Mitsubishi Evolution X. Manual - part 229

COOLANT

TSB Revision

ENGINE COOLING

14-3

COOLANT

M1141000401115

SEALANT

M1141000501112

ENGINE COOLING DIAGNOSIS

INTRODUCTION

M1141005300422

The system cools the engine so that it does not over-
heat and maintains the engine at an optimum tem-
perature. The system components are the radiator, 
water pump, thermostat, radiator fan and condenser 
fan assembly. Possible faults include low coolant, 
contamination, belt loosening and component dam-
age.

TROUBLESHOOTING STRATEGY

M1141005200414

Use these steps to plan your diagnostic strategy.
If you follow them carefully, you will be sure that you 
have exhausted most of the possible ways to find an 
engine cooling faults.
1. Gather information from the customer.

2. Verify that the condition described by the 

customer exists.

3. Find the malfunction by following the Symptom 

Chart.

4. Verify that the malfunction is eliminated.

SYMPTOM CHART

M1141005600650

Item

Quantity dm

3

 (qt)

Long life antifreeze coolant or an equivalent

7.5 (7.9)

Item

Specified sealant

Engine coolant temperature sensor

Three bond 1324N, LOCTITE 262 or equivalent

Symptom

Inspection procedure Reference page

Coolant leak

1

P.14-4

Engine overheating

2

P.14-5

Radiator fan and condenser fan do not operate

3

P.14-6

ENGINE COOLING DIAGNOSIS

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ENGINE COOLING

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SYMPTOM PROCEDURES

Inspection Procedure 1: Coolant Leak

DIAGNOSIS

STEP 1. Check for coolant leaks.

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 removed, be careful not to spill any 

coolant.

• When installing and removing the tester and when test-

ing, be careful not to deform the filler neck of the radia-
tor.

Check that the coolant level is up to the filler neck. Install a radi-
ator tester and apply 160 kPa (23 psi) pressure, and then check 
for leakage from the radiator hose or connections.
Q: Is leakage present from the radiator hose or 

connections?
YES : Repair or replace the appropriate part, then go to 

Step 2.

NO :  There is no action to be taken.

STEP 2. Retest the system.
Q: It there still coolant leakage?

YES : Return to Step 1.
NO :  The procedure is complete.

ACX01844AE

Cap adapter

Adapter

ENGINE COOLING DIAGNOSIS

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ENGINE COOLING

14-5

Inspection Procedure 2: Engine Overheating

DIAGNOSIS

STEP 1. Remove the radiator cap and check for coolant 
contamination.
Q: Is the coolant contaminated with rust and oil?

YES : Replace the coolant (Refer to 

P.14-17

). Then go to 

Step 5.

NO :  There is no action to be taken. Go to Step 2.

STEP 2. Check the radiator cap valve opening pressure.
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 gauge indicator stops 

moving.

Minimum limit: 83 kPa (12 psi)
Standard value: 93 

− 123 kPa (14 − 18 psi)

Q: Does the reading remain at or above the minimum limit?

YES : Go to Step 3.
NO :  Replace the radiator cap. Then go to Step 5.

STEP 3. Check thermostat operation.
Refer to 

P.14-24

.

Q: Does the thermostat operate correctly?

YES : Go to Step 4.
NO :  Replace the thermostat (Refer to 

P.14-22

). Then go to 

Step 5.

STEP 4. Check the drive belt for slippage or damage.
Refer to GROUP 00, Maintenance Service 

− Drive Belts (Check 

Condition) 

P.00-66

.

Q: Is the drive belt loose or damaged?

YES : Adjust or replace the drive belt. Then go to Step 5.
NO :  There is no action to be taken.

STEP 5. Retest the system.
Check the engine coolant temperature.
Q: Is the engine coolant temperature abnormally high?

YES : Return to Step 2.
NO :  The procedure is complete.

ACX01845AE

Cap adapter

ENGINE COOLING DIAGNOSIS

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ENGINE COOLING

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Inspection Procedure 3: Radiator Fan and Condenser Fan do not Operate

AC708832

FUSIBLE
LINK

29

FUSIBLE
LINK

28

RADIATOR 
FAN RELAY

FAN 
CONTROL
RELAY

CONDENSER
FAN RELAY

RADIATOR 
FAN 
MOTOR

CONDENSER 
FAN MOTOR

INPUT SIGNAL

ENGINE 
COOLANT 
TEMPERATURE 
SENSOR

CAN DRIVE
CIRCUIT

INTERFACE 
CIRCUIT

ENGINE 
CONTROL 
MODULE

JOINT
CONNECTOR 
(CAN3)

JOINT
CONNECTOR 
(CAN2)

INPUT SIGNAL

·FRONT WHEEL
 SPEED SENSOR
·REAR WHEEL
 SPEED SENSOR

ASC-ECU

INPUT SIGNAL

A/C SWITCH

A/C-ECU

JOINT
CONNECTOR 
(CAN1)

CAN DRIVE
CIRCUIT

INTERFACE 
CIRCUIT

ETACS-ECU

AB

Radiator Fan and Condenser Fan Drive Circuit <M/T>