Thermostat — Removal, Installation and Checking (Renault Scenic 1)

As the engine temperature increases, the thermostat opens a large circuit of coolant circulation. If, due to a malfunction, the thermostat does not work, the engine will overheat. This situation is signaled by the coolant temperature control lamp on the instrument panel. At the same time, the radiator remains cold. A faulty thermostat may remain open after the coolant has cooled. This thermostat defect can be determined by the fact that the engine does not warm up to operating temperature. If such a thermostat defect occurs in winter, the intensity of the interior heating decreases.

Attention! If the engine overheats after a short mileage, the cause may be limescale deposits clogging the radiator, or a broken V-belt of the water pump drive.

Removal

1. Disconnect the negative (-) battery terminal.

Warning! This will delete data from the memory devices, such as the radio receiver security code. Before disconnecting the battery, read the recommendations in the chapter "Battery - Removal and Installation".

2. Drain the coolant into a suitable container.

3. Remove cover 1 of the thermostat housing by unscrewing the mounting bolts (see illustrations 6.3 and 6.3a).







4. Record the installation position of thermostat 11 in the coolant pipe and remove it (see illustration).

Examination

5. Measure the height of the thermostat and record it as value a (see illustration).





6. Heat the thermostat in a container with water. The thermostat should not touch the walls of the container and should be completely immersed in water. Check the water temperature with an appropriate thermometer (see illustration).



Once the water temperature reaches approximately +89°C, the thermostat valve will begin to open.

The greatest stroke of the thermostat valve occurs at a temperature of approximately +101°C. At this water temperature, the valve should open completely. This means that its stroke should be at least 7.5 mm. To determine the stroke of the thermostat valve, it is necessary to subtract the value a from the value b (see illustration 6.5).

Attention! Since the thermostat opens completely when the water temperature exceeds its boiling point, the data provided should be considered as approximate.

7. Make sure that the thermostat valve closes when cooling down. If not, replace the thermostat.

Installation

8. Install the thermostat into the outlet pipe.

9. Cars with a 1.4-/1.6-liter gasoline engine (K7J/K7M). Clean the sealing surfaces on the cylinder head and thermostat housing. Apply sealant to these surfaces "LOCTITE 518" the layer of sealant H should be between 0.6 and 1.0 mm and it should be applied as shown in the illustration.





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10. Cars with 2.0 litre petrol engine and 1.9 litre diesel engine: Secure the thermostat cover by replacing its old rubber gasket with a new one.

11. Connect the negative (-) terminal of the battery cable to the negative terminal.

12. Set the clock.

13. Enter the code into the radio receiver if necessary.

14. Fill the coolant and bleed air from the cooling system.