17

COOLING SYSTEM CONCERNS-OVERHEATING

DESCRIPTION

• Engine runs at higher than normal temperature/overheats.

POSSIBLE CAUSE

• Engine heat generation amount is excessive

• Engine speed is high and remains high for continuous long periods

• PCM DTC is stored

• Improper indication of low engine coolant temperature indicator light and/or high engine coolant temperature warning light

• ECT sensor No.1 malfunction

• Instrument cluster malfunction

• Improper operation of A/C system

• Cooling fan inoperative

• Improper engine coolant level

• Coolant leakage (engine internal, external)

• Engine coolant performance deterioration

• Improper water/anti-freeze mixture

• Poor radiator condition

• Radiator hose damage

• Improper or damaged radiator cap

• Coolant overflow system malfunction

• Fans reverse rotation

• Blown fuse

• Leakage at coolant hoses and/or radiator

• Leakage around heater unit in passenger compartment

• Drive belt damage

• Improper drive belt tension

• Thermostat malfunction

• Excessive A/C system pressure

Item (definition)

Unit/Condition

Definition

Condition/Specification (Reference)

ECT

°C, °F

Engine coolant temperature (No.1)

• Displays ECT

V

• ECT is 20 °C {68 °F}: Approx. 3.10 V

• ECT is 40 °C {104 °F}: Approx. 2.16 V

• ECT is 60 °C {140 °F}: Approx. 1.40 V

• ECT is 80 °C {176 °F}: Approx. 0.87 V

• ECT is 100 °C {212 °F}: Approx. 0.54 V

STEP

INSPECTION

RESULTS

ACTION

1

• Verify how the customer drives the vehicle by asking the customer the following:

• Engine speed is high and remains high for continuous long periods like when climbing a long, steep grade.

• Is the engine generating excessive heat when driven?

Yes

Explain to the customer that the vehicle is normal and give them advice how to use vehicle and provide a specific example of the conditions in which the engine overheats.

No

Go to the next step.

2

• Start the engine and run it at idle speed.

• Turn the A/C switch off.

• Does the A/C compressor disengaged?

Yes

Go to the next step.

No

Perform the symptom troubleshooting “NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY”.

(See NO.24 A/C IS ALWAYS ON OR A/C COMPRESSOR RUNS CONTINUOUSLY [SKYACTIV-G 2.5].)

3

• Retrieve any DTCs using the M-MDS.

  (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].)

• Are any DTCs present?

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [SKYACTIV-G 2.5].)

No

Go to the next step.

4

• Access the ECT PID using the M-MDS.

  (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].)

• Compare the ECT PID and low engine coolant temperature indicator light and high engine coolant temperature warning light operation.

• Is the ECT PID value same as indicator/warning light readings?

Yes

Go to the next step.

No

Inspect the ECT sensor No.1.

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G 2.5].)

• If there is any malfunction:

• Replace the ECT sensor No.1.

  (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

• If there is no malfunction:

• Perform the instrument cluster symptom troubleshooting “LOW ENGINE COOLANT TEMPERATURE INDICATOR LIGHT/HIGH ENGINE COOLANT TEMPERATURE WARNING LIGHT ILLUMINATES OR FLASHES CONTINUOUSLY”.

  (See LOW ENGINE COOLANT TEMPERATURE INDICATOR LIGHT/HIGH ENGINE COOLANT TEMPERATURE WARNING LIGHT ILLUMINATES OR FLASHES CONTINUOUSLY [INSTRUMENT CLUSTER].)

5

• Perform the Cooling Fan Control System Inspection.

  (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [SKYACTIV-G 2.5].)

• Does the cooling fan control system operate properly?

Yes

Go to the next step.

No

Repair or replace the malfunctioning part according to the inspection results.

6

• Inspect the following:

• Engine coolant level

• Engine coolant performance

• Water and anti-freeze mixture

• Radiator condition

• Collapsed or restricted radiator hoses

• Radiator pressure cap

• Coolant overflow system

• Fan rotational direction

• Fuses

• Is there any malfunction?

Yes

Service if necessary.

• Repeat this step.

No

Go to the next step.

7

• Inspect for leakage at coolant hoses and/or radiator.

• Is there any leakage?

Yes

Repair or replace the malfunctioning part according to the inspection results.

No

Go to the next step.

8

• Inspect for leakage around heater unit in passenger compartment.

• Is there any leakage?

Yes

Repair or replace the malfunctioning part according to the inspection results.

No

Go to the next step.

9

• Inspect the drive belt.

  (See DRIVE BELT INSPECTION [SKYACTIV-G 2.5].)

• Is there any malfunction?

Yes

Replace the drive belt.

(See DRIVE BELT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

No

Go to the next step.

10

• Cool down the engine.

• Remove the thermostat.

  (See THERMOSTAT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

• Inspect the thermostat operation.

  (See THERMOSTAT INSPECTION [SKYACTIV-G 2.5].)

• Is there any malfunction?

Yes

Replace the thermostat.

(See THERMOSTAT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

No

Reinstall the thermostat.

(See THERMOSTAT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)

The engine coolant temperature and thermostat are normal.

• Inspect the engine block for leakage or blockage.

• Repair or replace the malfunctioning part according to the inspection results.

11

Verify the test results.

• If normal, return to the diagnostic index to service any additional symptoms.

  (See SYMPTOM DIAGNOSTIC INDEX [SKYACTIV-G 2.5].)

• If the malfunction remains, inspect the related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.

• If the vehicle is repaired, troubleshooting is completed.

• If the vehicle is not repaired or additional diagnostic information is not available, reprogram the PCM if a later calibration is available. Retest.