Page 1835 of 6000
6B – 2 ENGINE COOLING
Legend
(1) Turbocharger
(2) Thermostat
(3) Reservoir Tank
(4) Radiator
(5) Bypass(6) Oil Cooler
(7) Cooling fan
(8) Water Pump
(9) Thermo Valve
(10) Car Heater
(11) EGR Cooler
GENERAL DESCRIPTION
COOLANT FLOW
1
6
9
9
For Europe only
10
8
4
325
7
11
032R200001
The cooling system is a pressurized coolant forced
circulation type which consists of water pump,
thermostat, cooling fan, radiator and other components. The circulating coolant cools the lubricating oil in the oil
cooler and turbocharger.
Page 1836 of 6000
ENGINE COOLING 6B – 3
WAT E R P U M P
The coolant pump is a centrifugal impeller type and is
driven by V type drive belt.
Legend
(1) Roller Bearing
(2) Ball Bearing
(3) Seal Unit
THERMOSTAT
The thermostat is a wax pellet type with a jiggle valve
and is installed in the thermostat housing.
Legend
(1) Bolt
(2) Thermostat Housing
(3) Thermostat
(4) Intake Manifold
RADIATOR
The radiator is a tube type with corrugated fins. In order
to raise the boiling point of coolant, the radiator is fitted
with a cap in which the valve is operated under the
pressure.
1
3 2
PCD 60
A06RW024
1
2
3
4
032RW002
110RS001
Page 1838 of 6000

ENGINE COOLING 6B – 5
ENGINE COOLANT CHANGE
PROCEDURE
1. To change engine coolant, make sure that the
engine is cool.
WARNING:
When the coolant is heated to a high temperature,
be sure not to loosen or remove the radiator cap.
Otherwise you might get scalded by hot vapor or
boiling water. To open the radiator cap, put a piece
of thick cloth on the cap and loosen the cap slowly
to reduce the pressure once the coolant has
become cooler.
2. Open radiator cap and drain the cooling system by
loosening the drain valve on the radiator and on the
cylinder body.
NOTE: For best results it is suggested that the engine
cooling system be flushed at least once a year. It is
advisable to flush the interior of the cooling system
including the radiator before using anti-freeze
(ethylene-glycol based).
Replace damaged rubber hoses as the engine anti-
freeze coolant is liable to leak out even minor cracks.
Isuzu recommends using Isuzu genuine anti-freeze
(ethylene-glycol based) or equivalent, for the cooling
system and not add any inhibitors or additives.
CAUTION:
A failure to correctly fill the engine cooling system
in changing or topping off coolant may sometimes
cause the coolant to overflow from the filler neck
even before the engine and radiator are completely
full.
If the engine runs under this condition, shortage of
coolant may possibly result in engine overheating.
To avoid such trouble, the following precautions
should be taken in filling the system.
3. To refill engine coolant, pour coolant up to filler neck
using a filling hose which is smaller in outside
diameter than the filler neck. Otherwise air between
the filler neck and the filling hose will block entry,
preventing the system from completely filling up.
4. Keep a filling rate of 9 liter/min. or less. Filling over
this maximum rate may force air inside the engine
and radiator.
And also, the coolant overflow will increase, making
it difficult to determine whether or not the system is
completely full.
5. After filling the system full, pull out the filling hose
and check to see if air trapped in the system is
dislodged and the coolant level goes down. Should
the coolant level go down, repeat topping-off until
there is no more drop in the coolant level.
6. Directly after filling the radiator, fill the reservoir to
the maximum level.
7. Install and tighten radiator cap and start the engine.
After idling for 2 to 3 minutes, stop the engine and
reopen radiator cap. If the water level is lower,
replenish.WARNING:
When the coolant is heated to a high temperature,
be sure not to loosen or remove the radiator cap.
Otherwise you might get scalded by hot vapor or
boiling water. To open the radiator cap, put a piece
of thick cloth on the cap and loosen the cap slowly
to reduce the pressure once the coolant has
become cooler.
8. After tightening radiator cap, warm up the engine at
about 2,000 rpm.
Set heater adjustment to the highest temperature
position, and let the coolant circulate also into
heater water system.
9. Check to see the thermostat has opened by the
needle position of a water thermometer, conduct a
5-minute idle again and stop the engine.
10. When the engine has been cooled, check filler neck
for water level and replenish if required. Should
extreme shortage of coolant be found, check the
coolant system and reservoir tank hose for leakage.
11. Fill the coolant into the reservoir tank up to “MAX”
line.
Page 1846 of 6000

ENGINE FUEL 6C – 1
ENGINE FUEL
CONTENTS
GENERAL DESCRIPTION
General Description . . . . . . . . . . . . . . . . . . 6C–1
On-Vehicle Service . . . . . . . . . . . . . . . . . . 6C–7
Fuel Filter Assembly . . . . . . . . . . . . . . . . 6C–7
Fuel Filter Cartridge . . . . . . . . . . . . . . . . 6C–7
Injector . . . . . . . . . . . . . . . . . . . . . . . . . . 6C–9
Fuel Pump Pipe . . . . . . . . . . . . . . . . . . . 6C–13High Pressure Oil Pump . . . . . . . . . . . . . 6C–15
Fuel Tank . . . . . . . . . . . . . . . . . . . . . . . . 6C–20
Fuel Gauge Unit . . . . . . . . . . . . . . . . . . . 6C–21
Fuel Filler Cap . . . . . . . . . . . . . . . . . . . . 6C–21
To realize the compatibility between low exhaust
emission and high engine output, an HEUI
(Hydraulically actuated Electronically controlled Unit
Injector) system, has been introduced. This system is
comprised of a hydraulic system, fuel system, and
electronic control system, using a high-pressure oil
pump in place of the conventional fuel injection pump.
The oil pressurized by means of this pump and by
signals from the ECM (Electronic Control Module)
actuates the fuel injector provided for each cylinder.
Inside of the fuel injector, fuel pressure is increased due
to the high-pressure oil. The ECM detects the driving
state of the vehicle, forms, signals sent by engine and
other part sensors, which determines the optimum fuel
injection amount and timing, thus controlling the fuel
injectors. Thus high engine output, good fuel economy,
and low exhaust emission are realized.When working on the fuel system, there are several
things to keep in mind:
1) Any time the fuel system is being worked on,
disconnect the negative battery cable except for
those tests where battery voltage is required.
2) Always keep a dry chemical (Class B) fire
extinguisher near the work area.
3) Replace all pipes with the same pipe and fittings
that were removed.
Clean and inspect “O” rings. Replace where
required.
4) Always relieve the line pressure before servicing
any fuel system components.
5) Do not attempt repairs on the fuel system until you
have read the instructions and checked the pictures
relating to that repair.
6) After maintenance work, push priming pump and
send enough fuel to the fuel system before starting
the engine.
NOTE: In comparison with the conventional engine,
the capacity of fuel passage in the 4JX1 engine is
larger. It takes the priming pump more time to fill the
engine with fuel.
Page 1847 of 6000
6C – 2 ENGINE FUEL
FUEL FLOW
1
14 Except above region
89
10111
2
2
4
12
5 6
7
3
13
14 For Europe, Nicaragua,
Argentina, Philippin
11
4
Legend
(1) Fuel Filler Cap
(2) Fuel Tank
(3) Rollover Valve
(4) Fuel Supply Pipe
(5) Fuel Filter with Priming Pump
(6) Fuel Pump
(7) High Pressure Oil Pump(8) Cylinder Head
(9) Injector
(10) Orifice
(11) Fuel Return Pipe
(12) Fuel Tank Pressure Release Hose
(13) Intake Air Duct
(14) Fuel Tank Pressure Control Valve
040R200001
Page 1848 of 6000
ENGINE FUEL 6C – 3
FUEL PUMP
1
2
3 4
Legend
(1) High Pressure Oil Pump
(2) To Injector(3) From Fuel Tank
(4) Fuel Pump
140RW041
Page 1849 of 6000

6C – 4 ENGINE FUEL
HIGH PRESSURE OIL PUMP, OIL FLOW
P
33
32
31
30
1
2
3
4
56
8
97
10
11
12
13
14 23 29
25
28
27262415
16
17 18
19 20 21 22
Legend
(1) Camshaft
(2) Balance Shaft
(3) Crankshaft
(4) Oil Cooler and Oil Filter Assembly
(5) Oil Filter Relief Valve 98 Kpa (1 kg/cm
2/14.2 Psi)
(6) Oil Cooler Relief Valve 245 Kpa (2.5 kg/cm2/
36 Psi)
(7) First Oil Pump
(8) Main Oil Relief Valve 588 Kpa (6 kg/cm
2/ 85 Psi)
(9) To Oil Pan
(10) To Oil Pan
(11) Injector
(12) Oil Rail
(13) Sub Oil Filter Relief Valve 98 Kpa (1 kg/cm
2/
14.2 Psi)
(14) Sub Oil Filter
(15) Relief Valve 588 Kpa (6 kg/cm
2/ 85 Psi)
(16) Second Oil Pump(17) Oil Pan
(18) To Oil Pan
(19) Balance Shaft
(20) Cooling Jet Relief Valve 245 Kpa (2.5 kg/cm
2/
36 Psi)
(21) Cooling Jet
(22) To Oil Pan
(23) Two Way Check Valve
(24) Nipple Filter
(25) Edge Filter
(26) Edge Filter
(27) High Pressure Oil Pump Assembly
(28) To Oil Pan
(29) Pressure Control Valve
(30) To Oil Pan
(31) Turbocharger
(32) Oil Gallery
(33) Timing Gear Train
040RW018
Page 1850 of 6000
ENGINE FUEL 6C – 5
FUEL FILTER
Legend
(1) Priming Pump
(2) Fuel Filter Cartridge
A cartridge type fuel filter is used along with the piston
type fuel pump on the high pressure oil pump.
The fuel filter removes foreign material from the fuel
before it reaches the fuel pump.
A diaphragm type priming pump is installed at the top of
the fuel filter. It is used during the air bleeding
procedures.
INJECTOR ASSEMBLY
Legend
(1) Oil Passage
(2) Fuel Passage
1. Construction of Fuel Injector
The fuel injector is comprised of the solenoid
section, hydraulic line, and fuel line. Fuel injection is
controlled by the continuity time signal and
continuity start timing signal sent by the ECM
(Electronic Control Module) to the solenoid.
2. Working of Fuel Injector
1) The ECM detects the working of the engine from
its input signals, such as engine speed
accelerator throttle opening, and engine coolant
temperature, sending the optimal signals to the
solenoid.
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2
041RW017
1
2
055RW018