Hyundai Tucson Quiz
Engine Mechanical System

Thermostat

In this manual: Engine Mechanical System
General Information — 17Engine Mechanical System — 51Engine Electrical System — 26Emission Control System — 23Engine/Fuel Control System — 44Clutch System — 12MANUAL TRANSMISSION SYSTEM — 12AUTOMATIC TRANSMISSION SYSTEM — 42Four-Wheel Drive (4WD) System — 14Drive Shaft and Axle — 22Suspension System — 30Steering System — 16Restraint — 21Braking System — 47Body Work (Interior and Exterior) — 145Body Electrical System — 162Heating, Ventilation and Air Conditioning — 39
13steps
~78min
3/5difficulty
0102030405023.517N·mlb·ft
Tightening torque found on this page
Done 0 of 13

Components and Component Location

COMPONENTS

1. Water inlet connection
2. Thermostat		 3. Bypass hose
4. Heater hose and pipe assembly

Repair Procedures

Removal and Installation

  1. Drain the coolant so that its level is below the thermostat. (Refer to Cooling System – "Coolant".)
  2. Remove the lower radiator hose. (Refer to Cooling System – "Radiator Hose".)
  3. Remove the water inlet connection (A) and the thermostat (B).

    Tightening torque: 18.6~24 N·m

  4. Remove the intake manifold. (Refer to Exhaust and Intake System - "Intake Manifold")
  5. Remove the bypass hose (A).
  6. Loosen the heater pipe mounting bolts (B) and remove it.

    Torque: 19.6 ~ 24 N·m

  7. To install, perform the removal procedure in reverse order.
  8. Refill the engine coolant. (Refer to Cooling System – "Coolant".)
  9. Start the engine and check for leaks.
  10. Recheck the coolant level.

Inspection

  1. Immerse the thermostat in water and gradually heat the water.
  2. Check the valve opening temperature. If the valve opening temperature does not match the specified values, replace the thermostat. Valve opening temperature: 88 ± 1.5 °C Fully open temperature: 100 °C
  3. Check the valve lift. If the valve lift does not match the specified value, replace the thermostat.

    Valve lift: 8 mm (0.3 in) or more at 100 °C

Troubleshooting

TROUBLESHOOTING

Symptoms POSSIBLE CAUSES REMEDY
Coolant Leakage
  • From the thermostat gasket
 Check the mounting nuts.
  • Check the tightening torque of the mounting bolts.
  • Tighten the bolts and check for leaks again.
Make sure the seal is not damaged.
  • Check the gasket or seal for damage.
  • Replace the gaskets and reuse the thermostat.
Excessive cooling
  • Reduced heating performance (cold air is blown)
  • Temperature gauge indicates "LOW"
 Visually inspect after removing the radiator cap.
  • Insufficient coolant or leakage.
  • After refilling the coolant, check again.
GDS Check and Engine Start
  • Check the diagnostic trouble codes
  • Check the operation of the fan motor when the temperature changes.
  • Check the fan clutch connection or the fan motor.
※ If the fan clutch is still engaged, the engine will be slow to warm up.
  • Check the connectors, wiring, and engine coolant temperature sensor.
  • Check the fan motor, relay and connector.
  • Replace the components.
Remove the thermostat and check.
  • Check the thermostat valve for dust or debris.
  • Check the thermostat seating.
  • Clean the thermostat valve and reuse the thermostat.
  • Replace the thermostat if it does not operate properly.
Overheating
  • Engine Overheat
  • Temperature gauge indicates "HIGH"
 Visually inspect after removing the radiator cap.
  • Insufficient coolant or leakage. ※ Be careful when removing the radiator cap on an overheated vehicle.
  • Check for air in the cooling system.
  • After refilling the coolant, check again.
  • Check the cylinder head gaskets for damage and the tightening torque of the mounting bolts.
GDS Check and Engine Start
  • Check the diagnostic trouble codes
  • Check the operation of the fan motor when the temperature changes.
  • Check whether the fan clutch is slipping.
  • Check the water pump for seizure or impeller damage.
  • Check the connectors, wiring, and engine coolant temperature sensor.
  • Check the fan motor, relay and connector.
  • Replace the fan clutch if it does not operate properly.
  • Replace the water pump if it does not operate properly.
Immerse the thermostat in boiling water and check.
  • After removing the thermostat, check its operation.
※ Make sure the thermostat opens at the valve opening temperature.
  • Replace the thermostat if it does not operate properly.

Test yourself

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