GENERAL INFORMATION
ENGINE COOLING14-2
GENERAL INFORMATION
M1141000100371The 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 alternator drive belt from the
crankshaft. The radiator is the corrugated fin, down
flow type.
SERVICE SPECIFICATIONS
M1141000300416
LUBRICANT
M1141000400338
ItemSpecification
Radiator Performance kJ/h 4G13 Standard vehicles 137,720
Vehicles with capacity up radiator
(option)161,288
4G18 Standard vehicles 161,288
Vehicles with capacity up radiator
(option)181,800
4G63 181,800
A/T oil cooler Performance kJ/h 5,651
Item Standard value Limit
High-pressure valve opening pressure of radiator cap kPa 93 − 123 Minimum 83
Range of coolant antifreeze concentration of radiator % 30 − 60 -
Thermostat Valve opening temperature of
thermostat °C4G1 88 ± 1.5 -
4G6 82 ± 1.5 -
Full-opening temperature of
thermostat °C4G1 100 -
4G6 95 -
Valve lift mm 8.5 or more -
Item Specified coolant Quantity L
Engine coolant (including
condense tank)DIAQUEEN SUPER LONG LIFE COOLANT
or an equivalent4G1 5.0
4G6 7.0
ON-VEHICLE SERVICE
ENGINE COOLING14-22
ON-VEHICLE SERVICE
ENGINE COOLANT LEAK CHECKM1141001000300
WARNING
When pressure testing the cooling system,
slowly release cooling system pressure to
avoid getting burned by hot coolant.
CAUTION
•Be sure to completely clean away any
moisture from the places checked.
•When the tester is taken out, be careful not to
spill any coolant.
•Be careful when installing and removing the
tester and when testing not to deform the
filler neck of the radiator.
1. Check that the coolant level is up to the filler neck.
Install a radiator tester and apply 160 kPa
pressure, and then check for leakage from the
radiator hose or connections.
2. If there is leakage, repair or replace the
appropriate part.
RADIATOR CAP VALVE OPENING
PRESSURE CHECK
M1141001300389
NOTE: Be sure that the cap is clean before
testing. Rust or other foreign material on the cap
seal will cause an improper reading.
1. Use a cap adapter to attach the cap to the tester.2. Increase the pressure until the indicator of the
gauge stops moving.
Minimum limit: 83 kPa
Standard value: 93 − 123 kPa
3. Replace the radiator cap if the reading does not
remain at or above the limit.
ENGINE COOLANT REPLACEMENTM1141001200434
WARNING
When removing the radiator cap, use care to
avoid contact with hot coolant or steam.
Place a shop towel over the cap and turn the
cap counterclockwise a little to let the
pressure escape through the vinyl tube.
After relieving the steam pressure, remove
the cap by slowly turning it
counterclockwise.
1. Drain the water from the radiator, heater core and
engine after unplugging the radiator drain plug
and removing the radiator cap.
2. Drain the water in the water jacket by unplugging
the drain plug of the cylinder block.
3. Remove the radiator condenser tank and drain
the coolant.
4. Drain the coolant then clean the path of the
coolant by injecting water into the radiator from
the radiator cap area.
ACX01844
Cap adapter
Adapter
AC
AC211643AB
Cap adapter
AC208283AC
Cylinder block
drain plug
<4G1>
Inlet side
AC303355
<4G6>
Inlet side
Cylinder block
drain plug
AB
ON-VEHICLE SERVICE
ENGINE COOLING14-23
5. Apply the designated sealant to the screw area of
the cylinder block drain plug, and then tighten to
the standard torque.
Specified sealant: 3M Nut Locking Part
No.4171 or equivalent
Tightening torque:
40 ± 5 N⋅m <4G1>
44 ± 5 N⋅m <4G6>
6. Securely tighten the drain plug of the radiator.
7. Reinstall the radiator condenser tank.
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 corrosion of the aluminium
components.
8. By referring to the section on coolant, select an
appropriate concentration for safe operating
temperature within the range of 30 to 60%. Use
special tool LLC changer (MB991871) to refill the
coolant. A convenient mixture is a 50% water and
50% antifreeze solution (freezing point: −31°C).
Recommended antifreeze: DIAQUEEN SUPER
LONG LIFE COOLANT or equivalent
Quantity:
5.0 L <4G1>
7.0 L <4G6>
NOTE: For how to use special tool MB991871,
refer to its manufacturer’s instructions.9. Reinstall the radiator cap.
10.Start the engine and let it warm up until the
thermostat opens.
11.After repeatedly revving the engine up to 3,000
r/min several times, then stop the engine.
12.Remove the radiator cap after the engine has
become cold, and pour in coolant up to the brim.
Reinstall the cap.
CAUTION
Do not overfill the radiator condenser tank.
13.Add coolant to the radiator condenser tank
between the "F" and "L" mark if necessary.
CONCENTRATION MEASUREMENTM1141001100352
Measure the temperature and specific gravity of the
engine coolant to check the antifreeze concentration.
Standard value: 30 − 60% (allowable
concentration range)
Recommended antifreeze: DIAQUEEN SUPER
LONG LIFE COOLANT or equivalent
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.
COOLING FAN MOTOR DRIVE CONTROL
UNIT CHECK
M1141006100216
1. Remove the cooling fan motor drive control unit
connector.
2. Turn the ignition switch to the "ON" position, and
measure the voltage between terminal 1 and 3 at
the harness side connector.
Standard value: system voltage
AC200625
Cylinder block
drain plug
AC
AC303612AB
MB991871
AIR HOSE
AC103195
Y1716AU
1 23
AC
Cooling fan motor
drive control unit
ON-VEHICLE SERVICE
ENGINE COOLING14-24
3. Connect the cooling fan motor drive control unit
connector, and disconnect the cooling fan motor
(L.H.) connector.
4. Ensure that the A/C switch is off, and start the
engine and run it at idle.
5. Measure the voltage between the cooling fan
motor drive control unit side connector terminal 1
and 2.
Standard value: 1V or less
WARNING
Stay clear of the fan when the fan starts
running.
6. Turn the A/C switch to the "ON" position.
7. Measure the voltage between the cooling fan
motor drive control unit side connector terminal 1
and 2 while the fan is running. The voltage should
repeat the values below.
Standard value:
1. 1 V or less
2. 8.2 ± 0.7 V
3. System voltage ± 2.6 V
8. If the voltage does not repeatedly change as
indicated, replace the cooling fan motor drive
control unit. (Refer to P.14-35).
FAN CONTROL RELAY CONTINUITY
CHECK
M1141006200280
AC303496AB
Cooling fan motor
drive control unit
Battery
voltageTerminal No.to
be connected to
testerContinuity test
results
Not applied 4 − 2 Open circuit
Connect
terminal
No.1 and
battery (−)
terminal.
Connect
terminal
No.3 and
battery (+)
terminal.4 − 2 Less than 2 ohms
AC211776
13
4 2
3 4
1 2
AC301712
Fan control relay
AB
ON-VEHICLE SERVICE
ENGINE COOLING14-25
COOLING FAN MOTOR CHECKM11410071000601. Remove the cooling fan motor connector.
2. Check to see that the cooling fan motor of the
radiator turns when applying battery power
between the connector terminal 1 and 2 of the
cooling fan motor. Also check to see that there is
no abnormal sound coming from the cooling fan
motor at this time.
3. If the cooling fan motor is defective, replace it.
(Refer to P.14-35).
1 2
AC303501AB
Cooling fan motor drive control unit
Cooling fan motor
(L.H.) connector
1 2
AC303502AB
Cooling fan motor
drive control unit
Cooling fan motor
(R.H.) connector
<4G1 with A/C>
THERMOSTAT
ENGINE COOLING14-27
REMOVAL SERVICE POINT
<> RADIATOR LOWER HOSE
DISCONNECTION
Make mating marks on the radiator lower hose and
the hose clamp. Disconnect the radiator lower hose.
INSTALLATION SERVICE POINTS
>>A<< THERMOSTAT INSTALLATION
CAUTION
Make absolutely sure that no oil adheres to the
rubber ring of the thermostat. Also do not fold or
scratch the rubber ring during installation.
Install the thermostat so that the jiggle valve is facing
straight up. Be careful not to fold or scratch the
rubber ring.
>>B<< RADIATOR LOWER HOSE
CONNECTION
1. Insert radiator lower hose as far as the projection
of the Cooling water inlet hose fitting.
2. Align the mating marks on the radiator lower hose
and hose clamp, and then connect the radiator
lower hose.
INSPECTIONM1141002500427
THERMOSTAT CHECK
1. Immerse the thermostat in water, and heat the
water while stirring. Check the thermostat valve
opening temperature.
Standard value:
88 ± 1.5°C <4G1>
82 ± 1.5°C <4G6>
Removal steps
1. Water temperature gauge unit
connector <4G6>
2. Water temperature sensor unit
connector <4G6>
<> >B<<3. Radiator lower hose connection4. Engine control oxygen sensor
connector and connector bracket
<4G1>
5. Control wiring harness clip <4G6>
6. Cooling water inlet hose fitting>>A<<7. ThermostatRemoval steps (Continued)
AC200641AC
Mating marks
AC000279
Jiggle valve
Rubber ring
AB
AC200642
Mating marks
Projection
Cooling water inlet
hse fitting
AH
ACX00400
AB
WAT ER P U M P
ENGINE COOLING14-29
WAT E R P U M P
REMOVAL AND INSTALLATION <4G1>M1141002700421
INSTALLATION SERVICE POINT
>>A<< WATER PUMP ASSEMBLY
INSTALLATION
1. Use a gasket scraper or wire brush to completely
eliminate all gasket material on the gasket
mounting surface.2. Apply a bead of the specified sealant.
Specified Sealant: MITSUBISHI GENUINE
PART No.MD970389 or equivalent
3. With the sealant still wet (within 15 minutes after
the sealant is applied), install the water pump
assembly. Do not apply the sealant in an area
more than the required.
Pre-removal and Post-installation Operation
•Engine Coolant Draining and Refilling (Refer to P.14-22).
•Valve Timing Belt Removal and Installation (Refer to
GROUP 11A P.11A-33).
AC303372
24 ± 3 N·m 23 ± 2 N·m
14 ± 1 N·m
1
2
Bolt specifications
Screw diameter × length mm 8 × 50
8 × 308 × 25
AB
2
2
Sealant: Mitsubishi Genuine Part
No. MD970389 or equivalent
Removal steps
1. Alternator adjusting brace
>>A<<2. Water pump assembly
WAT E R P U M P
ENGINE COOLING14-30
REMOVAL AND INSTALLATION <4G6>M1141002700432
INSTALLATION SERVICE POINT
>>A<< COOLING WATER LINE O-RING
INSTALLATIONFit the cooling water line O-ring to the groove in the
water pump inlet pipe. Then lubricate the cooling
water line O-ring and the inside of the water pump
assembly with water, and then insert the water pump
inlet pipe to the water pump assembly.
Pre-removal and Post-installation Operation
•Engine Coolant Draining and Refilling (Refer to P.14-22).
•Valve Timing Belt and Balancer Timing Belt Removal and
Installation (Refer to GROUP 11C P.11C-35).
AC301467
22 ± 4 N·m
23 ± 3 N·m
14 ± 1 N·m
12
3 4
N
N
Bolt specifications
Screw diameter × length mm
8 × 708 × 22
8 × 14
8 × 22 8 × 25
2
AB
Removal steps
1. Alternator adjusting brace
2. Water pump assembly3. Water pump gasket
>>A<<4. Cooling water line O-ringRemoval steps (Continued)
AC103005
Water pump assembly
Cooling water
line O-ring
Water pump inlet pipe
AF