Removing the thermostat (Peugeot Eurovans 806)

To remove the thermostat, it is necessary to drain the coolant from the system and disconnect the hoses from the fittings by loosening the fastening clamps. One hose leads to the oil cooler (if one is installed), and the second - to the lower radiator pipe.

1. Turn out bolts of fastening of a cover of the case of the thermostat and take the thermostat. The thermostat housing cover has a rubber o-ring (see illustration).



The thermostat cannot be repaired and is replaced with a new one in case of a defect. Checking the thermostat is quite simple.

2. Attach the thermostat to the wire and lower it into a container of cold water. Attach the thermometer to the container in the same way. The thermostat and thermometer must not touch the walls of the container.


3. Heat the water in the tank and see if the thermostat starts to open when the water is heated to the thermostat opening temperature. When the water is heated to a certain temperature, the thermostat should open completely. The thermostat opening temperature is specified in the specifications. The opening stroke of the thermostat is at least 7.5 mm. If the thermostat fails the specified test, it must be replaced.

When installing the thermostat, the old sealing gasket is replaced with a new one. For good sealing of surfaces, it is recommended to apply a sealing mass to them (sealant).

4. Check up collars by which hoses of a cooling liquid fasten. Replace clamps if necessary.

5. Fill the system with coolant.

If a new thermostat has been installed, carry out a test drive to verify that the thermostat is functioning properly.

The thermostat may not open as a result of jamming or sticking. This defect manifests itself in the fact that the arrow of the coolant temperature gauge has long «going off scale», and the indicator light is on, but the radiator is still cold.

6. Stop the engine and let it cool down. After that, disconnect open the thermostat cover and remove the thermostat. Driving without a thermostat will not affect the engine. Driving with the thermostat not opening can cause significant engine damage. The cylinder head gasket may burn out, and the head itself may «stories» or it may crack.

The thermostat may not close completely as a result of foreign particles getting into it. In this case, immediately after starting the engine, the radiator heats up, as does the thermostat housing. Interior heating is very slow.

7. Replace the thermostat as soon as possible, because it reduces the economy of the car, and in addition, it will damage the engine.