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 operation of A/C system

• Insufficient air blow volume

• Cooling fan inoperative

• Fan rotation speed decreases (such as generator malfunction) due to battery voltage decrease

• Cooling system cap malfunction

• Cooling fan motor assembly malfunction

• Cooling fan motor connector malfunction

• 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

• Blown fuse

• Engine coolant system malfunction

• Engine coolant performance deterioration

• Coolant leakage (engine internal, external)

• Improper water/anti-freeze mixture

• Thermostat malfunction (not fully open)

• Radiator malfunction (clogging)

• Improper engine coolant level

• Leakage around heater unit in passenger compartment

• Drive belt damage

Item (definition)

Unit/Condition

Definition

Condition/Specification (Reference)

ECT

°C, °F

Engine coolant temperature input from ECT sensor No.1

• Displays ECT

V

ECT sensor No.1 voltage

Ignition switched ON (engine off)

• ECT is 92 °C {198 °F}: Approx. 0.65 V

Idle (after warm up)

• ECT is 93 °C {199 °F}: Approx. 0.64 V

Racing (Engine speed is 2,000 rpm)

• ECT is 92 °C {198 °F}: Approx. 0.66 V

Racing (Engine speed is 4,000 rpm)

• ECT is 93 °C {199 °F}: Approx. 0.64 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

• Retrieve any DTCs using the M-MDS.

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

• Are any DTCs present?

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [PCM (SKYACTIV-G 2.0)].)

No

Go to the next step.

3

• 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 2.0].)

4

• Access the ECT PID using the M-MDS.

  (See ON-BOARD DIAGNOSTIC TEST [PCM (SKYACTIV-G 2.0)].)

• 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 2.0].)

• If there is any malfunction:

• Replace the ECT sensor No.1.

  (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

• 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 2.0].)

• 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 cooling system cap.

  (See COOLING SYSTEM CAP INSPECTION [SKYACTIV-G 2.0].)

• Is there any malfunction?

Yes

Replace the cooling system cap.

No

Go to the next step.

7

• Inspect the following:

• Engine coolant performance

• Coolant leakage (engine internal, external)

• Water and anti-freeze mixture

• Thermostat (not fully open)

• Radiator (clogging)

• Fuses

• Is there any malfunction?

Yes

Service if necessary.

• Repeat this step.

No

Go to the next step.

8

• Inspect the engine coolant level.

  (See ENGINE COOLANT LEVEL INSPECTION [SKYACTIV-G 2.0].)

• Is there any malfunction?

Yes

Add engine coolant and verify that there is no engine coolant leakage.

(See ENGINE COOLANT REPLACEMENT [SKYACTIV-G 2.0].)

(See ENGINE COOLANT LEAKAGE INSPECTION [SKYACTIV-G 2.0].)

• If there is any malfunction:

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

No

Go to the next step.

9

• Verify the radiator hose tension.

  WARNING:

  • To prevent burns, use a cloth with your hand to verify the tension of the radiator hose.

• After the engine warms up, does the engine coolant circulate to the radiator hose?

Yes

Go to Step 11.

No

Go to the next step.

10

• Inspect the thermostat.

  (See THERMOSTAT INSPECTION [SKYACTIV-G 2.0].)

• Is the thermostat normal?

Yes

Inspect the water pump.

• If there is any malfunction:

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

  (See WATER PUMP REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

No

Replace the thermostat.

(See THERMOSTAT REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

11

• Inspect the drive belt.

  (See DRIVE BELT INSPECTION [SKYACTIV-G 2.0].)

• Is the indicator mark on the drive belt auto tensioner within the normal range?

Yes

Go to the next step.

No

Replace the drive belt.

(See DRIVE BELT REMOVAL/INSTALLATION [SKYACTIV-G 2.0].)

12

• Inspect for clogging in the radiator.

• Is there any malfunction?

Yes

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

No

Replace the engine coolant.

(See ENGINE COOLANT REPLACEMENT [SKYACTIV-G 2.0].)

13

Verify the test results.

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

  (See SYMPTOM DIAGNOSTIC INDEX [SKYACTIV-G 2.0].)

• 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.