Isuzu 4JB1 Operating and installation instructions

SERVICE INFORMATION 00 – 3
1.HARD STARTING
1. STARTER INOPERATIVE
Checkpoint Possible cause Correction
Loose battery cable terminal poor
connections due to rusting Clean and/or retighten the battery cable terminal
Battery discharged or weak Recharge or replace the battery
Battery
Fan belt loose or broken Adjust or replace the fan belt
Fusible link Fusible link shorted Replace the fusible link
Starter switch Defective starter switch or starter relay Replace the starter switch or the
Starter relay
Defective magnetic switch or starter relay Repair or replace the magnetic switch Starter motor
Defective starter motor Repair or replace the starter motor
2. STARTER MOTOR OPERATES BUT ENGINE DOES NOT TURN OVER
Loose battery cable terminal Clean and/or retighten the battery
cable terminal
Poor connections due to rusting Recharge or replace the battery
Battery discharged or weak Recharge or replace the battery
Battery
Fan belt loose or broken Adjust or replace the fan belt
Defective pinion gear Replace the pinion gear
Defective magnetic switch Repair or replace the magnetic switch
Starter
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

00 – 4 SERVICE INFORMATION
3. ENGINE TURNS OVER BUT DOES NOT START
Checkpoint Possible cause Correction
Engine stop
mechanism Defective fuel cut solenoid valve Replace the fuel cut solenoid valve
FUEL IS NOT BEING DELIVERED TO THE INJECTION PUMP
Fuel Fuel tank is empty Fill the fuel tank
Fuel piping Clogged or damaged fuel lines. Loose fuel
line connection Repair or replace the fuel lines Retighten the fuel line connection
Fuel filter overflow valve does not close Repair or replace the fuel filter
overflow valve
Fuel filter
Clogged fuel filter element Replace the fuel filter element or the
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
FUEL IS BEING DELIVERED TO THE INJECTION PUMP
Use of the wrong fuel Use the correct fuel
Water particles in the fuel Change the fuel
Fuel
Fuel system Air in the injection pump Bleed the air from the fuel system
Injection nozzle sticking Injection nozzle
Injection nozzle injection starting pressure
too low
Improper spray condition
Adjust or replace the injection nozzle
Defective fuel injection nozzle resulting in the
fuel drippage after fuel injection Replace the delivery valve
Defective injection pump control rack
operation Repair or replace the injection pump control rack
Injection pump plunger worn or stuck Replace the injection pump plunger
assembly
Injection pump drive shaft seizure or other
damage Replace the injection drive shaft
Injection pump
Injection pump governor spring seizure Replace the injection pump governor
spring

SERVICE INFORMATION 00 – 5
4. QUICK-ON START SYSTEM
PREPARATION
1 Disconnect the thermoswitch connector.
2. Determine whether or not the glow plugs are receiving power.
a) Make sure that the starter switch is “OFF”.
b) Connect a voltmeter between one of the glow plugs and the cylinder wall.
c) Move the starter switch to the “ON” position.
The voltmeter needle will show the souse voltage (12V) if the glow plugs are receiving power.
If the voltmeter needle does not move, the glow plugs are not receiving power.
3. Perform the troubleshooting procedure.
GLOW PLUGS ARE RECEIVING POWER
Checkpoint Possible cause Correction
Glow plug indicator
light does not turn on Defective indicator light bulb Replace the indicator light bulb
Quick-on start timer Defective quick-on start timer Replace the quick-on start timer
Glow plug indicator
light turns on the 0.3
seconds
Defective quick-on start timer Replace the quick-on start timer
Return the starter switch to the “ON” position
from the “START” position after the engine
starts if the glow plug relay remains on less
than 14 seconds, the quick-on start timer is
defective
Replace the quick-on start timer
Glow plug indicator
light turns on for 3.5
seconds
Move the starter switch from the “OFF”
position to the “ON” position if the glow plug
relay remains on less than 14 seconds, the
quick-on start timer is defective
Replace the quick-on start timer
Thermoswitch Defective thermoswitch Replace the thermoswitch
Glow plug continuity No glow plug continuity Replace the glow plugs
GLOW PLUGS ARE NOT RECEIVING POWER
Glow plug indicator
light does not turn on Broken indicator light fuse Replace the fuse
Quick-on start timer Defective quick-on start timer Replace the quick-on start timer

00 – 6 SERVICE INFORMATION
GLOW PLUGS ARE NOT RECEIVING POWER (Cont’d)
Checkpoint Possible cause Correction
Defective glow plug relay
The glow plug relay does not turn on after the
starter switch is moved from the “OFF”
position to the “ON” position
Replace the glow plug relay
Defective quick-on start timer Replace the quick-on start timer
Defective glow plug relay wiring harness Repair or replace the wiring harness
Glow plug indicator
light turns on for 3.5
seconds
Defective fusible link or wiring harness
The glow plug relay turns on when the starter
switch is moved from the “OFF” position to
the “ON” position
Replace the fusible link or the wiring
harness
2. UNSTABLE IDLING
Checkpoint Possible cause Correction
Idling system Idling improperly adjusted Adjust the idling
Fast idling speed Defective fast idling speed control device Repair or replace the fast idling speed
control device
Accelerator control
system Accelerator control system improperly adjusted Adjust the accelerator control system
Fuel system leakage or blockage Repair or replace the fuel system
Air in the fuel system Bleed the air from the fuel system
Fuel system
Water particles in the fuel system Change the fuel
Fuel filter Clogged fuel filter element Replace the fuel filter element or the
fuel filter cartridge
Fuel feed pump Defective fuel feed pump Repair or replace the fuel feed pump
Injection nozzle sticking Replace the injection nozzle Injection nozzle
Injection nozzle injection starting pressure
too low
Improper spray condition
Adjust or replace the injection nozzle
Injection pump Defective delivery valve resulting in fuel
drippage after fuel injection Replace the delivery valve

SERVICE INFORMATION 00 – 7
Checkpoint Possible cause Correction
Injection timing improperly adjusted Adjust the injection timing
Insufficient injection volume Adjust the injection volume
Defective idle spring Replace the idle spring
Defective governor lever operation Repair or replace the governor lever
Regulator valve improperly adjustment Adjust or replace the regulator valve
Broken plunger spring Replace the plunger spring
Worn plunger Replace the plunger assembly
Injection pump
(Cont’d)
Worn cam disc Replace the cam disc
Valve clearance Valve clearance improperly adjusted Adjust the valve clearance
Compression pressure Blown out cylinder head gasket. Worn
cylinder liner.
Piston ring sticking
Replace the related parts
3. INSUFFICIENT POWER
Checkpoint Possible cause Correction
Air cleaner Clogged air cleaner element Clean or replace the air cleaner
element
Fuel Water particle in the fuel Replace fuel
Fuel filter Clogged fuel filter element Replace the fuel filter element or the
fuel filter cartridge
Fuel feed pump Defective fuel feed pump Repair or replace the fuel feed pump
Injection nozzle sticking Replace the injection nozzle 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

00 – 8 SERVICE INFORMATION
Checkpoint Possible cause Correction
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 disc Replace the cam disc
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
Injection pump
Worn plunger Replace the plunger assembly
Compression pressure Blown out cylinder head gasket. Worn
cylinder liner.
Piston ring sticking
Replace the related parts
Valve clearance Valve clearance improperly adjusted Adjust the valve clearance
Valve spring Valve spring weak or broken Replace the valve spring
Exhaust system Exhaust pipe clogged Clean the exhaust pipe
Full load adjusting
screw seal Open and improperly set adjusting screw seal Adjust and reseal the adjusting screw

SERVICE INFORMATION 00 – 9
4. EXCESSIVE FUEL CONSUMPTION
Checkpoint Possible cause Correction
Fuel system Fuel leakage Repair or replace the fuel system
related parts
Air cleaner Clogged air cleaner element Clean or replace the air cleaner
element
Idling speed Poorly adjusted idling speed Adjust the idling speed
Injection nozzle Injection nozzle injection starting pressure
too low
Improper spray condition
Adjust or replace the injection nozzle
Fuel injection timing Fuel injection timing improperly Adjust the fuel injection timing
Injection pump Defective Delivery valve resulting is fuel
drippage after fuel injection Replace the delivery valve
Valve clearance Valve clearance improperly adjusted Adjust the valve clearance
Compression pressure Blown out cylinder head gasket. Worn
cylinder liner.
Piston ring sticking
Replace the related parts
Valve spring Valve spring weak or broken Replace the valve spring
5. EXCESSIVE OIL CONSUMPTION
Checkpoint Possible cause Correction
Engine oil Engine oil unsuitable
Too much engine oil Replace the engine oil Correct the engine oil level
Oil seal and gasket Oil leakage from the oil seal and/or the
gasket Replace the oil seal and/or the gasket
Air breather Clogged air breather Clean the air breather
Intake and exhaust
valve Worn valve stems and valve guides Replace the intake and exhaust valves and the valve guides

00 – 10 SERVICE INFORMATION
6. OVERHEATING
Checkpoint Possible cause Correction
Cooling water Insufficient cooling water Replenish the cooling water
Fan clutch Oil leakage from the fan clutch Replace the fan clutch
Fan belt Fan belt loose or cracked causing slippage Replace the fan belt
Radiator Defective radiator cap or clogged radiator
core Replace the radiator cap or clean the radiator core
Water pump Defective water pump Repair or replace the water pump
Cylinder head and
cylinder body sealing
cap
Defective sealing cap resulting in water
leakage Replace the sealing cap
Thermostat Defective thermostat Replace the thermostat
Cooling system Cooling system clogged by foreign material Clean the foreign material from the
cooling system
Fuel injection timing Fuel injection timing improperly adjusted Adjust the fuel injection timing
7. WHITE EXHAUST SMOKE
Checkpoint Possible cause Correction
Cooling water Insufficient cooling water Replace the cooling water
Fuel Water particles in the fuel Replace the fuel
Fuel injection timing Delayed fuel injection timing Adjust the fuel injection timing
Compression pressure Blown out cylinder head gasket. Worn
cylinder liner.
Piston ring sticking
Replace the related parts
Inlet and exhaust valve
Valves seals Defective valve seals. Worn valves stems and valve guides Replace the valve seals, the valves, and the valve guides

SERVICE INFORMATION 00 – 11
8. DARK EXHAUST SMOKE
Checkpoint Possible cause Correction
Air cleaner Clogged air cleaner element Clean or replace the air cleaner
element
Injection nozzle Injection nozzle injection starting pressure
too low
Improper spray condition
Adjust or replace the injection nozzle
Fuel injection timing Fuel injection timing improperly adjusted Adjust the 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
9. OIL PRESSURE DOES NOT RISE
Checkpoint Possible cause Correction
Engine oil Improper viscosity engine oil.
Insufficient engine oil Replace the engine oil Correct the engine oil volume
Oil pressure gauge or
unit
Oil pressure indicator
light
Defective oil pressure gauge or unit
Defective indicator light
Repair or replace the oil pressure
gauge or unit
Replace the indicator light
Oil filter Clogged oil filter element Replace the oil filter element or the oil
filter cartridge
Relief valve and by-
pass valve Relief valve sticking and/or weak by-pass valve spring Replace the relief valve and/or the by- pass valve spring
Clogged oil pump strainer Clean the oil pump strainer Oil pump
Worn oil pump related parts Replace the oil pump related parts
Rocker arm shaft Worn rocker arm bushing Replace the rocker arm bushing
Camshaft Worn camshaft and camshaft bearing Replace the camshaft and the
camshaft bearing
Crankshaft and
bearings Worn crankshaft and bearings Replace the crankshaft and/or the bearings

00 – 12 SERVICE INFORMATION
10. ABNORMAL ENGINE NOISE
1. ENGINE KNOCKING
Check to see that the engine has been thoroughly warmed up before beginning the troubleshooting procedure.
Checkpoint Possible cause Correction
Fuel Fuel unsuitable Replace the fuel
Fuel injection timing Fuel injection timing improperly adjusted Adjust the fuel injection timing
Injection nozzle Improper injection nozzle starting pressure
and spray condition Adjust or replace the injection nozzle
Compression pressure Blown out head gasket
Broken piston ring
Replace the head gasket or the piston
ring
2. GAS LEAKAGE NOISE
Exhaust pipes 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
Exhaust manifold Loosely connected exhaust manifold and/or
glow plugs Tighten the exhaust manifold connections
Cylinder head gasket Damaged cylinder head gasket Replace the cylinder head gasket
3. CONTINUOUS NOISE
Fan belt Loose fan belt Readjust the fan belt tension
Cooling fan Loose cooling fan Retighten the cooling fan
Water pump bearing Worn or damaged water pump bearing Replace the water pump bearing
Generator or vacuum
pump Defective generator or vacuum pump Repair or replace the generator or the vacuum pump
Valve clearance Clearance improperly adjust Adjust the valve clearances

SERVICE INFORMATION 00 – 13
4. SLAPPING NOISE
Checkpoint Possible cause Correction
Valve clearance Valve clearance improperly adjusted Adjust the valve clearance
Rocker arm Damaged rocker arm Replace the rocker arm
Flywheel Loose flywheel bolts Retighten the flywheel bolts
Crankshaft and thrust
bearings Worn or damaged crankshaft and/or thrust bearings Replace the crankshaft and/or the thrust bearings
Crankshaft and
connecting rod
bearings
Worn or damaged crankshaft and/or
connecting rod bearings Replace the crankshaft and/or the connecting rod bearings
Connecting rod
bushing and piston pin 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. Replace the piston and the cylinder liner.

00 – 14 SERVICE INFORMATION
11. ENGINE COOLING TROUBLE
Checkpoint Possible cause Correction
Low coolant level Replenish
Thermo unit faulty Replace
Faulty thermostat Replace
Faulty coolant unit Repair or replace
Clogged radiator Clean or replace
Faulty radiator cap Replace
Low engine oil level or use of improper
engine oil Replenish or change oil Replenish
Damaged cylinder head gasket Replace
Clogged exhaust system Clean exhaust system or replace
faulty parts
Loose fan belt Adjust
Excessive fuel injected Adjust
Engine overheating
Improper injection timing Adjust
Engine overcooling Faulty thermostat Replace
Faulty thermostat Replace Too long engine
warm-up time Thermo unit faulty Replace

SERVICE INFORMATION 00 – 15
12. ENGINE ELECTRICAL PART TROUBLE
STARTER DOES NOT RUN
CHECK BATTERY
CHARGING FAILURE OR LIFE
CHECK BATTERY
CONNECTION FAILURE
CLEAN BATTERY TERMINALS, AND RECONNECT
TURN ON HEAD LAMP AND STARTER SWITCH
HEAD LAMP DOES NOT COME ON
OR IT IS EXTREMELY DARK
a) LACK OF BATTERY CHARGING
b) SHORT-CIRCUIT IN STARTER OIL
c) FAULTY STARTER PARTS
a) DISCONNECT STARTER CIRCUIT
b) DISCONNECT STARTER COIL
c) FAULTY STARTER SWITCH
BATTERY IS NORMAL
CHECK TERMINAL CONNECTION
CHECK STARTER OR STARTER SWITCH
TERMINAL CONNECTION IS NORMAL
FAILURE
REPAIR OR REPLACE
HEAD LAMP ILLUMINATES

00 – 16 SERVICE INFORMATION
FAULTY MESHING OF PINION AND RING GEAR
CHECK IF BATTERY VOLTAGE IS PRESENT AT
MAGNETIC SWITCH TERMINAL “S” WHEN
STARTER SWITCH IS TURNED TO “START (ST)”
YES
EXTREME WEAR OF
PINION AND RING
GEAR
REPAIR OR REPLACE
STARTER, REPLACE
RING GEAR
OR
NO
UNDER THIS CONDITION, CHECK IF VOLTAGE
OF CONNECTOR 3BW ON MAGNETIC SWITCH
OF RESTART RELAY IS NORMAL
YES NO
DISCONNECTION OR
FAULTY CONNECTION
BETWEEN STARTER
SWITCH AND MAGNETIC
SWITCH
CHECK IF VOLTAGE IS
PRESENT AT WIRING
CONNECTOR 3BW ON
STARTER SWITCH OF
RESTART RELAY
STARTER SLIDING
RESISTANCE IS
LARGE
REPAIR OR REPLACE
STARTER
FAULTY CONNECTION OF
STARTER SWITCH DISCONNECTION OR FAULTY CONNECTION
BETWEEN STARTER
SWITCH AND BATTERY
REPLACE STARTER
SWITCH
REPAIR
YES NO
REPAIR

SERVICE INFORMATION 00 – 17
MAGNETIC SWITCH DOES NOT OPERATE THOUGH
STARTER SWITCH IS TURNED TO “START (ST)”
CHECK IF VOLTAGE IS PRESENT AT MAGNETIC
SWITCH TERMINAL “S” WHEN STARTER SWITCH IS
TURNED TO “START (ST)”
YESNO
CHECK GROUND CABLE
YES
YES
YES NO
REPAIR
OR
PINION
SLIDING
PART DOES
NOT MOVE
MAGNETIC SWITCH
OR COIL IS
DISCONNECTED OR
BURNED OUT
REPAIR OR REPLACE STARTER
CHECK IF INDICATOR LAMP ON
METER COMES ON NORMALLY
YES NO
DISCONNECTION OR
FAULTY CONNECTION
BETWEEN BATTERY
AND STARTER SWITCH
CHECK CONTINUITY
STARTER SWITCH AND
MAGNETIC SWITCH
TERMINAL “S”
CHECK STARTER
RELAY FAULTY CONNECTION OR STARTER SWITCH
REPAIR
CHECK CLUTCH
START REPLACE STARTER SWITCH

00 – 18 SERVICE INFORMATION
PINION MESHES WITH RING GEAR BUT
ENGINE DOES NOT RUN
CHECK GROUND CABLE
YES NO
REPAIR OR REPLACE
GROUND CABLE
FAULTY CONNECTION
OF BRUSH AND
COMMUTATOR
BURNED-OUT
MAGNETIC
STARTER SWITCH
REPAIR OR REPLACE STARTER
DISCONNECTION
OR DAMAGE OF
FIELD COIL
DISCONNECTION
OR DAMAGED OF
ARMATURE COIL
SLIP OF
PINION
CLUTCH

SERVICE INFORMATION 00 – 19
MAGNETIC SWITCH CONTACTS ARE
FUSED AND NOT MOVED, OR A
RETURN SPRING IS BROKEN OR
DETERIORATED
NO
STARTER DOES NOT STOP THOUGH STARTER
SWITCH IS RETURNED TO “ON” FROM “START”
REPLACE STARTER SWITCH
DISCONNECTED STARTER SWITCH WIRING CONNECTOR, AND CHECK STARTER SWITCH OPERATION.
KEY
POSITION BATTERY B1 IGNITION IG1 BATTERY B2 ACCESSORIES ACC IGNITION IG2 STARTER ST
LOCK
OFF
ACC
ON
START
THERE MUST BE NO CONTINUITY EXCEPT ABOVE LINES.
YES
REPLACE MAGNETIC SWITCH

00 – 20 SERVICE INFORMATION
13. TURBOCHARGER
1) ENGINE HAS LESS THAN NORMAL POWER
Checkpoint Trouble Cause Countermeasure
Air cleaner Restricted Clean or replace
Intake pipe and hose Restricted Clean or replace
Compressor/Intake manifold Loose (Leaking) Repair
Exhaust manifold/turbine inlet Loose (Leaking) Repair
Exhaust piping and silencers Restricted Clean or replace
Air breather Restricted Clean or replace
Boost compensator
(Injection pump) Defective Repair or replace
Continued on the next page
OKOK
OK
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG

SERVICE INFORMATION 00 – 21
Checkpoint Trouble Cause Countermeasure
Compressor wheel Impact damage Replace
Turbine wheel Impact damage Replace
Carbon build-up Replace
Rotating assembly Dragging or seized Replace
Continued from the previous page
OKOK
OK
NG
NG
NG
NG
OK

00 – 22 SERVICE INFORMATION
2) BLUE OR BLACK SMOKE
Checkpoint Trouble Cause Countermeasure
Air cleaner or intercooler Restricted Clean, repair, or replace
Turbocharger oil seal Leakage Replace
Turbocharger oil drain pipe Restricted Repair or replace
Air breather Restricted Clean
Boost compensator
(Injection pump) Defective Repair or replace
Compressor wheel Impact damage Replace
Turbine wheel Impact damage Replace
Continued on the next page
OKOK
OK
OK
OK
OK
OK
NG
NG
NG
NG
NG
NG
NG