation.
(2) Mount starter motor securely in a soft-jawed
bench vise. The vise jaws should be clamped on
mounting flange of starter motor. Never clamp on
starter motor by field frame.
(3) Connect suitable volt-ampere tester and 12-volt
battery to starter motor in series, and set ammeter to
100 ampere scale (250 ampere scale for diesel engine
starters). See instructions provided by manufacturer
of volt-ampere tester being used.
(4) Install jumper wire from solenoid terminal to
solenoid battery terminal. The starter motor should
operate. If starter motor fails to operate, replace
faulty starter motor assembly.
(5) Adjust carbon pile load of tester to obtain free
running test voltage. Refer to Specifications for the
starter motor free running test voltage specifications.
(6) Note reading on ammeter and compare this
reading to free running test maximum amperage
draw. Refer to Specifications for starter motor free
running test maximum amperage draw specifica-
tions.
(7) If ammeter reading exceeds maximum amper-
age draw specification, replace faulty starter motor
assembly.
STARTER MOTOR SOLENOID
This test can only be performed with starter motor
removed from vehicle.
(1) Remove starter motor. Refer toStarter Motor
Removal and Installation.
(2) Disconnect wire from solenoid field coil termi-
nal.
(3) Check for continuity between solenoid terminal
and solenoid field coil terminal with continuity tester
(Fig. 7). There should be continuity. If OK, go to Step
4. If not OK, replace faulty starter motor assembly.
(4) Check for continuity between solenoid terminal
and solenoid case (Fig. 8). There should be continuity.
If not OK, replace faulty starter motor assembly.
BR/BESTARTING 8F - 39

removed). Then continue to slowly rotate engine
clockwise until indicating mark (Fig. 18) is aligned to
0 degree (TDC) mark on timing chain cover.
(1) Clean top of cylinder block for a good seal
between distributor base and block.
(2) Lightly oil the rubber o-ring seal on the distrib-
utor housing.
(3) Install rotor to distributor shaft.
(4) Position distributor into engine to its original
position. Engage tongue of distributor shaft with slot
in distributor oil pump drive gear. Position rotor to
the number one spark plug cable position.
(5) Install distributor holddown clamp and clamp
bolt. Do not tighten bolt at this time.(6) Rotate the distributor housing until rotor is
aligned to CYL. NO. 1 alignment mark on the cam-
shaft position sensor (Fig. 19) .
(7) Tighten clamp holddown bolt (Fig. 20) to 22.5
N´m (200 in. lbs.) torque.
(8) Connect camshaft position sensor wiring har-
ness to main engine harness.
(9) Install distributor cap. Tighten mounting
screws.
(10) Refer to the following, Checking Distributor
Position.
Checking Distributor Position
To verify correct distributor rotational position, the
DRB scan tool must be used.
WARNING: WHEN PERFORMING THE FOLLOWING
TEST, THE ENGINE WILL BE RUNNING. BE CARE-
FUL NOT TO STAND IN LINE WITH THE FAN
BLADES OR FAN BELT. DO NOT WEAR LOOSE
CLOTHING.
(1) Connect DRB scan tool to data link connector.
The data link connector is located in passenger com-
partment, below and to left of steering column.
(2) Gain access to SET SYNC screen on DRB.
(3) Follow directions on DRB screen and start
engine. Bring to operating temperature (engine must
be in ªclosed loopº mode).
(4) With engine running atidle speed, the words
IN RANGE should appear on screen along with 0É.
This indicates correct distributor position.
(5) If a plus (+) or a minus (-) is displayed next to
degree number, and/or the degree displayed is not
zero, loosen but do not remove distributor holddown
clamp bolt. Rotate distributor until IN RANGE
appears on screen. Continue to rotate distributor
until achieving as close to 0É as possible. After
adjustment, tighten clamp bolt to 22.5 N´m (200 in.
lbs.) torque.
The degree scale on SET SYNC screen of DRB is
referring to fuel synchronization only.It is not
referring to ignition timing.Because of this, do
not attempt to adjust ignition timing using this
method. Rotating distributor will have no effect on
ignition timing. All ignition timing values are con-
trolled by powertrain control module (PCM).
After testing, install air cleaner assembly.
DISTRIBUTOR CAP
DIAGNOSIS AND TESTING - DISTRIBUTOR
CAP
Remove the distributor cap and wipe it clean with
a dry lint free cloth. Visually inspect the cap for
cracks, carbon paths, broken towers or damaged
Fig. 19 Rotor Alignment Mark
1 - CAMSHAFT POSITION SENSOR ALIGNMENT MARK
2 - ROTOR
3 - DISTRIBUTOR
Fig. 20 Distributor Holddown Clamp
1 - CLAMP BOLT
2 - HOLDDOWN CLAMP
3 - DISTRIBUTOR HOUSING
8I - 12 IGNITION CONTROLBR/BE
DISTRIBUTOR (Continued)

rotor button (Fig. 21) or (Fig. 22). Also check for
white deposits on the inside (caused by condensation
entering the cap through cracks). Replace any cap
that displays charred or eroded terminals. The
machined surface of a terminal end (faces toward
rotor) will indicate some evidence of erosion from
normal operation. Examine the terminal ends for evi-
dence of mechanical interference with the rotor tip.DISTRIBUTOR ROTOR
DIAGNOSIS AND TESTING - DISTRIBUTOR
ROTOR
Visually inspect the rotor (Fig. 23) for cracks, evi-
dence of corrosion or the effects of arcing on the
metal tip. Also check for evidence of mechanical
interference with the cap. Some charring is normal
on the end of the metal tip. The silicone-dielectric-
varnish-compound applied to the rotor tip for radio
interference noise suppression, will appear charred.
This is normal.Do not remove the charred com-
pound.Test the spring for insufficient tension.
Replace a rotor that displays any of these adverse
conditions.
IGNITION COIL
DESCRIPTION - 3.9L/5.2L/5.9L
A single ignition coil is used. The coil is not oil
filled. The coil windings are embedded in an epoxy
compound. This provides heat and vibration resis-
tance that allows the coil to be mounted on the
engine.
DESCRIPTION - 8.0L
Two separate coil packs containing a total of five
independent coils are attached to a common mount-
ing bracket. They are located above the right engine
valve cover (Fig. 24). The coil packs are not oil filled.
The front coil pack contains three independent epoxy
Fig. 21 Cap InspectionÐExternalÐTypical
1 - BROKEN TOWER
2 - DISTRIBUTOR CAP
3 - CARBON PATH
4 - CRACK
Fig. 22 Cap InspectionÐInternalÐTypical
1 - CHARRED OR ERODED TERMINALS
2 - WORN OR DAMAGED ROTOR BUTTON
3 - CARBON PATH
Fig. 23 Rotor InspectionÐTypical
1 - INSUFFICIENT SPRING TENSION
2 - CRACKS
3 - EVIDENCE OF PHYSICAL CONTACT WITH CAP
4 - ROTOR TIP CORRODED
BR/BEIGNITION CONTROL 8I - 13
DISTRIBUTOR CAP (Continued)

SPARK PLUG
DESCRIPTION
The 3.9L V-6 and 5.2L/5.9L V-8 engines use resis-
tor type spark plugs. The 8.0L V-10 engine uses
inductive type spark plugs.
Spark plug resistance values range from 6,000 to
20,000 ohms (when checked with at least a 1000 volt
spark plug tester).Do not use an ohmmeter to
check the resistance values of the spark plugs.
Inaccurate readings will result.
OPERATION
To prevent possible pre-ignition and/or mechanical
engine damage, the correct type/heat range/number
spark plug must be used.
Always use the recommended torque when tighten-
ing spark plugs. Incorrect torque can distort the
spark plug and change plug gap. It can also pull the
plug threads and do possible damage to both the
spark plug and the cylinder head.
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. A sin-gle plug displaying an abnormal condition indicates
that a problem exists in the corresponding cylinder.
Replace spark plugs at the intervals recommended in
Group O, Lubrication and Maintenance
Spark plugs that have low mileage may be cleaned
and reused if not otherwise defective, carbon or oil
fouled. Also refer to Spark Plug Conditions.
CAUTION: Never use a motorized wire wheel brush
to clean the spark plugs. Metallic deposits will
remain on the spark plug insulator and will cause
plug misfire.
DIAGNOSIS AND TESTING - SPARK PLUG
CONDITIONS
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. 29). There will not be evidence of electrode
burning. Gap growth will not average more than
approximately 0.025 mm (.001 in) per 3200 km (2000
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 com-
bustion chamber. Spark plug performance may be
affected by MMT deposits.
Fig. 28 Spark Plug Cable OrderÐ8.0L V-10 Engine
Fig. 29 Normal Operation and Cold (Carbon) Fouling
1 - NORMAL
2 - DRY BLACK DEPOSITS
3 - COLD (CARBON) FOULING
8I - 16 IGNITION CONTROLBR/BE
IGNITION COIL (Continued)

COLD FOULING/CARBON FOULING
Cold fouling is sometimes referred to as carbon
fouling. The deposits that cause cold fouling are basi-
cally carbon (Fig. 29). 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 cleaner element or repeated short operat-
ing times (short trips).
WET FOULING OR GAS FOULING
A spark plug coated with excessive wet fuel or oil
is wet fouled. In older engines, worn piston rings,
leaking valve guide seals or excessive cylinder wear
can cause wet fouling. In new or recently overhauled
engines, wet fouling may occur before break-in (nor-
mal oil control) is achieved. This condition can usu-
ally be resolved by cleaning and reinstalling the
fouled plugs.
OIL OR ASH ENCRUSTED
If one or more spark plugs are oil or oil ash
encrusted (Fig. 30), evaluate engine condition for the
cause of oil entry into that particular combustion
chamber.
ELECTRODE GAP BRIDGING
Electrode gap bridging may be traced to loose
deposits in the combustion chamber. These deposits
accumulate 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. 31).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. 32). 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
plugs with scavenger deposits can be considered nor-
mal in condition and can be cleaned using standard
procedures.
Fig. 30 Oil or Ash Encrusted
Fig. 31 Electrode Gap Bridging
1 - GROUND ELECTRODE
2 - DEPOSITS
3 - CENTER ELECTRODE
Fig. 32 Scavenger Deposits
1 - GROUND ELECTRODE COVERED WITH WHITE OR
YELLOW DEPOSITS
2 - CENTER ELECTRODE
BR/BEIGNITION CONTROL 8I - 17
SPARK PLUG (Continued)