Kia Optima Hybrid: Cooling System / Thermostat Repair procedures

Kia Optima Hybrid (TF HEV) 2016-2020 Service Manual / Engine Mechanical System / Cooling System / Thermostat Repair procedures

Removal and Installation

Disassembly of the thermostat would have an adverse effect, causing a lowering of cooling efficiency. Do not remove the thermostat, even if the engine tends to overheat.

1.	Drain engine coolant so its level is below thermostat.

2.	Disconnect the radiator lower hose (A).

Remove water inlet fitting (C), gasket (B) and thermostat (A).

Tightening torque :

7.8 ~ 11.8N.m (0.8 ~ 1.2kgf.m, 5.8 ~ 8.7lb-ft)

4.	Installation is reverse order of removal.

•	Install the thermostat with the jiggle valve upward.

•	When assembling the thermostat, place the thermostat on the housing with a protrusion of thermostat matching with a groove of the housing and install the gasket and inlet fitting. Be careful the thermostat doesn’t get out of the groove on the housing.

1.	Fill the engine coolant.

2.	Start the engine and check for leaks.

3.	Recheck the coolant level.

Inspection

Immerse thermostat in water heated to over 95°C (203°F), then heat for at least 3 minutes to check valve lift.

•	Do not use water below 95°C (203°F).

•	Do not directly heat unit as this will damage thermostat.

Check the valve opening temperature.

Valve opening temperature: 88 ± 1.5°C (190.4 ± 34.7°F)

Full opening temperature: 100°C (212°F)

If the valve opening temperature is not as specified, replace the thermostat.

Check the valve lift.

Valve lift : 8mm (0.3in.) or more at 100°C (212°F)

If the valve lift is not as specified, replace the thermostat.

Water pump Troubleshooting

Troubleshooting SymptomsPossible CausesRemedyCoolant leakage • From the bleed hole of the water pump Visually check • Check leaks after about ten-minute warming up. • If coolant still leaks, replace ...

Thermostat Troubleshooting

Troubleshooting SymptomsPossible CausesRemedyCoolant leakage • From the thermostat gasket Check the mounting bolts • Check the torque of the mounting bolts • Retighten the bolts and check leakage ...

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