Hyundai Sonata: Thermostat Troubleshooting - Cooling System - Engine Mechanical SystemHyundai Sonata: Thermostat Troubleshooting

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)
Temperature gauge 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 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
Engine overheated
Temperature gauge 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.

    Thermostat Repair procedures
    Removal     Disassembly of the thermostat would have an adverse effect, causing a lowering of cooling efficiency. 1. Drain engine coolant so that its level would be under the ...

    See also:

    Fuel Pressure Control Valve. Repair procedures
    Inspection 1. Turn the ignition switch OFF and disconnect the battery negative (-) cable. 2. Disconnect the fuel pressure regulator valve ...

    Recommended cold tire inflation pressures
    All tire pressures (including the spare) should be checked when the tires are cold. “Cold Tires” means the vehicle has not been driven for at least three hours or driven less than one mile (1. ...

    Shift Cable Components and Components Location
    Components 1. Shift lever knob2. Shift lever assembly3. Shift cable4. Shift cable retainer ...