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 connection of the fan clutch or the fan motor. |
x If the fan clutch is always connected, there will be a noise at idle.
|
| • |
Check the engine coolant sensor, wiring and connectors. |
| • |
Replace the componants. |
|
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
|
| • |
Thermogauge indicates 'HI' |
| Visually check after removing the radiator cap.
|
| • |
Insufficient coolant or leakage.
x 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 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. |
x Check the thermostat opens at the valve opening temperature.
|
| • |
Replace the thermostat, if it doesn't work properly. |
|
Hyundai Equus: Thermostat Troubleshooting
Second generation VI (2009–2025) / Hyundai Equus VI 2009-2025 Service Manual / Engine Mechanical System / Cooling System / Thermostat Troubleshooting
Thermostat Repair procedures
