spark plugs replace DODGE RAM 2001 Service User Guide

²Inspect brake linings.
³Off-the-highway operation, trailer towing snow
plowing, prolonged operation with heavy loading,
especially in hot weather require the more frequent
transmission service indicated with an ³ in Schedule
ªBº. Perform these services if the vehicle is usually
operated under these conditions.
Inspection and service should also be performed
anytime a malfunction is observed or suspected.
DESCRIPTION - HEAVY DUTY ENGINE
(FEDERAL ONLY ± 2500 8.0L HD AND 3500
5.9L& 8.0L MODELS) MAINTENANCE
SCHEDULES
There are two maintenance schedules that show
proper service based on the conditions that the vehi-
cle is subjected to. Use the schedule that best
describes these conditions.
ScheduleªAº, lists all the scheduled maintenance
to be performed under normal operating conditions
for Heavy Duty vehicles.
ScheduleªBº, lists maintenance recommended for
Heavy Duty vehicles operated under the conditions
listed at the beginning of that schedule.
²Where time and mileage are listed, follow the
interval that occurs first.
At Each Stop For Fuel
²Check engine oil level, add as required.
²Check windshield washer solvent and add if
required.
²Clean windshield and wiper blades as required.
Once A Month
²Check tire pressure and look for unusual wear
or damage.
²Inspect battery and clean and tighten terminals
as required.
²Check fluid levels of coolant reservoir, power
steering and transmission and add as needed.
²Check all lights and all other electrical items for
correct operation.
²Inspect and clean wiper blades. Replace if
required.
At Each Oil Change
²Inspect exhaust system.
²Inspect brake hoses.
²Adjust rear brakes.
²Rotate the tires at each oil change interval
shown on schedule ªAº (6,000 Miles) or every other
interval shown on schedule ªBº (6,000 Miles).
²Check engine coolant level, hoses, and clamps.
²Lubricate steering linkage.
EMISSION CONTROL SYSTEM MAINTENANCE
The scheduled emission maintenance listed inbold
typeon the Maintenance Schedules, must be done at
the mileage specified to assure the continued proper
functioning of the emission control system. These,
and all other maintenance services included in this
manual, should be done to provide the best vehicle
performance and reliability. More frequent mainte-
nance may be needed for vehicles in severe operating
conditions such as dusty areas and very short trip
driving.
FLUID FILL LOCATIONS AND LUBRICATION
POINTS
The fluid fill/check locations and lubrication points
are located in each applicable group.
HEAVY DUTY SCHEDULE ªAº
6,000 miles (10 000 km) or at 6 months
²Change engine oil.
²Replace engine oil filter.
12,000 Miles (19 000 km) or at 12 months
²Change engine oil.
²Replace engine oil filter.
²Inspect engine air cleaner element, replace
as necessary (8.0L only).
18,000 Miles (29 000 km) or at 18 months
²Change engine oil.
²Replace engine oil filter.
²Inspect brake linings
²Inspect front wheel bearings. Clean and repack,
if required (4x4).
24,000 Miles (38 000 km) or at 24 months
²Change engine oil.
²Replace engine oil filter.
²Replace engine air cleaner element and air
pump filter.
²Clean and lubricate crankcase inlet air filter
(5.9L).
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.
²Inspect front wheel bearings. Clean and repack,
if required (4x2).
30,000 Miles (48 000 km) or at 30 months
²Change engine oil.
²Replace engine oil filter.
²Replace spark plugs.
36,000 Miles (58 000 km) or at 36 months
²Change engine oil.
²Replace engine oil filter.
BR/BELUBRICATION & MAINTENANCE 0 - 17
MAINTENANCE SCHEDULES (Continued)

²Drain and refill transfer case fluid.
²Inspect brake linings.
²Flush and replace engine coolant at 36 months,
regardless of mileage.
²Inspect front wheel bearings. Clean and repack,
if required (4x4).
²Inspect engine air cleaner element, replace
as necessary (8.0L only).
42,000 Miles (67 000 km) or at 42 months
²Change engine oil.
²Replace engine oil filter.
48,000 Miles (77 000 km) or at 48 months)
²Change engine oil.
²Replace engine oil filter.
²Replace engine air cleaner element and air
pump filter.
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.
²Clean and lubricate crankcase inlet air filter
(5.9L).
²Inspect front wheel bearings. Clean and repack,
if required (4x2).
²Flush and replace engine coolant if not done at
36 months.
54,000 Miles (86 000 km) or at 54 months
²Change engine oil.
²Replace engine oil filter.
²Inspect brake linings.
²Inspect front wheel bearings. Clean and repack,
if required (4x4).
60,000 Miles (96 000 km) or at 60 months
²Change engine oil.
²Replace engine oil filter.
²Replace ignition cables.
²Replace PCV valve (5.9L).*
²Replace distributor cap and rotor (5.9L
only).
²Replace spark plugs.
²Flush and replace engine coolant if it has been
30,000 miles (48 000 km) or 24 months since last
change.
²Inspect engine air cleaner element, replace
as necessary (8.0L only).
66,000 Miles (106 000 km) or at 66 months
²Change engine oil.
²Replace engine oil filter.
72,000 Miles (115 000 km) or at 72 months
²Change engine oil.
²Replace engine oil filter.
²Replace engine air cleaner element and air
pump filter.²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.
²Drain and refill transfer case fluid.
²Clean and lubricate crankcase inlet air filter
(5.9L).
²Inspect front wheel bearings. Clean and repack,
if required (all).
²Inspect brake linings.
78,000 Miles (125 000 km) or at 78 months
²Change engine oil.
²Replace engine oil filter.
²Flush and replace engine coolant if it has been
30,000 miles (48 000 km) or 24 months since last
change.
82,500 Miles (132 000 km) or at 82 months
²Replace oxygen sensor (5.9L only).*
84,000 Miles (134 000 km) or at 84 months
²Change engine oil.
²Replace engine oil filter.
²Flush and replace engine coolant if it has been
30,000 miles (48 000 km) or 24 months since last
change.
²Inspect engine air cleaner element, replace
as necessary (8.0L only).
90,000 Miles (144 000 km) or at 90 months
²Change engine oil.
²Replace engine oil filter.
²Replace spark plugs.
²Inspect brake linings.
²Inspect front wheel bearings. Clean and repack,
if required (4x4).
96,000 Miles (154 000 km) or at 96 months
²Change engine oil.
²Replace engine oil filter.
²Replace engine air cleaner element and air
pump filter.
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.
²Clean and lubricate crankcase inlet air filter
(5.9L).
²Inspect front wheel bearings. Clean and repack,
if required (4x2).
102,000 Miles (163 000 km) or at 102 months
²Change engine oil.
²Replace engine oil filter.
108,000 Miles (173 000 km) or at 108 months
²Change engine oil.
²Replace engine oil filter.
²Drain and refill transfer case fluid.
²Inspect brake linings.
0 - 18 LUBRICATION & MAINTENANCEBR/BE
MAINTENANCE SCHEDULES (Continued)

²Flush and replace engine coolant if it has been
30,000 miles (48 000 km) or 24 months since last
change.
²Inspect front wheel bearings. Clean and repack,
if required (4x4).
²Inspect engine air cleaner element, replace
as necessary (8.0L only).
*Requires Service Reminder Indicator Light. If so
equipped, these parts are to be replaced at the indi-
cated mileage or when the service reminder indicator
light remains on continuously with the key in the
ªONº position, whichever occurs first.
HEAVY DUTY SCHEDULE ªBº
Follow this schedule if the vehicle is usually oper-
ated under one or more of the following conditions.
²Frequent short trips driving less than 5 miles
(8km)
²Frequent driving in dusty conditions
²Frequent trailer towing
²Extensive idling
²More than 50% of the driving is at sustained
high speeds during hot weather, above 90ÉF (32ÉC)
3,000 Miles (5 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
6,000 Miles (10 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
9,000 Miles (14 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x2).
12,000 Miles (19 000 km)
²Change engine oil.
²Replace engine oil filter.
²Inspect engine air cleaner element and air
pump filter, replace as necessary.
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.³
²Change rear axle fluid.
²Change front axle fluid (4x4).
²Inspect brake linings.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
15,000 Miles (24 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
18,000 Miles (29 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
²Inspect front wheel bearings (4x2).
²Drain and refill transfer case fluid every 18,000
miles (4x4).
21,000 Miles (34 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
24,000 Miles (38 000 km)
²Change engine oil
²Replace engine oil filter.
²Replace engine air cleaner element and air
pump filter.
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.
²Change rear axle fluid.
²Change front axle fluid (4x4).
²Clean and lubricate crankcase inlet air filter
(5.9L).
²Inspect front wheel bearings. Clean and repack,
if required (4x2).
²Inspect brake linings.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
27,000 Miles (43 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x2).
30,000 Miles (48 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect PCV valve, replace as necessary
(5.9L).
²Replace spark plugs.
²Inspect front wheel bearings (4x4).
BR/BELUBRICATION & MAINTENANCE 0 - 19
MAINTENANCE SCHEDULES (Continued)

33,000 Miles (53 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
36,000 Miles (58 000 km)
²Change engine oil.
²Replace engine oil filter.
²Inspect engine air cleaner element and air
pump filter, replace as necessary.
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.³
²Drain and refill transfer case (4x4).
²Change rear axle fluid.
²Change front axle fluid (4x4).
²Inspect brake linings.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
²Inspect front wheel bearings (4x2).
39,000 Miles (62 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
42,000 Miles (67 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
45,000 Miles (72 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x2).
²Flush and replace engine coolant (36 months).
48,000 Miles (77 000 km)
²Change engine oil.
²Replace engine oil filter.
²Replace engine air cleaner element and air
pump filter.
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.
²Change rear axle fluid.
²Change front axle fluid (4x4).
²Clean and lubricate crankcase inlet air filter
(5.9L).
²Inspect front wheel bearings. Clean and repack,
if required (4x2).²Inspect brake linings.
²Flush and replace engine coolant.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
²Drain and refill transfer case fluid every 18,000
miles (4x4).
51,000 Miles (82 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
54,000 Miles (86 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
²Inspect front wheel bearings (4x2).
²Drain and refill transfer case (4x4).
57,000 Miles (91 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
60,000 Miles (96 000 km)
²Change engine oil.
²Replace engine oil filter.
²Inspect engine air cleaner element and air
pump filter, replace as necessary.
²Replace PCV valve (5.9L).*
²Replace distributor cap and rotor (5.9L).
²Replace ignition cables.
²Replace spark plugs.
²Clean EGR passages (5.9L if so equipped).*
²Replace EGR valve (5.9L if so equipped).*
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.³
²Change rear axle fluid.
²Change front axle fluid (4x4).
²Inspect brake linings.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
63,000 Miles (101 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x2).
0 - 20 LUBRICATION & MAINTENANCEBR/BE
MAINTENANCE SCHEDULES (Continued)

66,000 Miles (106 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
69,000 Miles (110 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
72, 000 Miles (115 000 km)
²Change engine oil.
²Replace engine oil filter.
²Replace engine air cleaner element and air
pump filter.
²Clean and lubricate crankcase inlet air filter
(5.9L).
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.
²Drain and refill transfer case fluid (4x4).
²Change rear axle fluid.
²Change front axle fluid (4x4).
²Inspect front wheel bearings. Clean and repack,
if required (4x2).
²Inspect brake linings.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
²Inspect front wheel bearings (4x2).
75,000 Miles (120 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
78,000 Miles (125 000 km)
²Change engine oil.
²Replace engine oil filter.
²Flush and replace engine coolant if it has been
30,000 miles (48 000 km) since last change.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
81,000 Miles (130 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x2).
82,500 Miles (132 000 km)
²Replace oxygen sensor (5.9L only).*
84,000 Miles (134 000 km)
²Change engine oil.
²Replace engine oil filter.
²Inspect engine air cleaner element and air
pump filter, replace as necessary.
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.³
²Change rear axle fluid.
²Change front axle fluid (4x4).
²Inspect brake linings.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
87,000 Miles (139 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
90,000 Miles (144 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect PCV valve, replace as necessary
(5.9L).
²Replace spark plugs.
²Inspect front wheel bearings (4x4).
²Inspect front wheel bearings (4x2).
²Drain and refill transfer case fluid (4x4).
93,000 Miles (149 000 km)
²Change engine oil.
²Replace engine oil filter.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
96,000 Miles (154 000 km)
²Change engine oil.
²Replace engine oil filter.
²Replace engine air cleaner element and air
pump filter.
²Drain and refill automatic transmission fluid.
Replace filter and adjust bands.
²Change rear axle fluid.
²Change front axle fluid (4x4).
²Clean and lubricate crankcase inlet air filter
(5.9L).
²Inspect front wheel bearings. Clean and repack,
if required (4x2).
²Inspect brake linings.
²Lubricate tie rod ends every 3,000 miles (5 000
km).
²Inspect front wheel bearings (4x4).
BR/BELUBRICATION & MAINTENANCE 0 - 21
MAINTENANCE SCHEDULES (Continued)

²Wiper motor.
If the source of RFI or EMI noise is identified as a
component on the vehicle (i.e., generator, blower
motor, etc.), the ground path for that component
should be checked. If excessive resistance is found in
any ground circuit, clean, tighten, or repair the
ground circuits or connections to ground as required
before considering any component replacement.
For service and inspection of secondary ignition
components, refer to Electrical, Ignition Control.
Inspect the following secondary ignition system com-
ponents:
²Distributor cap and rotor
²Ignition coil
²Spark plugs
²Spark plug wire routing and condition.
Reroute the spark plug wires or replace the faulty
components as required.
If the source of the RFI or EMI noise is identified
as two-way mobile radio or telephone equipment,
check the equipment installation for the following:
²Power connections should be made directly to
the battery, and fused as closely to the battery as
possible.
²The antenna should be mounted on the roof or
toward the rear of the vehicle. Remember that mag-
netic antenna mounts on the roof panel can adversely
affect the operation of an overhead console compass,
if the vehicle is so equipped.
²The antenna cable should be fully shielded coax-
ial cable, should be as short as is practical, and
should be routed away from the factory-installed
vehicle wire harnesses whenever possible.
²The antenna and cable must be carefully
matched to ensure a low Standing Wave Ratio
(SWR).
Fleet vehicles are available with an extra-cost RFI-
suppressed Powertrain Control Module (PCM). This
unit reduces interference generated by the PCM on
some radio frequencies used in two-way radio com-
munications. However, this unit will not resolve com-
plaints of RFI in the commercial AM or FM radio
frequency ranges.
ENGINE-TO-BODY GROUND
STRAP
REMOVAL
(1) Remove the screw that secures the engine-to-
body ground strap eyelet to the dash panel (Fig. 10).
(2) Remove the screw that secures the engine-to-
body ground strap eyelet to the back of the engine
cylinder head (Fig. 11) or (Fig. 12).
(3) For the right side only on vehicles equipped
with a 3.9L, 5.2L or 5.9L engine, remove the nut thatsecures the engine-to-body ground strap eyelet to the
right rear valve cover stud.
(4) Remove the engine-to-body ground strap from
the engine compartment.INSTALLATION
(1) Position the engine-to-body ground strap to the
back of the engine cylinder head.
(2) Install and tighten the screw that secures the
engine-to-body ground strap eyelet to the back of the
engine cylinder head. Tighten the screw to 3.9 N´m
(35 in. lbs.).
Fig. 10 Engine-To-Body Ground
1 - SCREWS (2)
2 - GROUND STRAPS
Fig. 11 Engine-To-Body Ground Strap Remove/
Install - V6 & V8 Engine
1 - GROUND STRAP
2 - NUT
3 - GROUND STRAP
4 - SCREW
5 - SCREW
BR/BEAUDIO 8A - 13
RADIO NOISE SUPPRESSION COMPONENTS (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)

CHIPPED ELECTRODE INSULATOR
A chipped electrode insulator usually results from
bending the center electrode while adjusting the
spark plug electrode gap. Under certain conditions,
severe detonation can also separate the insulator
from the center electrode (Fig. 33). Spark plugs with
this condition must be replaced.
PREIGNITION DAMAGE
Preignition damage is usually caused by excessive
combustion chamber temperature. The center elec-
trode dissolves first and the ground electrode dis-
solves somewhat latter (Fig. 34). Insulators appear
relatively deposit free. Determine if the spark plug
has the correct heat range rating for the engine.
Determine if ignition timing is over advanced or if
other operating conditions are causing engine over-
heating. (The heat range rating refers to the operat-
ing temperature of a particular type spark plug.
Spark plugs are designed to operate within specific
temperature ranges. This depends upon the thick-
ness and length of the center electrodes porcelain
insulator.)
SPARK PLUG OVERHEATING
Overheating is indicated by a white or gray center
electrode insulator that also appears blistered (Fig.
35). The increase in electrode gap will be consider-
ably in excess of 0.001 inch per 2000 miles of opera-
tion. This suggests that a plug with a cooler heat
range rating should be used. Over advanced ignition
timing, detonation and cooling system malfunctions
can also cause spark plug overheating.
REMOVAL
On 3.9L/5.2L/5.9L engines, spark plug cable heat
shields are pressed into the cylinder head to sur-
round each cable boot and spark plug (Fig. 36).
(1) Always remove spark plug or ignition coil
cables by grasping at the cable boot (Fig. 38). Turn
the cable boot 1/2 turn and pull straight back in a
steady motion. Never pull directly on the cable.
Internal damage to cable will result.
(2) Prior to removing the spark plug, spray com-
pressed air around the spark plug hole and the area
around the spark plug. This will help prevent foreign
material from entering the combustion chamber.
(3) Remove the spark plug using a quality socket
with a rubber or foam insert.
(4) Inspect the spark plug condition. Refer to
Spark Plug Condition in the Diagnostics and Testing
section of this group.
Fig. 33 Chipped Electrode Insulator
1 - GROUND ELECTRODE
2 - CENTER ELECTRODE
3 - CHIPPED INSULATOR
Fig. 34 Preignition Damage
1 - GROUND ELECTRODE STARTING TO DISSOLVE
2 - CENTER ELECTRODE DISSOLVED
Fig. 35 Spark Plug Overheating
1 - BLISTERED WHITE OR GRAY COLORED INSULATOR
8I - 18 IGNITION CONTROLBR/BE
SPARK PLUG (Continued)

CLEANING
The plugs may be cleaned using commercially
available spark plug cleaning equipment. After clean-
ing, file center electrode flat with a small point file or
jewelers file before adjusting gap.
CAUTION: Never use a motorized wire wheel brush
to clean spark plugs. Metallic deposits will remain
on spark plug insulator and will cause plug misfire.
INSTALLATION
Special care should be taken when installing spark
plugs into the cylinder head spark plug wells. Be
sure the plugs do not drop into the plug wells as elec-
trodes can be damaged.
Always tighten spark plugs to the specified torque.
Over tightening can cause distortion resulting in a
change in the spark plug gap or a cracked porcelain
insulator.
When replacing the spark plug and ignition coil
cables, route the cables correctly and secure them in
the appropriate retainers. Failure to route the cables
properly can cause the radio to reproduce ignition
noise. It could cause cross ignition of the spark plugs
or short circuit the cables to ground.
(1) Start the spark plug into the cylinder head by
hand to avoid cross threading.
(2) Tighten spark plugs to 35-41 N´m (26-30 ft.
lbs.) torque.
(3) Install spark plug cables over spark plugs.
SPARK PLUG CABLE
DESCRIPTION
Spark plug cables are sometimes referred to as sec-
ondary ignition wires.
OPERATION
The spark plug cables transfer electrical current
from the ignition coil(s) and/or distributor, to individ-
ual spark plugs at each cylinder. The resistive spark
plug cables are of nonmetallic construction. The
cables provide suppression of radio frequency emis-
sions from the ignition system.
DIAGNOSIS AND TESTING - SPARK PLUG
CABLES
Cable routing is important on certain engines. To
prevent possible ignition crossfire, be sure the cables
are clipped into the plastic routing looms. Try to pre-
vent any one cable from contacting another. Before
removing cables, note their original location and
routing. Never allow one cable to be twisted around
another.
Check the spark plug cable connections for good
contact at the coil(s), distributor cap towers, and
spark plugs. Terminals should be fully seated. The
insulators should be in good condition and should fit
tightly on the coil, distributor and spark plugs. Spark
plug cables with insulators that are cracked or torn
must be replaced.
Clean high voltage ignition cables with a cloth
moistened with a non-flammable solvent. Wipe the
cables dry. Check for brittle or cracked insulation.
On 3.9L/5.2L/5.9L engines, spark plug cable heat
shields are pressed into the cylinder head to sur-
round each spark plug cable boot and spark plug
(Fig. 37). These shields protect the spark plug boots
from damage (due to intense engine heat generated
by the exhaust manifolds) and should not be
removed. After the spark plug cable has been
installed, the lip of the cable boot should have a
small air gap to the top of the heat shield (Fig. 37).
TESTING
When testing secondary cables for damage with an
oscilloscope, follow the instructions of the equipment
manufacturer.
If an oscilloscope is not available, spark plug cables
may be tested as follows:
CAUTION: Do not leave any one spark plug cable
disconnected for longer than necessary during test-
ing. This may cause possible heat damage to the
catalytic converter. Total test time must not exceed
ten minutes.
Fig. 36 Heat ShieldsÐ3.9L/5.2L/5.9L Engines
1 - AIR GAP
2 - SPARK PLUG BOOT HEAT SHIELD
BR/BEIGNITION CONTROL 8I - 19
SPARK PLUG (Continued)

With the engine running, remove spark plug cable
from spark plug (one at a time) and hold next to a
good engine ground. If the cable and spark plug are
in good condition, the engine rpm should drop and
the engine will run poorly. If engine rpm does not
drop, the cable and/or spark plug may not be operat-
ing properly and should be replaced. Also check
engine cylinder compression.
With the engine not running, connect one end of a
test probe to a good ground. Start the engine and run
the other end of the test probe along the entire
length of all spark plug cables. If cables are cracked
or punctured, there will be a noticeable spark jump
from the damaged area to the test probe. The cable
running from the ignition coil to the distributor cap
can be checked in the same manner. Cracked, dam-
aged or faulty cables should be replaced with resis-
tance type cable. This can be identified by the words
ELECTRONIC SUPPRESSION printed on the cable
jacket.
Use an ohmmeter to test for open circuits, exces-
sive resistance or loose terminals. If equipped,
remove the distributor cap from the distributor.Do
not remove cables from cap.Remove cable from
spark plug. Connect ohmmeter to spark plug termi-
nal end of cable and to corresponding electrode in
distributor cap. Resistance should be 250 to 1000
Ohms per inch of cable. If not, remove cable from dis-
tributor cap tower and connect ohmmeter to the ter-
minal ends of cable. If resistance is not within
specifications as found in the SPARK PLUG CABLE
RESISTANCE chart, replace the cable. Test all spark
plug cables in this manner.
SPARK PLUG CABLE RESISTANCE
MINIMUM MAXIMUM
250 Ohms Per Inch 1000 Ohms Per Inch
3000 Ohms Per Foot 12,000 Ohms Per Foot
To test ignition coil-to-distributor cap cable, do not
remove the cable from the cap. Connect ohmmeter to
rotor button (center contact) of distributor cap and
terminal at ignition coil end of cable. If resistance is
not within specifications as found in the Spark Plug
Cable Resistance chart, remove the cable from the
distributor cap. Connect the ohmmeter to the termi-
nal ends of the cable. If resistance is not within spec-
ifications as found in the Spark Plug Cable
Resistance chart, replace the cable. Inspect the igni-
tion coil tower for cracks, burns or corrosion.
REMOVAL
CAUTION: When disconnecting a high voltage cable
from a spark plug or from the distributor cap, twist
the rubber boot slightly (1/2 turn) to break it loose
(Fig. 38). Grasp the boot (not the cable) and pull it
off with a steady, even force.
INSTALLATION
Install cables into the proper engine cylinder firing
order (Fig. 39), (Fig. 40) or (Fig. 41).
When replacing the spark plug and coil cables,
route the cables correctly and secure in the proper
retainers. Failure to route the cables properly can
cause the radio to reproduce ignition noise. It could
also cause cross ignition of the plugs or short circuit
the cables to ground.
Fig. 37 Heat ShieldsÐ3.9L/5.2L/5.9L Engines
1 - AIR GAP
2 - SPARK PLUG BOOT HEAT SHIELD
Fig. 38 Cable Removal
1 - SPARK PLUG CABLE AND BOOT
2 - SPARK PLUG BOOT PULLER
3 - TWIST AND PULL
4 - SPARK PLUG
8I - 20 IGNITION CONTROLBR/BE
SPARK PLUG CABLE (Continued)