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Home >> Hyundai >> 2017 >> Azera Base >> Repair and Diagnosis >> Engine Mechanical >> Cooling Fan >> Engine Cooling System >> Thermostat >> Troubleshooting

Engine Cooling System: Thermostat: Troubleshooting

Symptoms Possible Causes Remedy
Coolant leakage
  • From the thermostat gasket
Check the mounting bolts
  • Check the torque of the mounting bolts
  • Retighten the bolts and check leakage again.
Check the gasket for damage
  • Check gasket or seal for damage
  • Replace gaskets and reuse the thermostat.
Cooled excessively
  • Low heater performance (cool air blowed-out)
  • Thermogauge indicates "LOW"
Visually check after removing the radiator cap.
  • Insufficient coolant or leakage.
  • After refilling coolant, recheck.
GDS check & Starting engine
  • Check DTCs
  • Check connection of the fan clutch or the fan motor.
* If the fan clutch is always connected, there will be a noise at idle.
  • Check the engine coolant sensor, wiring and connectors.
  • Replace the components.
Remove the thermostat and inspect
  • Check if there are dusts or chips in the thermostat valve.
  • Check adherence of the thermostat.
  • Clean the thermostat valve and reuse the thermostat.
  • Replace the thermostat, if it doesn't work properly.
Heated excessively
  • Engine overheated
  • Thermogauge indicates "HI"
Visually check after removing the radiator cap.
  • Insufficient coolant or leakage.

    * Be careful when removing a radiator cap of the overheated vehicle.

  • Check air in cooling system.
  • After refilling coolant, recheck.
  • Check the cylinder head gaskets for damage and the tightening torque of the mounting bolts.
GDS check & Starting engine
  • Check DTCs
  • Check the fan motor performance as temperature varies.
  • Check if the fan clutch slips.
  • Check the water pump adherence or impeller damaged.
  • Check the engine coolant sensor, wiring and connectors.
  • Check the fan motor, the relay and the connector.
  • Replace the fan clutch, if it doesn't work properly.
  • Replace the water pump, if it doesn't work properly.
Immerse the thermostat in boiling water and inspection.
  • After removing the thermostat, check it works properly.

    * Check the thermostat opens at the valve opening temperature.

  • Replace the thermostat, if it doesn't work properly.