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

id0103d2802300

17

COOLING SYSTEM CONCERNS—OVERHEATING

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)

17	COOLING SYSTEM CONCERNS—OVERHEATING
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
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.
1		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 (PCM CONNECTOR (2 TYPES))].) (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7 (PCM CONNECTOR (3 TYPES))].) Are there any DTCs displayed?	Yes	DTC is displayed: • Go to the appropriate DTC inspection. (See DTC TABLE [MZI-3.7 (PCM CONNECTOR (2 TYPES))].) (See DTC TABLE [MZI-3.7 (PCM CONNECTOR (3 TYPES))].)
2		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.
3		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.
4		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.
5		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.
6		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.
7	Is there leakage at the coolant hoses and/or radiator?	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 (PCM CONNECTOR (2 TYPES))].) (See ON-BOARD DIAGNOSTIC TEST [MZI-3.7 (PCM CONNECTOR (3 TYPES))].) 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.
8		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.
9		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].)