Page 4596 of 6000
ENGINE COOLING6B–3
Thermostat
The thermostat is a wax pellet type with a air hole(1) and is
installed in the thermostat housing.
031RW002
Radiator
The radiator is a tube type with corrugated fins. In order to
raise the boiling point of the coolant, the radiator is fitted
with a cap in which the valve is operated at 88.2
117.6
kPa (12.8
1 7 . 0 p s i ) p r e s s u r e . ( N o o i l c o o l e r p r o v i d e d f o r
M/T)
110RS001
Anti Freeze Solution
Relation between the mixing ratio and freezing
temperature of the EC varies with the ratio of
anti–freeze solution in water. Proper mixing ratio can
be determined by referring to the chart. Supplemental
inhibitors or additives claiming to increase cooling
capability that have not been specifically approved by
Isuzu are not recommended for addition to the cooling
system.
Calculating mixing ratio
F06RW005
Page 4598 of 6000
ENGINE COOLING6B–5
Diagnosis
Engine Cooling Trouble
ConditionPossible causeCorrection
Engine overheatingLow Engine Coolant levelReplenish
Incorrect fan installedReplace
Thermo meter unit faultyReplace
Faulty thermostatReplace
Faulty Engine Coolant temperature
sensorRepair or replace
Clogged radiatorClean or replace
Faulty radiator capReplace
Low engine oil level or use of
improper engine oilReplenish or change oil
Clogged exhaust systemClean exhaust system or replace
faulty parts
Faulty Throttle Position sensorReplace throttle valve assembly
Open or shorted Throttle Position
sensor circuitRepair or replace
Damaged cylinder head gasketReplace
Engine overcoolingFaulty thermostatReplace
Engine slow to warm–upFaulty thermostatReplace
Thermo unit faultyReplace
Page 4599 of 6000

6B–6
ENGINE COOLING
Draining and Refilling Cooling
System
Before draining the cooling system, inspect the system
and perform any necessary service to ensure that it is
clean, does not leak and is in proper working order. The
engine coolant (EC) level should be between the “MIN”
and “MAX” lines of reserve tank when the engine is cold.
If low, check for leakage and add EC up to the “MAX” line.
There should not be any excessive deposit of rust or
scales around the radiator cap or radiator filler hole, and
the EC should also be free from oil.
Replace the EC if excessively dirty.
1. Completely drain the cooling system by opening the
drain plug (2) at the bottom of the radiator.
110RW002
2. Remove the radiator cap.
WARNING: TO AVOID THE DANGER OF BEING
BURNED, DO NOT REMOVE THE CAP WHILE THE
ENGINE AND RADIATOR ARE STILL HOT.
SCALDING FLUID AND STEAM CAN BE BLOWN OUT
UNDER PRESSURE.
3. Disconnect all hoses from the EC reserve tank.
Scrub and clean the inside of the reserve tank with
soap and water. Flush it well with clean water, then
drain it. Install the reserve tank and hoses.
4. Refill the cooling system with the EC using a solution
that is at least 50 percent antifreeze but no more than
70 percent antifreeze.
5. Fill the radiator to the base of the filler neck.
Fill the EC reserve tank to “MAX” line when the engine
is cold.
6. Block the drive wheels and firmly apply the parking
brake. Shift an automatic transmission to “P” (Park)
or a manual transmission to neutral.
7. Remove the radiator cap. Start the engine and warm
it up at 2,500
3,000 rpm for about 30 minutes.
8. When the air comes out from the radiator filler neck
and the EC level has gone down, replenish with the
EC. Repeat this procedure until the EC level does not
go down. Then stop the engine and install the radiator
cap. Let the engine cool down.9. After the engine has cooled, replenish with EC up to
the “MAX” line of the reserve tank.
10. Start the engine. With the engine running at 3,000
rpm, make sure there is no running water sound from
the heater core (behind the center console).
11. If the running water sound is heard, repeat steps 8 to
10.
Page 4600 of 6000

ENGINE COOLING6B–7
Water Pump
Water Pump and Associated Parts
030RS002
Legend
(1) Timing Belt
(2) Idle Pulley(3) Water Pump Assembly
(4) Gasket
Removal
1. Disconnect battery ground cable.
2. Drain coolant.
3. Radiator hose (on inlet pipe side).
4. Remove timing belt. Refer to “Timing Belt” in this
manual.
5. Remove Idle pulley.
6. Remove water pump assembly.
7. Remove gasket.
Inspection
Make necessary repair and parts replacement if extreme
wear or damage is found during inspection. Should any of
the following problems occur, the entire water pump
assembly must be replaced:
Crack in the water pump body
EC leakage from the seal unit
Play or abnormal noise in the bearing
Cracks or corrosion in the impeller.
Installation
1. Install gasket, clean the mating surface of gasket
before installation.2. Install water pump assembly and tighten bolts to the
specified torque.
Torque: 25 Nꞏm (2.5 Kgꞏm/18 lb ft)
Tightening order
The tightening order are in the illustrate.
NOTE: To prevent the oil leakage, apply the LOCTITE
262 or an equivalent, to the arrow marked fixing bolt
thread.
030RW008
Page 4602 of 6000
ENGINE COOLING6B–9
Radiator
Radiator and Associated Parts
110RW003
Legend
(1) Oil Cooler Hose For Automatic Transmission
(2) Radiator Hose
(3) Fan Guide, Lower(4) Reserve Tank Hose
(5) Bracket
(6) Radiator Assembly
(7) Reserve Tank
Removal
1. Disconnect battery ground cable.
2. Loosen a drain plug(2) to drain EC.
3. Disconnect oil cooler hose(1) on automatic
transmission (A/T).
4. Disconnect radiator inlet hose and outlet hose from
the engine.
110RW002
5. Remove fan guide(1), clips(3) on both sides and the
bottom lock, then remove lower fan guide(3) with fan
shroud(4).
110RW001
Page 4604 of 6000

ENGINE COOLING6B–11
Cap tester: 5–8840–0277–0
Adapter: 5–8840–2603–0
110RS005
Installation
1. Install rubber cushions on both sides of radiator
bottom.
2. Install radiator assembly with hose, taking care not to
damage the radiator core with a fan blade.
3. Install bracket (6) and support the radiator upper tank
with the bracket (5) and secure the radiator.
4. Connect reserve tank hose (4).
5. Install lower fan guide (3).
6. Connect radiator inlet hose and outlet hose to the
engine.
7. Connect oil cooler hose (1) to automatic
transmission.
110RW004
8. Connect battery ground cable.
9. Pour engine coolant up to filler neck of radiator, and
up to MAX mark of reserve tank.
111 R S 0 0 1Important operation (in case of 100% engine coolant
change) procedure for filling with engine coolant.
1. Make sure that the engine is cool.
2. Open radiator cap pour coolant up to filler neck.
3. Pour coolant into reservoir tank up to “MAX” line.
4. 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
WHEN THE COOLANT HAS BECOME COOLER.
5. After tightening radiator cap, warm up the engine
at about 2000 rpm. Set heater adjustment to the
highest temperature position, and let the coolant
circulate also into heater water system.
6. Check to see the thermostat has opened through
the needle position of water thermometer,
conduct a 5–minute idling again and stop the
engine.
7. When the engine has been cooled, check filler
neck for water level and replenish if required.
Should extreme shortage of coolant is found,
check the cooling system and reservoir tank hose
for leakage.
8. Pour coolant into reservoir tank up tp “MAX” line.
Page 4610 of 6000

6C–3
ENGINE FUEL
Adhere to all Notices and Cautions.
All gasoline engines are designed to use only unleaded
gasoline. Unleaded gasoline must be used for proper
emission control system operation.
Its use will also minimize spark plug fouling and extend
engine oil life. Using leaded gasoline can damage the
emission control system and could result in loss of
emission warranty coverage.
All cars are equipped with an Evaporative Emission
Control System. The purpose of the system is to minimize
the escape of fuel vapors to the atmosphere.
Fuel Metering
The Engine Control Module (ECM) is in complete control
of this fuel delivery system during normal driving
conditions.
The intake manifold function, like that of a diesel, is used
only to let air into the engine. The fuel is injected by
separate injectors that are mounted over the intake
manifold.
The Manifold Absolute Pressure (MAP) sensor measures
the changes in the intake manifold pressure which result
from engine load and speed changes, which the MAP
sensor converts to a voltage output.
This sensor generates the voltage to change
corresponding to the flow of the air drawn into the engine.
The changing voltage is transformed into an electric
signal and provided to the ECM.
With receipt of the signals sent from the MAP sensor,
Intake Air Temperature sensor and others, the ECM
determines an appropriate fuel injection pulse width
feeding such information to the fuel injector valves to
effect an appropriate air/fuel ratio.
The Multiport Fuel Injection system utilizes an injection
system where the injectors turn on at every crankshaft
re vol u tion . Th e EC M con tro ls t he in je cto r on tim e so t ha t
the correct amount of fuel is metered depending on
driving conditions.
Two interchangeable “O” rings are used on the injector
that must be replaced when the injectors are removed.
The fuel rail is attached to the top of the intake manifold
and supplies fuel to all the injectors.
Fuel is recirculated through the rail continually while the
engine is running. This removes air and vapors from the
fuel as well as keeping the fuel cool during hot weather
operation.
The fuel pressure control valve that is mounted on the fuel
rail maintains a pressure differential across the injectors
under all operating conditions. It is accomplished by
controlling the amount of fuel that is recirculated back to
the fuel tank based on engine demand.
See Section “Driveability and Emission” for more
information and diagnosis.
Page 4616 of 6000

6C–9
ENGINE FUEL
2. For removal of the delivery pipe (feeding fuel to the
engine), hold the connector in one hand, and hold the
retainer tab with the other hand and pull out the
connector, as illustrated. The pipe can be removed
with the retainer attached.
141RW019
3. For removal of the return pipe (returning fuel to the
tank), hold the pipe in one hand, and pull out the
connentor with the other hand while pressing the
square relieve button of the retainer, as illustrated.
141RW020
NOTE: This work should be done by hands. Do not use
any tools. Should the pipe can hardly be removed from
the connector, use a lubricant (light oil) and/or push and
pull the connector longitudinally until the pipe is removed.
141RW021When reusing the delivery pipe retainer, reuse
without removing the retainer from the pipe. If the
retainer is damaged or deformed, however, replace
with a new retainer.
Cover the connectors removed with a plastic bag, etc.
to prevent the entry of dust or rain water.
141RW022