NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZI-3.7]

id0103d2802300

17 | COOLING SYSTEM CONCERNS—OVERHEATING
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DESCRIPTION | • Engine runs at higher than normal temperature/overheats.
POSSIBLE CAUSE | • Improper coolant level • Coolant leakage • Improper water/anti-freeze mixture • Poor radiator condition • Radiator hoses damage • Improper or damaged radiator cap • Coolant overflow system malfunction • Fans reverse rotation • Blown cooling fan control related fuses • PCM DTC is stored. • Excessive A/C system pressure • A/C system operation is improper. • Cooling fan is inoperative. • Improper tension of drive belt • Drive belt damage • Coolant leakage from climate control unit • Improper water temperature gauge operation ― CHT sensor malfunction ― Instrument cluster malfunction • Thermostat malfunction • Cylinder block or cylinder head malfunction (cracked, coolant restriction)

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Inspect the following: • Engine coolant level • Coolant leakage • Water and anti-freeze mixture • Radiator condition • Collapsed or restricted radiator hoses • Radiator pressure cap • Overflow system • Fan rotational direction • Fuses Are all items normal? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part according to the inspection results. Repeat Step 1.
2 | Turn the ignition switch to the ON position (Engine off). Retrieve any PCM DTCs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7].) Are there any DTCs displayed? | Yes | DTC is displayed: • Go to the appropriate DTC inspection. (See DTC TABLE [MZI-3.7].)
No | No DTC is displayed: • Go to the next step.
3 | Start the engine and idle it. Turn the A/C switch on and set blower fan to any speed by switching the control panel. Does the A/C compressor engage/disengage according to control panel switching? | Yes | Go to the next step.
No | If the A/C compressor is not engaged always: • Go to the symptom troubleshooting “NO.23 A/C DOES NOT WORK SUFFICIENTLY”. (See NO.23 A/C DOES NOT WORK SUFFICIENTLY [MZI-3.7].) If the A/C compressor is engaged always: • Go to 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 [MZI-3.7].)
4 | Inspect the cooling fan control system operation. (See ENGINE CONTROL SYSTEM OPERATION INSPECTION [MZI-3.7].) Does the cooling fan control system function properly? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part according to the inspection results.
5 | Inspect the drive belt. (See DRIVE BELT INSPECTION [MZI-3.7].) Is the drive belt normal? | Yes | Go to the next step.
No | Replace the drive belt. (See DRIVE BELT REMOVAL/INSTALLATION [MZI-3.7].)
6 | Is there leakage around the climate control unit in passenger compartment? | Yes | Inspect the heater for leakage. Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
7 | Is there leakage at the coolant hoses and/or radiator? | Yes | Repair or replace the malfunctioning part according to the inspection results.
No | Go to the next step.
8 | Access and monitor the PCM PID ECT using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7].) Compare the ECT PID and water temperature gauge on instrument cluster reading. Is the ECT PID reading is same as water temperature gauge reading? | Yes | Go to the next step.
No | Inspect the water temperature gauge. (See INSTRUMENT CLUSTER INSPECTION.) Repair or replace the malfunctioning part according to the inspection results. • If the water temperature gauge reading is normal, inspect the CHT sensor. (See CYLINDER HEAD TEMPERATURE (CHT) SENSOR INSPECTION [MZI-3.7].) • Repair or replace the malfunctioning part according to the inspection results.
9 | Cool down the engine. Remove the thermostat and inspect the operation. (See THERMOSTAT REMOVAL/INSTALLATION [MZI-3.7].) (See THERMOSTAT INSPECTION [MZI-3.7].) Is the thermostat normal? | Yes | Engine coolant temperature and thermostat are normal, inspect engine block for leakage or blockage. Repair or replace the malfunctioning part according to the inspection results.
No | Replace the thermostat. (See THERMOSTAT REMOVAL/INSTALLATION [MZI-3.7].)
10 | • Verify test results. ― If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7].) ― If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle is repaired, troubleshooting completed. • If vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZI-3.7].)