spark plugs DODGE RAM 2003 Service Service Manual

DIAGNOSIS AND TESTINGÐENGINE DIAGNOSIS - LUBRICATION
CONDITION POSSIBLE CAUSES CORRECTION
OIL LEAKS 1. Gaskets and O-Rings. 1.
(a) Misaligned or damaged. (a) Replace as necessary.
(b) Loose fasteners, broken or
porous metal parts.(b) Tighten fasteners, Repair or
replace metal parts.
2. Crankshaft rear seal 2. Replace as necessary.
3. Crankshaft seal flange.
Scratched, nicked or grooved.3. Polish or replace crankshaft.
4. Oil pan flange cracked. 4. Replace oil pan.
5.Front cover seal, damaged or
misaligned.5. Replace seal.
6. Scratched or damaged vibration
damper hub.6. Polish or replace damper.
OIL PRESSURE DROP 1. Low oil level. 1. Check and correct oil level.
2. Faulty oil pressure sending unit. 2. Replace sending unit.
3. Low oil pressure. 3. Check pump and bearing
clearance.
4. Clogged oil filter. 4. Replace oil filter.
5. Worn oil pump. 5. Replace as necessary.
6. Thin or diluted oil. 6. Change oil and filter.
7. Excessive bearing clearance. 7. Replace as necessary.
8. Oil pump relief valve stuck. 8. Replace oil pump.
9. Oil pickup tube loose or
damaged.9. Replace as necessary.
OIL PUMPING AT RINGS; SPARK
PLUGS FOULING1. Worn or damaged rings. 1. Hone cylinder bores and replace
rings.
2. Carbon in oil ring slots. 2. Replace rings.
3. Incorrect ring size installed. 3. Replace rings.
4. Worn valve guides. 4. Ream guides and replace valves.
5. Leaking intake gasket. 5. Replace intake gaskets.
6. Leaking valve guide seals. 6. Replace valve guide seals.
9 - 230 ENGINE - 5.9LDR
ENGINE - 5.9L (Continued)

DIAGNOSIS AND TESTINGÐCYLINDER
COMPRESSION PRESSURE
The results of a cylinder compression pressure test
can be utilized to diagnose several engine malfunc-
tions.
Ensure the battery is completely charged and the
engine starter motor is in good operating condition.
Otherwise, the indicated compression pressures may
not be valid for diagnosis purposes.
(1) Clean the spark plug recesses with compressed
air.
(2) Remove the spark plugs (Refer to 8 - ELEC-
TRICAL/IGNITION CONTROL/SPARK PLUG -
REMOVAL).
(3) Secure the throttle in the wide-open position.
(4) Disconnect the ignition coil.
(5) Insert a compression pressure gauge and rotate
the engine with the engine starter motor for three
revolutions.
(6) Record the compression pressure on the third
revolution. Continue the test for the remaining cylin-
ders.
(Refer to 9 - ENGINE - SPECIFICATIONS) for the
correct engine compression pressures.
DIAGNOSIS AND TESTING - CYLINDER
COMBUSTION PRESSURE LEAKAGE
The combustion pressure leakage test provides an
accurate means for determining engine condition.
Combustion pressure leakage testing will detect:
²Exhaust and intake valve leaks (improper seat-
ing)
²Leaks between adjacent cylinders or into water
jacket²Any causes for combustion/compression pressure
loss
WARNING: DO NOT REMOVE THE RADIATOR CAP
WITH THE SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM HOT COOLANT CAN
OCCUR.
Check the coolant level and fill as required. DO
NOT install the radiator cap.
Start and operate the engine until it attains nor-
mal operating temperature, then turn OFF the
engine.
Remove the spark plugs.
Remove the oil filler cap.
Remove the air cleaner.
Calibrate the tester according to the manufactur-
er's instructions. The shop air source for testing
should maintain 483 kPa (70 psi) minimum, 1,379
kPa (200 psi) maximum and 552 kPa (80 psi) recom-
mended.
Perform the test procedure on each cylinder accord-
ing to the tester manufacturer's instructions. While
testing, listen for pressurized air escaping through
the throttle body, tailpipe or oil filler cap opening.
Check for bubbles in the radiator coolant.
All gauge pressure indications should be equal,
with no more than 25% leakage.
FOR EXAMPLE:At 552 kPa (80 psi) input pres-
sure, a minimum of 414 kPa (60 psi) should be main-
tained in the cylinder CYLINDER COMBUSTION
PRESSURE LEAKAGE DIAGNOSIS CHART.
CYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHART
CONDITION POSSIBLE CAUSE CORRECTION
AIR ESCAPES THROUGH
THROTTLE BODYIntake valve bent, burnt, or not
seated properlyInspect valve and valve seat.
Reface or replace, as necessary
AIR ESCAPES THROUGH
TAILPIPEExhaust valve bent, burnt, or not
seated properlyInspect valve and valve seat.
Reface or replace, as necessary
AIR ESCAPES THROUGH
RADIATORHead gasket leaking or cracked
cylinder head or blockRemove cylinder head and inspect.
Replace defective part
MORE THAN 50% LEAKAGE
FROM ADJACENT CYLINDERSHead gasket leaking or crack in
cylinder head or block between
adjacent cylindersRemove cylinder head and inspect.
Replace gasket, head, or block as
necessary
MORE THAN 25% LEAKAGE AND
AIR ESCAPES THROUGH OIL
FILLER CAP OPENING ONLYStuck or broken piston rings;
cracked piston; worn rings and/or
cylinder wallInspect for broken rings or piston.
Measure ring gap and cylinder
diameter, taper and out-of-round.
Replace defective part as necessary
DRENGINE - 5.9L 9 - 231
ENGINE - 5.9L (Continued)

(1) Perform the Fuel Pressure Release Procedure
(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY -
STANDARD PROCEDURE).
(2) Disconnect the negative cable(s) from the bat-
tery.
(3) Inspect air cleaner, induction system, and
intake manifold to ensure system is dry and clear of
foreign material.
(4) Place a shop towel around the spark plugs to
catch any fluid that may possibly be under pressure
in the cylinder head. Remove the spark plugs.
(5) With all spark plugs removed, rotate the crank-
shaft using a breaker bar and socket.
(6) Identify the fluid in the cylinders (coolant, fuel,
oil, etc.).
(7) Be sure all fluid has been removed from the
cylinders.
(8) Repair engine or components as necessary to
prevent this problem from occurring again.
(9) Squirt a small amount of engine oil into the
cylinders to lubricate the walls. This will prevent
damage on restart.
(10) Install new spark plugs. Tighten the spark
plugs to 41 N´m (30 ft. lbs.) torque.
(11) Drain engine oil. Remove and discard the oil
filter.
(12) Install the drain plug. Tighten the plug to 34
N´m (25 ft. lbs.) torque.
(13) Install a new oil filter.
(14) Fill engine crankcase with the specified
amount and grade of oil. (Refer to LUBRICATION &
MAINTENANCE - SPECIFICATIONS).
(15) Connect the negative cable(s) to the battery.
(16) Start the engine and check for any leaks.
STANDARD PROCEDURE - CYLINDER BORE
HONING
Before honing, stuff plenty of clean shop towels
under the bores and over the crankshaft to keep
abrasive materials from entering the crankshaft
area.
(1) Used carefully, the Cylinder Bore Sizing Hone
C-823, equipped with 220 grit stones, is the best tool
for this job. In addition to deglazing, it will reduce
taper and out-of-round, as well as removing light
scuffing, scoring and scratches. Usually, a few strokes
will clean up a bore and maintain the required lim-
its.
CAUTION: DO NOT use rigid type hones to remove
cylinder wall glaze.
(2) Deglazing of the cylinder walls may be done if
the cylinder bore is straight and round. Use a cylin-
der surfacing hone, Honing Tool C-3501, equipped
with 280 grit stones (C-3501-3810). about 20-60strokes, depending on the bore condition, will be suf-
ficient to provide a satisfactory surface. Using honing
oil C-3501-3880, or a light honing oil, available from
major oil distributors.
CAUTION: DO NOT use engine or transmission oil,
mineral spirits, or kerosene.
(3) Honing should be done by moving the hone up
and down fast enough to get a crosshatch pattern.
The hone marks should INTERSECT at 40É to 60É
for proper seating of rings (Fig. 3).
(4) A controlled hone motor speed between 200 and
300 RPM is necessary to obtain the proper cross-
hatch angle. The number of up and down strokes per
minute can be regulated to get the desired 40É to 60É
angle. Faster up and down strokes increase the cross-
hatch angle.
(5) After honing, it is necessary that the block be
cleaned to remove all traces of abrasive. Use a brush
to wash parts with a solution of hot water and deter-
gent. Dry parts thoroughly. Use a clean, white, lint-
free cloth to check that the bore is clean. Oil the
bores after cleaning to prevent rusting.
REMOVAL
(1) Disconnect the battery negative cable.
(2) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
Fig. 3 Cylinder Bore Crosshatch Pattern
1 - CROSSHATCH PATTERN
2 - INTERSECT ANGLE
DRENGINE - 5.9L 9 - 233
ENGINE - 5.9L (Continued)

OS-US Item Identification Location of
.127 mm adjacent to
two
(.005 in.) 3/89tapped
holes on
each
end of
cylinder
head.
TORQUE
TORQUE CHART 5.9L ENGINE
DESCRIPTION N´m Ft.
Lbs.In.
Lbs.
Camshaft Sprocket Bolt 68 50 Ð
Camshaft Thrust Plate Bolts 24 Ð 210
Timing Chain Case Cover
Bolts41 30 Ð
Connecting Rod Cap Bolts 61 45 Ð
Main Bearing Cap Bolts 115 85 Ð
Crankshaft Pulley Bolts 24 Ð 210
Cylinder Head Bolts
Step 1 68 50 Ð
Step 2 143 105 Ð
Cylinder Head Cover Bolts 11 Ð 95
Engine Support Bracket to
Block Bolts (4WD)41 30 Ð
Exhaust Manifold to Cylinder
Head Bolts/Nuts34 25 Ð
Flywheel Bolts 75 55 Ð
Front Insulator Through
bolt/nut95 70 Ð
Front Insulator to Support
Bracket
Stud Nut (4WD) 41 30 Ð
Through Bolt/Nut (4WD) 102 75 Ð
Front Insulator to Block Bolts
(2WD)95 70 Ð
Generator Mounting Bolt 41 30 Ð
Intake Manifold Bolts Refer to Procedure
Oil Pan Bolts 24 Ð 215
Oil Pan Drain Plug 34 25 Ð
Oil Pump Attaching Bolts 41 30 Ð
Oil Pump Cover Bolts 11 Ð 95
DESCRIPTION N´m Ft.
Lbs.In.
Lbs.
Rear Insulator to Bracket
Through-Bolt (2WD)68 50 Ð
Rear Insulator to
Crossmember Support
Bracket Nut (2WD)41 30 Ð
Rear Insulator to
Crossmember Nuts (4WD)68 50 Ð
Rear Insulator to
Transmission Bolts (4WD)68 50 Ð
Rear Insulator Bracket Bolts
(4WD Automatic)68 50 Ð
Rear Support Bracket to
Crossmember Flange Nuts41 30 Ð
Rear Support Plate to
Transfer Case Bolts41 30 Ð
Rocker Arm Bolts 28 21 Ð
Spark Plugs 41 30 Ð
Starter Motor Mounting Bolts 68 50 Ð
Thermostat Housing Bolts 25 Ð 225
Throttle Body Bolts 23 Ð 200
Torque Converter Drive Plate
Bolts31 Ð 270
Transfer Case to Insulator
Mounting Plate Nuts204 105 Ð
Transmission Support Bracket
Bolts (2WD)68 50 Ð
Vibration Damper Bolt 244 180 Ð
Water Pump to Timing Chain
Case Cover Bolts41 30 Ð
DRENGINE - 5.9L 9 - 239
ENGINE - 5.9L (Continued)

CYLINDER HEAD
DESCRIPTION
DESCRIPTIONÐCYLINDER HEAD
The cast iron cylinder heads (Fig. 6) are mounted
to the cylinder block using ten bolts. The spark plugs
are located in the peak of the wedge between the
valves.
DESCRIPTION - CYLINDER HEAD COVER
GASKET
The cylinder head cover gasket (Fig. 7) is a steel-
backed silicone gasket, designed for long life usage.
OPERATION
OPERATIONÐCYLINDER HEAD
The cylinder head closes the combustion chamber
allowing the pistons to compress the air fuel mixture
to the correct ratio for ignition. The valves located in
the cylinder head open and close to either allow clean
air into the combustion chamber or to allow the
exhaust gases out, depending on the stroke of the
engine.
OPERATION - CYLINDER HEAD COVER
GASKET
The steel-backed silicone gasket is designed to seal
the cylinder head cover for long periods of time
through extensive heat and cold, without failure. The
gasket is designed to be reusable.
DIAGNOSIS AND TESTINGÐCYLINDER HEAD
GASKET FAILURE
A cylinder head gasket leak can be located between
adjacent cylinders or between a cylinder and the
adjacent water jacket.
²Possible indications of the cylinder head gasket
leaking between adjacent cylinders are:
þ Loss of engine power
þ Engine misfiring
þ Poor fuel economy
²Possible indications of the cylinder head gasket
leaking between a cylinder and an adjacent water
jacket are:
þ Engine overheating
þ Loss of coolant
þ Excessive steam (white smoke) emitting from
exhaust
þ Coolant foaming
CYLINDER-TO-CYLINDER LEAKAGE TEST
To determine if an engine cylinder head gasket is
leaking between adjacent cylinders, follow the proce-
dures in Cylinder Compression Pressure Test in this
section. An engine cylinder head gasket leaking
between adjacent cylinders will result in approxi-
mately a 50±70% reduction in compression pressure.
CYLINDER-TO-WATER JACKET LEAKAGE TEST
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING WITH COOLANT PRES-
SURE CAP REMOVED.
VISUAL TEST METHOD
With the engine cool, remove the coolant pressure
cap. Start the engine and allow it to warm up until
thermostat opens.
Fig. 6 Cylinder Head AssemblyÐV-8 Gas Engines
1 - EXHAUST VALVE
2 - SPARK PLUGS
3 - EXHAUST VALVES
4 - SPARK PLUGS
5 - EXHAUST VALVE
6 - INTAKE VALVES
7 - INTAKE VALVES
Fig. 7 Cylinder Head Cover Gasket V-8 Gas Engines
1 - CYLINDER HEAD COVER GASKET
DRENGINE - 5.9L 9 - 243

If a large combustion/compression pressure leak
exists, bubbles will be visible in the coolant.
COOLING SYSTEM TESTER METHOD
WARNING: WITH COOLING SYSTEM TESTER IN
PLACE, PRESSURE WILL BUILD UP FAST. EXCES-
SIVE PRESSURE BUILT UP, BY CONTINUOUS
ENGINE OPERATION, MUST BE RELEASED TO A
SAFE PRESSURE POINT. NEVER PERMIT PRES-
SURE TO EXCEED 138 kPa (20 psi).
Install Cooling System Tester 7700 or equivalent to
pressure cap neck. Start the engine and observe the
tester's pressure gauge. If gauge pulsates with every
power stroke of a cylinder a combustion pressure
leak is evident.
CHEMICAL TEST METHOD
Combustion leaks into the cooling system can also
be checked by using Bloc-Chek Kit C-3685-A or
equivalent. Perform test following the procedures
supplied with the tool kit.
REMOVAL
(1) Disconnect the battery negative cable.
(2) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(3) Remove the air cleaner resonator and duct
work.
(4) Remove the intake manifold-to-generator
bracket support rod. Remove the generator.
(5) Remove closed crankcase ventilation system.
(6) Disconnect the evaporation control system.
(7) Perform the Fuel System Pressure Release pro-
cedure (Refer to 14 - FUEL SYSTEM/FUEL DELIV-
ERY - STANDARD PROCEDURE). Disconnect the
fuel supply line (Refer to 14 - FUEL SYSTEM/FUEL
DELIVERY/QUICK CONNECT FITTING - STAN-
DARD PROCEDURE).
(8) Disconnect accelerator linkage and if so
equipped, the speed control and transmission kick-
down cables.
(9) Remove distributor cap and wires.
(10) Disconnect the coil wires.
(11) Disconnect heat indicator sending unit wire.
(12) Disconnect heater hoses and bypass hose.
(13) Remove the master cylinder and booster
assembly. Refer to section 5 brakes.
(14) Remove cylinder head covers and gaskets
(Refer to 9 - ENGINE/CYLINDER HEAD/CYLIN-
DER HEAD COVER(S) - REMOVAL).
(15) Remove intake manifold (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
REMOVAL) and throttle body as an assembly. Dis-
card the flange side gaskets and the front and rear
cross-over gaskets.(16) Remove exhaust manifolds (Refer to 9 -
ENGINE/MANIFOLDS/EXHAUST MANIFOLD -
REMOVAL).
(17) Remove rocker arm assemblies and push rods.
Identify to ensure installation in original locations.
(18) Remove the head bolts from each cylinder
head and remove cylinder heads. Discard the cylin-
der head gasket.
(19) Remove spark plugs.
CLEANING
Clean all surfaces of cylinder block and cylinder
heads.
Clean cylinder block front and rear gasket surfaces
using a suitable solvent.
INSPECTION
Inspect all surfaces with a straightedge if there is
any reason to suspect leakage. If out-of-flatness
exceeds 0.00075mm/mm (0.0001in/in.) times the span
length in any direction, either replace head or lightly
machine the head surface.
FOR EXAMPLE:ÐA 305 mm (12 in.) span is
0.102 mm (0.004 in.) out-of-flat. The allowable out-of-
flat is 305 x 0.00075 (12 x 0.00075) equals 0.23 mm
(0.009 in.). This amount of out-of-flat is acceptable.
The cylinder head surface finish should be
1.78-3.00 microns (70-125 microinches).
Inspect push rods. Replace worn or bent rods.
INSTALLATION
(1) Clean all surfaces of cylinder block and cylin-
der heads.
(2) Clean cylinder block front and rear gasket sur-
faces using a suitable solvent.
(3) Position new cylinder head gaskets onto the
cylinder block.
(4) Position cylinder heads onto head gaskets and
cylinder block.
(5) Starting at top center, tighten all cylinder head
bolts, in sequence (Fig. 8).
CAUTION: When tightening the rocker arm bolts,
make sure the piston in that cylinder is NOT at
TDC. Contact between the valves and piston could
occur.
(6) Install push rods and rocker arm assemblies in
their original position. Tighten the bolts to 28 N´m
(21 ft. lbs.) torque.
(7) Install the intake manifold (Refer to 9 -
ENGINE/MANIFOLDS/INTAKE MANIFOLD -
INSTALLATION) and throttle body assembly.
(8) Install exhaust manifolds (Refer to 9 -
ENGINE/MANIFOLDS/EXHAUST MANIFOLD -
INSTALLATION).
9 - 244 ENGINE - 5.9LDR
CYLINDER HEAD (Continued)

(9) If required, adjust spark plugs to specifications.
Install the plugs and tighten to 41 N´m (30 ft. lbs.)
torque.
(10) Install coil wire.
(11) Connect heat indicator sending unit wire.
(12) Connect the heater hoses and bypass hose.
(13) Install distributor cap and wires.
(14) Connect the accelerator linkage and if so
equipped, the speed control and transmission kick-
down cables.
(15) Install the fuel supply line (Refer to 14 -
FUEL SYSTEM/FUEL DELIVERY/QUICK CON-
NECT FITTING - STANDARD PROCEDURE).
(16) Install the generator and drive belt (Refer to 7
- COOLING/ACCESSORY DRIVE/DRIVE BELTS -
INSTALLATION). Tighten generator mounting bolt
to 41 N´m (30 ft. lbs.) torque. Tighten the adjusting
strap bolt to 23 N´m (200 in. lbs.) torque.
(17) Install the intake manifold-to-generator
bracket support rod. Tighten the bolts.
(18) Place the cylinder head cover gaskets in posi-
tion and install cylinder head covers (Refer to 9 -
ENGINE/CYLINDER HEAD/CYLINDER HEAD
COVER(S) - INSTALLATION).
(19) Install closed crankcase ventilation system.
(20) Connect the evaporation control system.
(21) Reinstall the master cylinder and booster
assembly. Refer to section 5 brakes.
(22) Install the air cleaner.
(23) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(24) Connect the negative cable to the battery.
(25) Start engine check for leaks.
CYLINDER HEAD COVER(S)
REMOVAL
NOTE: A steel backed silicon gasket is used with
the cylinder head cover (Fig. 9). This gasket can be
used again.
(1) Disconnect the negative cable from the battery.
(2) Disconnect the spark plug wires form the spark
plugs and set aside.
(3) Disconnect closed ventilation system and evap-
oration control system from cylinder head cover.
(4) Remove cylinder head cover and gasket.
CLEANING
Clean cylinder head cover gasket surface.
Clean head rail, if necessary.
INSPECTION
Inspect cover for distortion and straighten, if nec-
essary.
Check the gasket for use in head cover installation.
If damaged, use a new gasket.
INSTALLATION
(1) The cylinder head cover gasket can be used
again. Install the gasket onto the head rail.
(2) Position the cylinder head cover onto the gas-
ket. Tighten the bolts to 11 N´m (95 in. lbs.) torque.
(3) Install closed crankcase ventilation system and
evaporation control system.
(4) Connect the spark plug wires to the spark
plugs.
(5) Connect the negative cable to the battery.
Fig. 8 Cylinder Head Bolt Tightening Sequence
Fig. 9 Cylinder Head Cover Gasket
1 - CYLINDER HEAD COVER GASKET
DRENGINE - 5.9L 9 - 245
CYLINDER HEAD (Continued)

DIAGNOSIS AND TESTINGÐENGINE DIAGNOSIS - PERFORMANCE
PERFORMANCE DIAGNOSIS CHARTÐGASOLINE ENGINES
CONDITION POSSIBLE CAUSES CORRECTION
ENGINE WILL NOT CRANK 1. Weak or dead battery 1. Charge/Replace Battery. (Refer to 8 -
ELECTRICAL/BATTERY SYSTEM/
BATTERY - STANDARD PROCEDURE).
Check charging system. (Refer to 8 -
ELECTRICAL/CHARGING - DIAGNOSIS
AND TESTING).
2. Corroded or loose battery connections 2. Clean/tighten suspect battery/starter
connections
3. Faulty starter or related circuit(s) 3. Check starting system. (Refer to 8 -
ELECTRICAL/STARTING - DIAGNOSIS
AND TESTING)
4. Seized accessory drive component 4. Remove accessory drive belt and
attempt to start engine. If engine starts,
repair/replace seized component.
5. Engine internal mechanical failure or
hydro-static lock5. Refer to (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
ENGINE CRANKS BUT
WILL NOT START1. No spark 1. Check for spark. (Refer to 8 -
ELECTRICAL/IGNITION CONTROL -
DESCRIPTION)
2. No fuel 2. Perform fuel pressure test, and if
necessary, inspect fuel injector(s) and
driver circuits. (Refer to 14 - FUEL
SYSTEM/FUEL DELIVERY/FUEL PUMP -
DIAGNOSIS AND TESTING).
3. Low or no engine compression 3. Perform cylinder compression pressure
test. (Refer to 9 - ENGINE - DIAGNOSIS
AND TESTING).
ENGINE LOSS OF POWER 1. Worn or burned distributor rotor 1. Install new distributor rotor
2. Worn distributor shaft 2. Remove and repair distributor (Refer to
8 - ELECTRICAL/IGNITION CONTROL/
DISTRIBUTOR - REMOVAL).
3. Worn or incorrect gapped spark plugs 3. Clean plugs and set gap. (Refer to 8 -
ELECTRICAL/IGNITION CONTROL/
SPARK PLUG - CLEANING).
4. Dirt or water in fuel system 4. Clean system and replace fuel filter
5. Faulty fuel pump 5. Install new fuel pump
6. Incorrect valve timing 6. Correct valve timing
7. Blown cylinder head gasket 7. Install new cylinder head gasket
8. Low compression 8. Test cylinder compression (Refer to 9 -
ENGINE - DIAGNOSIS AND TESTING).
9. Burned, warped, or pitted valves 9. Install/Reface valves as necessary
10. Plugged or restricted exhaust system 10. Install new parts as necessary
11. Faulty ignition cables 11. Replace any cracked or shorted cables
9 - 354 ENGINE 8.0LDR
ENGINE 8.0L (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
12. Faulty ignition coil 12. Test and replace, as necessary (Refer
to 8 - ELECTRICAL/IGNITION CONTROL/
IGNITION COIL - REMOVAL).
ENGINE STALLS OR
ROUGH IDLE1. Carbon build-up on throttle plate 1. Remove throttle body and de-carbon.
(Refer to 14 - FUEL SYSTEM/FUEL
INJECTION/THROTTLE BODY -
REMOVAL).
2. Engine idle speed too low 2. Check Idle Air Control circuit. (Refer to
14 - FUEL SYSTEM/FUEL INJECTION/
IDLE AIR CONTROL MOTOR -
DESCRIPTION)
3. Worn or incorrectly gapped spark plugs 3. Replace or clean and re-gap spark
plugs (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG -
CLEANING)
4. Worn or burned distributor rotor 4. Install new distributor rotor
5. Spark plug cables defective or crossed 5. Check for correct firing order or replace
spark plug cables. (Refer to 8 -
ELECTRICAL/IGNITION CONTROL/
SPARK PLUG CABLE - DIAGNOSIS AND
TESTING)
6. Faulty coil 6. Test and replace, if necessary (Refer to
8 - ELECTRICAL/IGNITION CONTROL/
IGNITION COIL - REMOVAL)
7. Intake manifold vacuum leak 7. Inspect intake manifold gasket and
vacuum hoses (Refer to 9 - ENGINE/
MANIFOLDS/INTAKE MANIFOLD -
DIAGNOSIS AND TESTING).
ENGINE MISSES ON
ACCELERATION1. Worn or incorrectly gapped spark plugs 1. Replace spark plugs or clean and set
gap. (Refer to 8 - ELECTRICAL/IGNITION
CONTROL/SPARK PLUG - CLEANING)
2. Spark plug cables defective or crossed 2. Replace or rewire secondary ignition
cables. (Refer to 8 - ELECTRICAL/
IGNITION CONTROL/SPARK PLUG
CABLE - REMOVAL)
3. Dirt in fuel system 3. Clean fuel system
4. Burned, warped or pitted valves 4. Install new valves
5. Faulty coil 5. Test and replace as necessary (Refer to
8 - ELECTRICAL/IGNITION CONTROL/
IGNITION COIL - REMOVAL)
DRENGINE 8.0L 9 - 355
ENGINE 8.0L (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
4. Excessive main bearing clearance 4. Measure bearings for correct
clearance. Repair as necessary
5. Excessive end play 5. Check crankshaft thrust bearing for
excessive wear on flanges
6. Crankshaft main journal out of round
or worn6. Grind journals or replace crankshaft
7. Loose flywheel or torque converter 7. Inspect crankshaft, flexplate/flywheel
and bolts for damage. Tighten to correct
torque
LOW OIL PRESSURE 1. Low oil level 1. Check oil level and fill if necessary
2. Faulty oil pressure sending unit 2. Install new sending unit
3. Clogged oil filter 3. Install new oil filter
4. Worn oil pump 4. Replace oil pump assembly.
5. Thin or diluted oil 5. Change oil to correct viscosity.
6. Excessive bearing clearance 6. Measure bearings for correct
clearance
7. Oil pump relief valve stuck 7. Remove valve to inspect, clean and
reinstall
8. Oil pickup tube loose, broken, bent or
clogged8. Inspect oil pickup tube and pump, and
clean or replace if necessary
9. Oil pump cover warped or cracked 9. Install new oil pump
OIL LEAKS 1. Misaligned or deteriorated gaskets 1. Replace gasket
2. Loose fastener, broken or porous
metal part2. Tighten, repair or replace the part
3. Front or rear crankshaft oil seal
leaking3. Replace seal
4. Leaking oil gallery plug or cup plug 4. Remove and reseal threaded plug.
Replace cup style plug
EXCESSIVE OIL
CONSUMPTION OR
SPARK PLUGS OIL
FOULED1. CCV System malfunction 1. (Refer to 25 - EMISSIONS
CONTROL/EVAPORATIVE EMISSIONS
- DESCRIPTION) for correct operation
2. Defective valve stem seal(s) 2. Repair or replace seal(s)
3. Worn or broken piston rings 3. Hone cylinder bores. Install new rings
4. Scuffed pistons/cylinder walls 4. Hone cylinder bores and replace
pistons as required
5. Carbon in oil control ring groove 5. Remove rings and de-carbon piston
6. Worn valve guides 6. Inspect/replace valve guides as
necessary
7. Piston rings fitted too tightly in
grooves7. Remove rings and check ring end gap
and side clearance. Replace if
necessary
DRENGINE 8.0L 9 - 357
ENGINE 8.0L (Continued)