Page 689 of 1449
14-1
ENGINE COOLING
CONTENTS
GENERAL INFORMATION 2..................
SERVICE SPECIFICATIONS 2.................
LUBRICANT 2...............................
SEALANT 2..................................
SPECIAL TOOLS 3...........................
TROUBLESHOOTING 3.......................
ON-VEHICLE SERVICE 6.....................
Engine Coolant Leak Checking 6................
Radiator Cap Opening Pressure Check 6........Engine Coolant Replacement 6..................
Concentration Measurement 7...................
Radiator Fan Relay Continuity Check 8..........
Radiator Fan Controller Check 8................
Radiator Fan Motor Check 10...................
THERMOSTAT 11............................
WATER PUMP 13............................
WATER HOSE AND WATER PIPE 14..........
RADIATOR 15................................
Page 690 of 1449

ENGINE COOLING -GeneralInformation/
Service Specifications/Lubricant/Sealant14-2
GENERAL INFORMATION
The cooling system is designed to keep every part
of the engine at appropriate temperature in
whatever condition the engine may be operated.
The cooling method is of the water-cooled, pressure
forced circulation type in which the water pump
pressurizes coolant and circulates it throughout the
engine. If the coolant temperature exceeds the
prescribed temperature, the thermostat opens to
circulate the coolant through the radiator as well
so that the heat absorbed by the coolant may be
radiated into the air.The water pump is of the centrifugal type and is
driven by the drive belt from the crankshaft.
The radiator is the corrugated fin, down flow type.
The cooling fan is controlled by the radiator fan
controller and engine-ECU depend on driving
conditions.
ItemSpecification
Radiator performance kJ/h216,700
SERVICE SPECIFICATIONS
ItemsStandard valueLimit
Radiator cap opening pressure kPa93 - 12383
Range of coolant antifreeze concentration of radiator %30 - 60-
ThermostatValve opening temperature of thermostat_C80±1.5-
Full-opening temperature of thermostat_C93-
Valve lift (at 93_C) mm9.5 or more-
LUBRICANT
ItemSpecified coolantQuantity L
Engine coolantMITSUBISHI GENUINE COOLANT or equivalent6.0Enginecoolant
(including reserve tank)
MITSUBISHIGENUINECOOLANTorequivalent6.0
SEALANT
ItemSpecified sealantRemark
Cylinder block drain plug3M Nut Locking Part No. 4171 or equivalentDrying sealant
Page 691 of 1449

ENGINE COOLING -Special Tools/Troubleshooting14-3
SPECIAL TOOLS
ToolNumberNameUse
A
B
C
DMB991223
A: MB991219
B: MB991220
C: MB991221
D: MB991222Harness set
A: Test harness
B: LED harness
C: LED harness
adapter
D: ProbeDMeasurement of terminal voltage
DInspection of radiator fan controller
A: Connector pin contact pressure
inspection
B: Power circuit inspection
C: Power circuit inspection
D: Commercial tester connection
MB991658Test harnessInspection of radiator fan controller
APS
MB991791Throttle cotrollerInspection of radiator fan controller
[Use the accelerator pedal position sensor
disconnected from harness.]
TROUBLESHOOTING
INSPECTION CHART FOR TROUBLE SYMPTOMS
Trouble symptomsInspection procedure
No.Reference page
Radiator fan does not operate.114-3
Radiator fan does not change speed or stop.214-5
INSPECTION PROCEDURE FOR TROUBLE SYMPTOMS
Inspection Procedure 1
Radiator fan does not operate.
Probable cause
Failure may occur on the power supply of the radiator fan controller and the
earth circuit.
Failure may also occur on the radiator fan controller and engine-ECU.DMalfunction of fusible link
DMalfunction of radiator fan relay
DMalfunction of radiator fan controller
DMalfunction of radiator fan motor
DMalfunction of engine-ECU
DMalfunction of harness, connector
Page 692 of 1449

ENGINE COOLING -Troubleshooting14-4
Measure at the engine-ECU connector C-126.
DConnect the connector.
DPull out the teminal No.21 to disconnect it
(Ignition switch: ON)
OK:Radiator fan motor is rotated.
YES
Engine-ECU terminal voltage check
(Refer to GROUP 13A - Troubleshooting.)NO
Replace the radiator fan controller.
NG
Repair
OK
NG
Repair
OK
Check the harness wire between radiator fan controller and
engine-ECU.
Measure at the engine-ECU connector C-126.
DConnect the connector.
DVoltage between terminal 21 and body earth
(Engine: Idling, engine coolant temperature: 95_C or more)
OK:0.7 V or more
DConnect the connector.
DVoltage between terminal 21 and body earth
(Engine: Idling, A/C switch: ON)
OK:0.7 V or more (When A/C compressor is operating)NG
(2) NGCheck the harness wire between radiator fan controller and
body earth, and repair if necessary.
OK
Measure at the radiator fan controller connector A-21.
DDisconnect the connector, and measure at the harness
side.
(1) Voltage between terminal 3 and body earth
(Ignition switch: ON)
OK:Battery voltage
(2) Continuity between terminal 1 and body earth
OK:Continuity(1) NGCheck the harness wire between radiator fan controller and
radiator fan relay, and repair if necessary.
(3) NGCheck the harness wire between radiator fan relay and body
earth, and repair if necessary.
(2) NGCheck the harness wire between radiator fan relay and engine
control relay, and repair if necessary.
OK
Measure at the radiator fan control relay connector A-09X.
DRemove the relay, and measure at the relay box side.
(1) Voltage between terminal 4 and body earth
OK:Battery voltage
(2) Voltage between terminal 1 and body earth
(Ignition switch: ON)
OK:Battery voltage
(3) Continuity between terminal 3 and body earth
OK:Continuity(1) NGCheck the harness wire between radiator fan relay and fusible
link (2), and repair if necessary.
DFusible link (2) check
DRadiator fan relay continuity check
(Refer to P.14-8.)
DRadiator fan motor check (Refer to P.14-10.)NG
Replace
OK
OK
Engine-ECU terminal voltage check
(Refer to GROUP 13A - Troubleshooting.)
Check the following connectors:
C-126, A-13, A-21
C-126, C-136, A-21
NG
Check the trouble symptoms.
Page 693 of 1449

ENGINE COOLING -Troubleshooting14-5
Inspection Procedure 2
Radiator fan does not change speed or stop.
Probable cause
Radiator fan controller uses the signal from engine-ECU to control radiator fan
motor in a continously variable mode.DMalfunction of radiator fan relay
DMalfunction of radiator fan controller
DMalfunction of engine-ECU
DMalfunction of harness, connector
Measure at the engine-ECU connector C-126.
DConnect the connector.
DPull out the teminal No.21 to disconnect it
(Ignition switch: ON)
OK:Radiator fan motor is rotated.
DConnect the teminal No.21 to the body earth
(Ignition switch: ON)
OK:Radiator fan motor stop running.
YES
Engine-ECU terminal voltage check
(Refer to GROUP 13A - Troubleshooting.)NO
Replace the radiator fan controller.
OK
Radiator fan controller check (Refer to P.14-8.)NGReplace the radiator fan controller.
OK
Measure at the engine-ECU connector C-126.
DConnect the connector.
DVoltage between terminal 21 and body earth
(Engine: Idling, engine coolant temperature: 80_C or less)
OK:0 - 0.3 V
(Engine: Idling, engine coolant temperature: 95_C or more)
OK:0.7 V or more
DConnect the connector.
DVoltage between terminal 21 and body earth
(Engine: Idling, engine coolant temperature: 80_C or less)
OK:0 - 0.3 V
(Engine: Idling, A/C switch: ON)
OK:0.7 V or more (When A/C compressor is operating)NG
OK
DCheck the harness wire between radiator fan relay and
engine control relay.
DCheck the harness wire between radiator fan relay and
body earth.
DCheck the harness wire between radiator fan relay and
radiator fan controller.NG
Repair
NG
Replace
OK
OK
OK
Check the following connectors:
C-126, A-13, A-21
C-126, C-136, A-21
NG
Engine-ECU terminal voltage check
(Refer to GROUP 13A - Troubleshooting.)
Check the trouble symptoms.
NG
NG
Repair
Repair
Radiator fan relay continuity check (Refer to P.14-8.)
Check the harness wire between radiator fan controller and
engine-ECU.
Page 694 of 1449

ENGINE COOLING -On-vehicle Service14-6
ON-VEHICLE SERVICE
ENGINE COOLANT LEAK CHECKING
1. Confirm that the coolant level is up to the filler neck.
Install a radiator cap tester and apply 160 kPa pressure,
and then check for leakage from the radiator hose or
connections.
Caution
(1) Be sure to completely clean away any moisture
from the places checked.
(2) When the tester is taken out, be careful not to
spill any coolant from it.
(3) Be careful, when installing and removing the tester
and when testing, not to deform the filler neck
of the radiator.
2. If there is leakage, repair or replace the appropriate part.
RADIATOR CAP OPENING PRESSURE CHECK
1. Use a cap adapter to attach the cap to the tester.
2. Increase the pressure until the indicator of the gauge
stops moving.
Limit: 83 kPa
Standard value: 93 - 123 kPa
3. Replace the radiator cap if the reading does not remain
at or above the limit.
NOTE
Be sure that the cap is clean before testing, since rust
or other foreign material on the cap seal will cause an
improper indication.
ENGINE COOLANT REPLACEMENT
1. Remove the under cover.
(Refer to GROUP 51 - Front Bumper.)
2. Drain the engine coolant by removing the drain plug and
then the radiator cap.
Cap adapter
Adapter
Cap adapter
Page 695 of 1449

ENGINE COOLING -On-vehicle ServiceENGINE COOLING -On-vehicle Service14-7
3. Remove the cylinder block drain plug from the cylinder
block to drain the engine coolant.
4. Remove the reserve tank to drain the engine coolant.
5. When the engine coolant has drained, pour in water from
the radiator cap to clean the engine coolant line.
6. Coat the thread of the cylinder block drain plug with the
specified sealant and tighten to the specified torque.
Specified sealant:
3M Nut Locking Part No. 4171 or equivalent
7. Securely tighten the radiator drain plug.
8. Install the under cover.
(Refer to GROUP 51 - Front Bumper.)
9. Install the reserve tank.
10. Slowly pour the engine coolant into the mouth of the
radiator until the radiator is full, and pour also into the
reserve tank up to the FULL line.
Recommended anti-freeze:
MITUBISHI GENUINE COOLANT or equivalent
Quantity: 6.0 L
Caution
Do not use alcohol or methanol anti-freeze or any
engine coolants mixed with alcohol or methanol
anti-freeze. The use of an improper anti-freeze can
cause the corrosion of the aluminium components.
11. Install the radiator cap securely.
12. Start the engine and warm the engine until the thermostat
opens. (Touch the radiator hose with your hand to check
that warm water is flowing.)
13. After the thermostat opens, race the engine several times,
and then stop the engine.
14. Cool down the engine, and then pour engine coolant into
the reserve tank until the level reaches the FULL line. If
the level is low, repeat the operation from step 11.
CONCENTRATION MEASUREMENT
Measure the temperature and specific gravity of the engine
coolant to check the antifreeze concentration.
Standard value: 30 - 60 % (allowable concentration range)
RECOMMENDED ANTI-FREEZE
AntifreezeAllowable concentration
MITSUBISHI GENUINE COOLANT
or equivalent30 - 60 %
Caution
If the concentration of the anti-freeze is below 30 %, the
anti-corrosion property will be adversely affected. In
addition, if the concentration is above 60 %, both the
anti-freezing and engine cooling properties will decrease,
affecting the engine adversely. For these reasons, be
sure to maintain the concentration level within the
specified range.
44±5N·m
Water inlet
pipe
Page 696 of 1449
ENGINE COOLING -On-vehicle Service14-8
RADIATOR FAN RELAY CONTINUITY CHECK
Battery voltageTerminal No.
1234
When current is not
supplied
When current is
supplied
RADIATOR FAN CONTROLLER CHECK
1. Remove the center under cover.
(Refer to GROUP 51 - Front Bumper.)
2. Insert the special tool at the back of the radiator fan
motor connector.
3. Connect the special tool to the circuit tester.
4. Disconnect the engine coolant temperature sensor
connector.
Air cleaner
Radiator fan
controller
MB991222
Circuit tester
Connector
rear view
Water outlet
fitting
Engine coolant
temperature
sensor