SECTION 6 – TROUBLESHOOTING (4JB1T MODELS)
1. HARD STARTING
A. STARTER MOTOR INOPERATIVE
B. STARTER MOTOR OPERATES BUT ENGINE DOES NOT TURN OVER
C. ENGINE TURNS OVER BUT DOES NOT START
2. UNSTABLE IDLING
3. INSUFFICIENT POWER
4. EXCESSIVE FUEL CONSUMPTION
5. EXCESSIVE OIL CONSUMPTION
6. OVERHEATING
7. WHITE EXHAUST SMOKE
8. DARK EXHAUST SMOKE
9. OIL PRESSURE DOES NOT RISE
10. ABNORMAL ENGINE NOISE
A. ENGINE KNOCKING
B. SLAPPING NOSIE
11. TURBOCHARGER
A. ENGINE HAS LESS THAN NORMAL POWER
B. BLUE OR BLACK SMOKE
C. EXCESSIVE OIL CONSUMPTION
D. EXCESSIVE TURBOCHARGER NOISE
E. EXCESSIVE ROTATING PART WEAR
Techline
Refer to the following troubleshooting charts to quickly pinpoint and repair engine problems.
1. This Section is divided into ten Sub-Sections.
Refer to the Table of Contents.
2. Each troubleshooting chart has three headings arranged from left to right.
Example:
3. Easily checked areas are presented at the beginning of the troubleshooting chart. Procedures become more
complex as the chart progresses.
4. It is suggested that you work from the beginning of the troubleshooting chart. Do not start from the middle.
5. It is possible that a seemingly apparent engine problem is not related to the engine.
For example, the engine may appear to have insufficient power. This could be caused by dragging brakes or a
slipping clutch instead of an engine malfunction.
Refer to the other troubleshooting charts if required.
6. Optional equipment and variations are included in the troubleshooting charts.
If the vehicle you are servicing is not equipped with a particular option or variation noted in the “Checkpoint”
frame, disregard the frame and move on to the next one.
1503
Fuel line Fuel filter cartridge
clogged or fouled Replace the fuel flter
Fuel line clogged Clean the fuel line
Fuel pump Defective fuel pump Replace the fuel pump
OK
NG
NG
NG
3.INSUFFICIENT POWER
Checkpoint Trouble Cause Countermeasure
1. HARD STARTI NG
A. ST ARTER INOPER ATIVE
Checkpoint Trouble Cause Countermeasure
Battery Loose battery cable terminals
Poor connections due to rusting Clean and/or retighten the
battery cable terminals
Battery discharged or weak Recharge or replace the battery
Fan belt loose or broken Adjust or replace the fan belt
Main fuse Main fuse shorted Replace the main fuse
Starter switch Defective starter switch or
starter relay Replace the starter switch or
the starter relay
Starter motor Defective magnetic switch or
starter relay Repair or replace the magnetic
switch
Defective starter motor Repair or replace the starter
motor
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
B. STARTER MO TOR OPERATES BUT ENGINE DOES NOT TURN OVER
Checkpoint Trouble Cause Countermeasure
Battery Loose battey cable terminals
Poor connections due to rusting Clean and/or retighten the
battery cable terminals
Battery discharged or weak Recharge or replace the battery
Fan belt loose or broken Adjust or replace the fan belt
Starter motor Defective pinion gear Replace the pinion gear
Defective magnetic switch Repair or replace the magnetic
switch
Brush wear
Weak brush spring Replace the brush and/or the
brush spring
Engine Piston, crank bearing seizure,
or other damage Repair or replace the related
parts
OK
OK
NG
NG
NG
NG
NG
NG
NG
C. ENGINE TURNS OVER BUT DOES NOT START
Checkpoint Trouble Cause Countermeasure
FUEL IS NOT BEING DELIVERED TO THE INJECTION PUMP
Engine stop mechanism Defective fuel cut solenoid
value Replace the fuel cut solenoid
valve
NG
Fuel Fuel tank is empty Fill the fuel tank
Fuel piping Clogged or damaged fuel lines
Loose fuel line connections
Repair or replace the fuel lines
Retighten the fuel line
connections
Fuel filter Fuel filter overflow valve does
not close Repair or replace the fuel filter
overflow valve
Clogged fuel filter element Replace the fuel filter element
or the fuel filter cartridge
Fuel system Air in the fuel system Bleed the air from the fuel
system
Fuel feed pump Defective feed pump Repair or replace the feed
pump
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
FUEL IS BEING DELIVERED TO THE INJECTION PUMP
Checkpoint Trouble Cause Countermeasure
Fuel Use of the w rong fuel Use the correct fuel
Water particles in the fuel Change the fuel
Fuel system Air in the injection pump Bleed the air from the fuel
system
Injection nozzle sticking Replace the injection nozzle
Injection nozzle injection
starting pressure too low
Improper spray condition
Adjust or replace the injection
nozzle
Defective fuel injection nozzle
resulting in fuel drippage after
fuel injection Replace the delivery valve
Injection pump plunger worn or
stuck Replace the injection pump
plunger assembly
Continued on the next page
OK
OK
NG
NG
NG
NG
NG
NG
NG
Injection nozzle
Injection pump
OK
Checkpoint Trouble Cause Countermeasure
Injection pump Injection pump drive shaft
seizure or other damage Replace the injection pump
drive shaft
Injection pump governor spring
seizure Replace the injection pump
governor spring
NG
NG
Continued from the previous page
2. UNSTABLE IDLING
Checkpoint Trouble Cause Countermeasure
Idling system Idling improperly adjusted Adjust the idling
Defective fast idling speed
control device Repair or replace the fast idling
speed control device
Fast idling speed control device
Accelerator control system
improperly adjusted Adjust the accelerator control
system
Accelerator control system
Fuel system leakage or
blockage Repair or replace the fuel
system
Fuel system
Air in the fuel system Bleed the air from the fuel
system
Water particles in the fuel
system Change the fuel
Fuel filter Clogged fuel filter element Replace the fuel filter cartridge
the fuel filter cartridge
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Checkpoint Trouble Cause Countermeasure
Fuel feed pump Defective fuel feed pump Replace the fuel feed pump
Injection nozzle sticking Replace the injection nozzleInjection nozzle
Injection nozzle injection
starting pressure too low
Improper spray condition
Adjust or replace the injection
nozzle
Defective delivery valve
resulting in fuel drippage after
fuel injection Replace the delivery valve
Injection pump
Injection timing improperly
adjusted Adjust the injection timing
Insufficient injection v olume Adjust the injection volume
Defective idle spring Replace the idle spring
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Continued from the previous page
OK
Checkpoint Trouble Cause Countermeasure
Injection pump Defective governor lever
operation Repair or replace the governor
lever
Regulator valve improperly
adjusted Adjust or replace the regulator
valve
Broken plunger spring Replace the plunger spring
Worn plunger Replace the plunger assembly
Worn cam disc Replace the cam disc
Valve clearance improperly
adjusted Adjust the valve clearance
Blown out cylinder head gasket
Worn cylinder liner
Piston ring sticking or broken
Improper seating between the
valve and the valve seat
Replace the related parts
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued from the previous page
Valve clearance
Compression pressure
3. INSUFFICIENT POWER
Checkpoint Trouble Cause Countermeasure
Air cleaner Clogged air cleaner element Clean or replace the air cleaner
element
Water particles in the fuel Replace the fuelFuel
Clogged fuel filter element Replace the fuel filter element
or the fuel filter cartridge
Fuel filter
Defective fuel feed pump Repair or replace the fuel feed
pump
Fuel feed pump
Injection nozzle sticking Replace the injection nozzle
Injection nozzle injection
starting pressure too low
Improper spray condition
Adjust or replace the injection
nozzle
Fuel injection pipes Fuel injection pipes damaged or
obstructed Replace the fuel injection pipes
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Injection nozzle
OK
Checkpoint Trouble Cause Countermeasure
Injection pump Defective regulating valve Repair or replace the regulating
valve
Defective delivery valve Replace the delivery valve
Defective timer Repair or replace the timer
Worn cam disk Replace the cam disk
Improper control lever operation Adjust or replace the control
lever
Defective injection timing Adjust the injection timing
Repair or replace the injection
pump timer
Weak governor spring Replace the governor spring
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Continued from the previous page
OK
Checkpoint Trouble Cause Countermeasure
Injection pump Worn plunger Replace the plunger assembly
Worn cam disc Replace the cam disc
Booster compensator pipe
broken or cracked Replace the booster
compensator pipe
Exhaust gas leakage from the
exhaust system
Air leakage from the intake
system
Repair or replace the related
parts
Defective waste gate Repair or replace the waste
gate
Defective turbocharger
assembly Replace the turbocharger
assembly
Blown out cylinder head gasket
Worn cylinder liner
Piston ring sticking or broken
Improper seating between the
valve and the valve seat
Replace the related parts
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Continued from the previous page
Turbocharger
OK
Compression pressure
OK
Checkpoint Trouble Cause Countermeasure
Valve clearance Valve clearance improperly
adjusted Adjust the valve clearance
Valve spring weak or broken Replace the valve spring
Exhaust pipe clogged Clean the exhaust pipe
Open and improperly set
adjusting screw seal Adjust and reseal the adjusting
screw
NG
NG
NG
NG
Continued from the previous page
Exhaust system
OK
Full load adjusting screw seal
OK
Valve spring
OK
OK
4. EXCESSIVE FUEL CONSUMPTION
Checkpoint Trouble Cause Countermeasure
Fuel system Fuel leakage Repair or replace the fuel
system related parts
Clogged air cleaner element Clean or replace the air cleaner
element
Air cleaner
Poorly adjusted idling speed Adjust the idling speed
Idling speed
Injection nozzle injection
starting pressure too low
Improper spray condition
Adjust or replace the injection
nozzle
Injection nozzle
Fuel injection timing improperly
adjusted Adjust the fuel injection timing
Defective delivery valve
resulting in fuel drippage after
fuel injection Replace the delivery valve
Turbocharger Air leakage from the
turbocharger intake side Repair the turbocharger intake
side
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Fuel injection timing
OK
Injection pump
OK
Checkpoint Trouble Cause Countermeasure
Turbocharger Defective turbocharger
assembly Replace the turbocharger
assembly
Valve clearance improperly
adjusted Adjust the valve clearance
Blown out cylinder head gasket
Worn cylinder liner
Piston ring sticking or broken
Improper seating between the
valve and the valve seat
Replace the related parts
Valve spring weak or broken Replace the valve spring
NG
NG
NG
NG
Continued from the previous page
Compression pressure
OK
Valve spring
OK
Valve clearance
OK
5. EXCESSIVE OIL CONSUMPTION
Checkpoint Trouble Cause Countermeasure
Engine oil Engine oil unsuitable
Too much engine oil Replace the engine oil
Correct the engine oil volume
Oil leakage from the oil seal
and/or the gasket Replace the oil seal and/or the
gasket
Oil seal and gasket
Clogged air breather Clean the air breather
Air breather
Worn valve stems and valve
guides Replace the intake and exhaust
valves and the valve guides
Intake and exhaust valves
OK
OK
OK
NG
NG
NG
NG
Techline
6. OVERHEATI NG
Checkpoint Trouble Cause Countermeasure
Cooling water Insufficient cooling water Replenish the cooling water
Oil leakage from the fan
coupling Replace the fan coupling
Fan coupling (if so equipped)
Fan belt loose or cracked
causing slippage Replace the fan belt
Fan belt
Defective radiator cap or
clogged radiator core Replace the radiator cap or
clean the radiator core
Radiator
Defective water pump Repair or replace the water
pump
Defective sealing cap resulting
in water leakage Replace the sealing cap
Thermostat Defective thermostat Replace the thermostat
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Water pump
OK
Cylinder head and cylinder body
sealing cap
OK
Checkpoint Trouble Cause Countermeasure
Cooling system Cooling system clogged by
foreign material Clean the foreign material from
the cooling system
Fuel injection timing improperly
adjusted Adjust the fuel injection timing
NG
NG
Continued from the previous page
Fuel injection timing
OK
OK
7. WHITE EXHAUST SM OKE
Checkpoint Trouble Cause Countermeasure
Fuel Water particles in the fuel Replace the fuel
Delayed fuel injection timing Adjust the fuel injection timingFuel injection timing
Blown out cylinder head gasket
Worn cylinder liner
Piston ring sticking or broken
Improper seating between the
valve and the valve seat
Replace the related parts
Compression pressure
Defective turbocharger Replace the turbocharger
Turbocharger
Defective valve seals
Worn valve stems and valve
guides
Replace the valve seals, the
valve, and the valve guides
OK
OK
OK
NG
NG
NG
NG
NG
Inlet and exhaust valves
Valve seals
OK
8. DARK EXHAUST SMOKE
Checkpoint Trouble Cause Countermeasure
Air cleaner Clogged air cleaner element Clean or replace the air cleaner
element
Injection nozzle injection
starting pressure too low
Improper spray condition
Adjust or replace the injection
nozzle
Injection nozzle
Fuel injection timing improperly
adjusted Adjust the fuel injection timing
Fuel injection timing
Defective delivery valve
resulting in fuel drippage after
fuel injection Replace the delivery valve
Injection pump
Excessive injection volume Adjust the injection volume
OK
OK
OK
NG
NG
NG
NG
NG
Techline
9. OIL PRESSURE DOES NOT RISE
Checkpoint Trouble Cause Countermeasure
Engine oil Improper viscosity engine oil
Insufficient engine oil Replace the engine oil
Correct the engine oil volume
Defective oil pressure gauge or
unit
Defective indicator light
Repair or replace the oil
pressure gauge or unit
Replace the indicator light
Oil pressure gauge or unit
Oil pressure indicator light
Clogged oil filter element Replace the oil filter element or
the oil filter cartridge
Oil filter
Relief valve sticking and/or
weak bypass valve spring Replace the relief valve and/or
the bypass valve spring
Relief valve and bypass valve
Clogged oil pump strainer Clean the oil pump strainer
Worn oil pump related parts Replace the oil pump related
parts
Rocker arm shaft Worn rocker arm bushing Replace the rocker arm
bushing
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Oil pump
OK
Checkpoint Trouble Cause Countermeasure
Camshaft Worn camshaft and camshaft
bearing Replace the camshaft and the
camshaft bearings
Worn crankshaft and bearings Replace the crankshaft and/or
the bearings
NG
NG
Continued from the previous page
Crankshaft and bearings
OK
OK
10. ABNORMAL ENGINE NOISE
A. ENGINE KNOCKING
Checkpoint Trouble Cause Countermeasure
Check to see that the engine has been thoroughly warmed up before beginning the troubleshooting procedure.
2. Gas Leakage Noise
Fuel Fuel unsuitable Replace the fuel
Fuel injection timing improperly
adjusted Adjust the fuel injection timingFuel injection timing
Improper injection nozzle
starting pressure and spray
condition
Adjust or replace the injection
nozzle
Injection nozzle
Blown out head gasket
Broken piston ring Replace the head gasket or the
piston ring
Compression pressure
OK
OK
OK
NG
NG
NG
NG
Loosely connected exhaust
pipes
Broken exhaust pipes
Tighten the exhaust pipe
connections
Replace the exhaust pipes
Injection nozzles and/or glow
plugs Loose injection nozzles and/or
glow plugs
Replace the washers
Tighten the injection nozzles
and/or the glow plugs
OK
NG
NG
Continued on the next page
Exhaust pipes
Checkpoint Trouble Cause Countermeasure
3. Continuous Noise
Exhaust manifold Loosely connected exhaust
manifold and/or glow plugs Tighten the exhaust manifold
connections
Damaged cylinder head gasket Replace the cylinder head
gasket
NG
NG
Continued from the previous page
Cylinder head gasket
OK
OK
Fan belt Loose fan belt Readjust the fan belt tension
Loose cooling fan Retighten the cooling fanCooling fan
Worn or damaged water pump
bearing Replace the water pump
bearing
Water pump bearing
Defective generator or vacuum
pump Repair or replace the generator
or the vacuum pump
Generator or vacuum pump
Valve clearance improperly
adjusted Adjust the valve clearance
OK
OK
OK
NG
NG
NG
NG
NG
Valve clearance
OK
B. SLAPPING NOISE
Checkpoint Trouble Cause Countermeasure
Valve clearance Valve clearance improperly
adjusted Adjust the valve clearance
Damaged rocker arm Replace the rocker armRocker arm
Loose flywheel bolts Retighten the flywheel bolts
Flywheel
Worn or damaged crankshaft
and/or thrust bearings Replace the crankshaft and/or
the thrust bearings
Crankshaft and thrust bearings
Worn or damaged crankshaft
and/or connecting rod bearings Replace the crankshaft and/or
the connecting rod bearings
Worn or damaged connecting
rod bushing and piston pin Replace the connecting rod
bushing and/or the piston pin
Piston and cylinder liner Worn or damaged piston and
cylinder liner
Foreign material in the cylinder
Replace the piston and the
cylinder liner
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Crankshaft and connecting rod
bearings
OK
Connecting rod bushing and
piston pin
OK
11. TURBOCHARGER
A. ENGINE HAS LESS THAN NORMAL PO W ER
Checkpoint Trouble Cause Countermeasure
Air cleaner Restricted Clean or replace
Restricted Clean or replaceIntake pipe and hose
Loose (Leaking) Repair
Compressor/intake manifold
Loose (Leaking) Repair
Exhaust manifold/turbine inlet
Restricted Clean or replace
Restricted Clean or replace
Boost compensator
(Injection pump) Defective Repair or replace
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Exhaust piping and silencers
OK
Air breather
OK
Checkpoint Trouble Cause Countermeasure
Compressor wheel Impact damage Replace
Impact damage Replace
Carbon build-up Replace
Dragging or seized Replace
NG
NG
NG
NG
Continued from the previous page
Rotating assembly
OK
Turbine wheel
OK
OK
B. BLUE OR BLACK SMOKE
Checkpoint Trouble Cause Countermeasure
Air cleaner or intercooler Restricted Clean, repair, or replace
Leakage ReplaceTurbocharger oil seal
Restricted Repair or replace
Turbocharger oil drain pipe
Defective Repair or replace
PCV system
Excessive pressure Repair
Impact damage Replace
Turbine wheel Impact damage Replace
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Crankcase
OK
Compressor wheel
OK
Checkpoint Trouble Cause Countermeasure
Center housing oil drain
passage Restricted Clean or replace
NG
Continued from the previous page
OK
C. EXCESSIVE O IL CONSUMPTIO N
Checkpoint Trouble Cause Countermeasure
P.C.V system Defective Repair or replace
Excessive pressure RepairCrankcase
Leakage Replace
Turbocharger oil seal
Restricted Clean or replace
Turbocharger oil drain pipe
Impact damaged Replace the turbine housing
Impact damage Replace the compressor
housing and rotating assembly
Oil Pressure Excessive Repair
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Turbine wheel
OK
Compressor wheel
OK
Checkpoint Trouble Cause Countermeasure
Center housing oil drain
passage Restricted Clean or replace
NG
Continued from the previous page
OK
D. EXCESSIVE TURBOCHARGER NOISE
Checkpoint Trouble Cause Countermeasure
Intake and exhaust system
joints Loose Repair
Damaged Repair
Intake and exhaust system
gaskets
Rough rotation Replace
Turbocharger rotating parts
Rubbing against housing Repair or replace
Compressor wheel
Damaged Replace
Rubbing against housing Repair or replace
Damaged Replace
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG
Continued on the next page
Turbine wheel
OK
Checkpoint Trouble Cause Countermeasure
Carbon deposits Clean or replace
Too low Correct
Contaminated Replace oil
Restricted Repair or replace
Carbon deposits Clean
Dirty Clean
Worn Replace
NG
NG
NG
NG
NG
NG
NG
Continued from the previous page
Oil Level
OK
Turbine shaft bearings
OK
Turbocharger oil feed pipe
OK
Turbine housing
OK
Compressor housing
OK
E. EXCESSIVE RO TATING PART WEAR
Checkpoint Trouble Cause Countermeasure
Engine oil Contaminated Change
Wrong grade or type Change
Restricted Clean or replace
Turbocharger oil feed pipe
Defective Replace
Turbocharger oil seal
Restricted Clean or replace
Oil sludge and coking Replace
Inadequate oil supply Correct
OK
OK
NG
NG
NG
NG
NG
NG
NG
Turbine shaft
OK
Center housing oil drain
passage
OK
Engine lubrication system
OK