
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 - 226 ENGINE - 5.9LDR
ENGINE - 5.9L (Continued)

The relief valve spring has a free length of approx-
imately 49.5 mm (1.95 inches). The spring should
test between 19.5 and 20.5 pounds when compressed
to 34 mm (1-11/32 inches). Replace spring that fails
to meet these specifications (Fig. 66).
If oil pressure was low and pump is within specifi-
cations, inspect for worn engine bearings or other
reasons for oil pressure loss.
ASSEMBLY
(1) Install pump rotors and shaft, using new parts
as required.
(2) Position the oil pump cover onto the pump
body. Tighten cover bolts to 11 N´m (95 in. lbs.)
torque.
(3) Install the relief valve and spring. Insert the
cotter pin.
(4) Tap on a new retainer cap.
(5) Prime oil pump before installation by filling
rotor cavity with engine oil.
INSTALLATION
(1) Install oil pump. During installation slowly
rotate pump body to ensure driveshaft-to-pump rotor
shaft engagement.
(2) Hold the oil pump base flush against mating
surface on No.5 main bearing cap. Finger tighten
pump attaching bolts. Tighten attaching bolts to 41
N´m (30 ft. lbs.) torque.
(3) Install the oil pan (Refer to 9 - ENGINE/LU-
BRICATION/OIL PAN - INSTALLATION).
INTAKE MANIFOLD
DESCRIPTION
The aluminum intake manifold (Fig. 67) is a single
plane design with equal length runners and uses a
separate plenum, therefore the manifold does have a
plenum gasket. It also uses separate flange gaskets
and front and rear cross-over gaskets. Extreme care
must be used when sealing the gaskets to ensure
that excess sealant does not enter the intake runners
causing a restriction. Whenever the intake manifold
is removed inspect the plenum pan for evidence of
excess oil buildup, this condition indicates that the
plenum pan gasket is leaking.
OPERATION
The intake manifold, meters and delivers air to the
combustion chambers allowing the fuel delivered by
the fuel injectors to ignite, thus producing power.
DIAGNOSIS AND TESTINGÐINTAKE
MANIFOLD LEAKAGE
An intake manifold air leak is characterized by
lower than normal manifold vacuum. Also, one or
more cylinders may not be functioning.
Fig. 66 Proper Installation of Retainer Cap
1 - RETAINER CAP
2 - CHAMFER
3 - COTTER KEY
Fig. 67 Intake Manifold and Throttle BodyÐV-8 Gas
Engines Typical
1 - FUEL RAIL ASSEMBLY
2 - FUEL RAIL MOUNTING BOLTS
3 - FUEL RAIL CONNECTING HOSES
9 - 274 ENGINE - 5.9LDR
OIL PUMP (Continued)

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTINGÐENGINE DIAGNOSIS - MECHANICAL
CONDITION POSSIBLE CAUSES CORRECTION
LUBRICATING OIL
PRESSURE LOW1. Low oil level. 1. (a) Check and fill with clean engine oil.
(b) Check for a severe external oil leak that
could reduce the pressure.
2. Oil viscosity thin, diluted or wrong
specification.2. (a) Verify the correct engine oil is being
used. (Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
DESCRIPTION).
2. (b) Look for reduced viscosity from fuel
dilution.
3. Improperly operating pressure
switch/gauge.3. Verify the pressure switch is functioning
correctly. If not, replace switch/gauge.
4. Relief valve stuck open. 4. Check/replace valve.
6. If cooler was replaced, shipping
plugs may have been left in cooler6. Check/remove shipping plugs.
7. Worn oil pump. 7. Check and replace oil pump.
8. Suction tube loose or seal leaking. 8. Check and replace seal.
9. Loose main bearing cap. 9. Check and install new bearing. Tighten
cap to proper torque.
10. Worn bearings or wrong bearings
installed.10. Inspect and replace connecting rod or
main bearings. Check and replace directed
piston cooling nozzles.
11. Directed piston cooling nozzles
under piston, bad fit into main
carrier.11. Check directed piston cooling nozzles
position.
12. Loose oil rifle plug with saddle-jet
style nozzles12.Tighten oil rifle plug.
13. Loose directed piston cooling
nozzle.13. Tighten directed piston cooling nozzle.
14. Both J-jet and saddle jet style
cooling nozzle installed.14. Install correct style jet.
LUBRICATING OIL
PRESSURE TOO HIGH1. Pressure switch/gauge not
operating properly.1. Verify pressure switch is functioning
correctly. If not, replace switch/gauge.
2. Engine running too cold. 2. Refer to Coolant Temperature Below
Normal (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
3. Oil viscosity too thick. 3. Make sure the correct oil is being used.
(Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
DESCRIPTION).
4. Oil pressure relief valve stuck
closed or binding4. Check and replace valve.
DRENGINE 5.9L DIESEL 9 - 283
ENGINE 5.9L DIESEL (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
LUBRICATING OIL LOSS 1. External leaks. 1. Visually inspect for oil leaks. Repair as
required.
2. Crankcase being overfilled. 2. Verify that the correct dipstick is being
used.
3. Incorrect oil specification or
viscosity.3. (a) Make sure the correct oil is being
used (Refer to LUBRICATION &
MAINTENANCE/FLUID TYPES -
DESCRIPTION).
(b) Look for reduced viscosity from dilution
with fuel.
(c) Review/reduce oil change intervals.
4. Oil cooler leak 4. Check and replace the oil cooler.
5. High blow-by forcing oil out the
breather.5. Check the breather tube area for signs of
oil loss. Perform the required repairs.
6. Turbocharger leaking oil to the air
intake.6. Inspect the air ducts for evidence of oil
transfer. Repair as required.
COMPRESSION KNOCKS 1. Air in the fuel system. 1. Identify location of air leak and repair. Do
not bleed high pressure fuel system.
2. Poor quality fuel or water/gasoline
contaminated fuel.2. Verify by operating from a temporary
tank with good fuel. Clean and flush the
fuel tank. Replace fuel/water separator filter.
3. Engine overloaded. 3. Verify the engine load rating is not being
exceeded.
4. Improperly operating injectors. 5. Check and replace misfiring/inoperative
injectors.
EXCESSIVE VIBRATION 1. Loose or broken engine mounts. 1. Replace engine mounts.
2. Damaged fan or improperly
operating accessories.2. Check and replace the vibrating
components.
3. Improperly operating vibration
damper3. Inspect/replace vibration damper.
4. Improperly operating electronically
controlled viscous fan drive.4. Inspect/replace fan drive.
5. Worn or damaged generator
bearing.5. Check/replace generator.
6. Flywheel housing misaligned. 6. Check/correct flywheel alignment.
7. Loose or broken power
component.7. Inspect the crankshaft and rods for
damage that causes an unbalance
condition. Repair/replace as required.
8. Worn or unbalanced driveline
components.8. Check/repair driveline components.
EXCESSIVE ENGINE
NOISES1. Drive belt squeal, insufficient
tension or abnormally high loading.1. Check the automatic tensioner and
inspect the drive belt. Make sure water
pump, tensioner pulley, fan hub, generator
and power steering pump turn freely.
2. Intake air or exhaust leaks. 2. Refer to Excessive Exhaust Smoke
(Refer to 9 - ENGINE - DIAGNOSIS AND
TESTING).
9 - 284 ENGINE 5.9L DIESELDR
ENGINE 5.9L DIESEL (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
3. Excessive valve lash. 3. Adjust valves. Make sure the push rods
are not bent and rocker arms, adjusting
screws, crossheads, are not severely worn.
Replace bent or severely worn components.
4. Turbocharger noise. 4. Check turbocharger impeller and turbine
wheel for housing contact. Repair/replace
as required.
5. Gear train noise. 5. Visually inspect and measure gear
backlash. Replace gears as required.
6. Power function knock. 6. Check/replace rod and main bearings.
DIAGNOSIS AND TESTINGÐSMOKE
DIAGNOSIS CHARTS
The following charts include possible causes and
corrections forexcess or abnormalexhaust smoke.Small amounts of exhaust smoke (at certain times)
are to be considered normal for a diesel powered
engine.
EXCESSIVE BLACK SMOKE
POSSIBLE CAUSE CORRECTION
Air filter dirty or plugged. Check Filter MinderTat air filter (Refer to 9 - ENGINE/
AIR INTAKE SYSTEM/AIR CLEANER ELEMENT -
REMOVAL).
Air intake system restricted. Check entire air intake system including all hoses and
tubes for restrictions, collapsed parts or damage.
Repair/replace as necessary.
Air Leak in Intake System. Check entire air intake system including all hoses and
tubes for cracks, loose clamps and/or holes in rubber
ducts. Also check intake manifold for loose mounting
hardware.
Diagnostic Trouble Codes (DTC's) active or multiple,
intermittent DTC's.Refer to Powertrain Diagnostic Procedures Information.
Engine Control Module (ECM) not calibrated or ECM
has incorrect calibration.Refer to Powertrain Diagnostic Procedures Information.
Exhaust system restriction is above specifications. Check exhaust pipes for damage/restrictions. Repair as
necessary.
Fuel grade is not correct or fuel quality is poor. Temporarily change fuel brands and note condition.
Change brand if necessary.
Fuel injection pump malfunctioning. A DTC may have been set. If so, refer to Powertrain
Diagnostic Procedures Information.
Fuel injector malfunctioning. A DTC may have been set. Perform9Cylinder Cutout
Test9using DRB scan tool to isolate individual
cylinders. Also refer to Powertrain Diagnostic
Procedures Information and, to (Refer to 14 - FUEL
SYSTEM/FUEL INJECTION/FUEL INJECTOR -
DIAGNOSIS AND TESTING).
Fuel return system restricted. Check fuel return lines for restriction (Refer to 14 -
FUEL SYSTEM/FUEL DELIVERY - DIAGNOSIS AND
TESTING).
Intake manifold restricted. Remove restriction.
DRENGINE 5.9L DIESEL 9 - 285
ENGINE 5.9L DIESEL (Continued)

EXCESSIVE BLACK SMOKE
POSSIBLE CAUSE CORRECTION
Manifold Air Pressure (Boost) Sensor or sensor circuit
malfunctioning.A DTC should have been set. Refer to Powertrain
Diagnostic Procedures Information.
Raw fuel in intake manifold. Fuel injectors leaking on engine shutdown. Do Fuel
Injector Test (Refer to 14 - FUEL SYSTEM/FUEL
INJECTION/FUEL INJECTOR - DIAGNOSIS AND
TESTING).
Turbocharger air intake restriction. Remove restriction.
Turbocharger damaged. (Refer to 11 - EXHAUST SYSTEM/TURBOCHARGER
SYSTEM/TURBOCHARGER - INSPECTION).
Turbocharger has excess build up on compressor
wheel and/or diffuser vanes.(Refer to 11 - EXHAUST SYSTEM/TURBOCHARGER
SYSTEM/TURBOCHARGER - CLEANING).
Turbocharger wheel clearance out of specification. (Refer to 11 - EXHAUST SYSTEM/TURBOCHARGER
SYSTEM/TURBOCHARGER - INSPECTION).
EXCESSIVE WHITE SMOKE
POSSIBLE CAUSE CORRECTION
Air in fuel supply: Possible leak in fuel supply side
(between transfer pump and fuel tank module).(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY/FUEL
TRANSFER PUMP - DIAGNOSIS AND TESTING).
Coolant leaking into combustion chamber. Do pressure test of cooling system (Refer to 7 -
COOLING - DIAGNOSIS AND TESTING).
Diagnostic Trouble Codes (DTC's) active or multiple,
intermittent DTC's.Refer to Powertrain Diagnostic Procedures Information.
In very cold ambient temperatures, engine block heater
is malfunctioning (if equipped).(Refer to 7 - COOLING/ENGINE/ENGINE BLOCK
HEATER - REMOVAL).
Engine coolant temperature sensor malfunctioning. A DTC should have been set. Refer to Powertrain
Diagnostic Procedures Information. Also check
thermostat operation (Refer to 7 - COOLING/ENGINE/
ENGINE COOLANT THERMOSTAT - DIAGNOSIS AND
TESTING).
Engine Control Module (ECM) not calibrated or has
incorrect calibration.A DTC should have been set. Refer to Powertrain
Diagnostic Procedures Information.
Fuel filter plugged. Refer to Powertrain Diagnostic Manual for fuel system
testing.
Fuel grade not correct or fuel quality is poor. Temporarily change fuel brands and note condition.
Change brand if necessary.
Fuel heater element or fuel heater temperature sensor
malfunctioning. This will cause wax type build-up in fuel
filter.Refer to Fuel Heater Testing (Refer to 14 - FUEL
SYSTEM/FUEL DELIVERY/FUEL HEATER -
DIAGNOSIS AND TESTING).
Fuel injector malfunctioning. A DTC should have been set. Perform9Cylinder cutout
Test9using DRB scan tool to isolate individual
cylinders. Also refer to Powertrain Diagnostic
Procedures Information and, (Refer to 14 - FUEL
SYSTEM/FUEL INJECTION/FUEL INJECTOR -
DIAGNOSIS AND TESTING).
Fuel injector hold-downs loose. Torque to specifications.
9 - 286 ENGINE 5.9L DIESELDR
ENGINE 5.9L DIESEL (Continued)

EXCESSIVE WHITE SMOKE
POSSIBLE CAUSE CORRECTION
Fuel injector protrusion not correct. Check washer (shim) at bottom of fuel injector for
correct thickness. (Refer to 14 - FUEL SYSTEM/FUEL
INJECTION/FUEL INJECTOR - INSTALLATION)
Fuel injection pump malfunctioning. A DTC should have been set. Refer to Powertrain
Diagnostic Procedures Information.
Fuel supply side restriction to transfer pump. Refer to Powertrain Diagnostic Manual for fuel system
testing.
Fuel transfer (lift) pump malfunctioning. A DTC may have been set. Refer to Powertrain
Diagnostic Procedures Information.
Intake/Exhaust valve adjustments not correct (too tight). (Refer to 9 - ENGINE/CYLINDER HEAD/INTAKE/
EXHAUST VALVES & SEATS - STANDARD
PROCEDURE).
Intake manifold air temperature sensor malfunctioning. A DTC should have been set. Refer to Powertrain
Diagnostic Procedures Information.
Intake manifold heater circuit not functioning correctly in
cold weather.A DTC should have been set. Refer to Powertrain
Diagnostic Procedures Information. Also check heater
elements for correct operation.
Intake manifold heater elements not functioning
correctly in cold weather.A DTC should have been set if heater elements are
malfunctioning. Refer to Powertrain Diagnostic
Procedures Information.
Internal engine damage (scuffed cylinder). Analyze engine oil and inspect oil filter to locate area of
probable damage.
Restriction in fuel supply side of fuel system. Refer to Powertrain Diagnostic Manual for fuel system
testing.
EXCESSIVE BLUE SMOKE
POSSIBLE CAUSE CORRECTION
Dirty air cleaner or restricted turbocharger intake duct. Check Filter MinderTat air filter housing. (Refer to 9 -
ENGINE/AIR INTAKE SYSTEM/AIR CLEANER
ELEMENT - REMOVAL).
Air leak in boost system between turbocharger
compressor outlet and intake manifold.Service air charge system..
Obstruction in exhaust manifold. Remove exhaust manifold and inspect for blockage
(Refer to 9 - ENGINE/MANIFOLDS/EXHAUST
MANIFOLD - REMOVAL).
Restricted turbocharger drain tube. Remove turbocharger drain tube and remove
obstruction.
Crankcase ventilation system plugged. Inspect crankcase ventilation system for function
Valve seals are worn, brittle, or improperly installed. Replace valve stem oil seals (Refer to 9 - ENGINE/
CYLINDER HEAD/INTAKE/EXHAUST VALVES &
SEATS - REMOVAL).
Valve stems and/or guides are worn. Remove valves and inspect valves and guides. (Refer
to 9 - ENGINE/CYLINDER HEAD/INTAKE/EXHAUST
VALVES & SEATS - STANDARD PROCEDURE).
Broken or Improperly installed piston rings. Tear down engine and inspect piston rings.
DRENGINE 5.9L DIESEL 9 - 287
ENGINE 5.9L DIESEL (Continued)

EXCESSIVE BLUE SMOKE
POSSIBLE CAUSE CORRECTION
Excessive piston ring end gap. Remove pistons and measure piston ring end gap
(Refer to 9 - ENGINE/ENGINE BLOCK/PISTON RINGS
- STANDARD PROCEDURE).
Excessive cylinder bore wear and taper. Remove pistons and measure cylinder bore wear and
taper (Refer to 9 - ENGINE/ENGINE BLOCK -
STANDARD PROCEDURE).
Cylinder damage. Remove pistons and inspect cylinder bore for cracks or
porosity. Repair with cylinder liner if necessary. (Refer
to 9 - ENGINE/ENGINE BLOCK - STANDARD
PROCEDURE).
Piston damage. Remove pistons and inspect for cracks, holes. Measure
piston for out-of-round and taper (Refer to 9 -
ENGINE/ENGINE BLOCK/PISTON & CONNECTING
ROD - INSPECTION).
Turbocharger failure. (Refer to 11 - EXHAUST SYSTEM/TURBOCHARGER
SYSTEM/TURBOCHARGER - INSPECTION).
DIAGNOSIS AND TESTINGÐCYLINDER
COMPRESSION/LEAKAGE TESTS
CYLINDER COMPRESSION PRESSURE
The results of a cylinder compression pressure test
can be utilized to diagnose several engine malfunc-
tions.
Ensure batteries are completely charged and the
engine starter motor is in good operating condition.
Otherwise, the indicated compression pressures may
not be valid for diagnostic purposes.
(1) Disconnect the fuel inlet line to the fuel trans-
fer pump. Plug the fuel line from the fuel tank.
(2) Start the engine and idle until the engine stalls
(runs out of fuel).
(3) Disconnect all three injector wire harness con-
nectors at the rocker housing.
(4) Remove the breather cover and cylinder head
cover.
(5) Remove the high pressure fuel line between the
cylinder head and fuel rail for the cylinder to be
tested.
(6) Remove the exhaust rocker lever.
(7) Use Tool 9010 to remove the injector and cop-
per sealing washer.
(8) Install the exhaust rocker lever and torque to
43 N´m (32 ft. lbs.).
(9) Cover the remaining rocker levers with clean
shop towels to prevent any oil splatter under the
hood.
(10) Place a rag over the compression test tool fit-
ting. Crank the engine for 2±3 seconds to purge any
fuel that may have drained into the cylinder when
the injector was removed.(11) Connect the compression test gauge.
(12) Crank the engine for 5 seconds and record the
pressure reading. Repeat this step three times and
calculate the average of the three readings.
(13) Combustion pressure leakage can be checked
if cylinder pressure is below the specification. Per-
form the leakage test procedure on each cylinder
according to the tester manufacturer instructions.
(14) Upon completion of the test check an erase
any engine related fault codes.
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
jacket.
²Any causes for combustion/compression pressure
loss
(1) Start and operate the engine until it attains
normal operating temperature.
(2) Remove the breather cover and cylinder head
cover.
(3) Disconnect all three injector wire harness con-
nectors at the rocker housing.
(4) Bring the cylinder to be tested to TDC.
(5) Remove the high pressure fuel line between the
cylinder head and the fuel rail for the cylinder to be
tested.
(6) Install capping Tool 9011 onto the rail.
(7) Remove the high pressure connector nut and
high pressure connector with Tool 9015.
(8) Remove the exhaust and intake rocker lever.
9 - 288 ENGINE 5.9L DIESELDR
ENGINE 5.9L DIESEL (Continued)