Thermostat — check and replacement

A description of the thermostat pre-test is given in section «Cooling system - checking the technical condition». Removal of the thermostat is necessary if a malfunction is detected during a test on the vehicle or if there is a suspicion that the thermostat valve has not fully opened.

Sequence of execution on vehicles with 1.4 and 1.6 DOHC engines

1. We prepare the car for work (see «Preparing the car for maintenance and repair»).

2. Remove the engine trim (see «Decorative overlay of the engine - removal and installation»).

3. Drain the coolant (see «Coolant - replacement»).

4. We remove the coolant supply hose to the throttle assembly from the holders on the cylinder head cover (see «Cylinder head cover for 1.4 and 1.6 DOHC engines - removal, gasket replacement and installation»).

5. Using the TORX E8 key, we unscrew the three bolts securing the thermostat cover to the cylinder head.



6. Using a thin slotted screwdriver, pry...



... and remove the sealing ring of the thermostat cover, when assembling it must be replaced with a new one.




7. Slightly sinking, turn the thermostat...



... and remove it, disengaging it from the latches on the cover.



8. We place the thermostat in a container of water and start heating. When the temperature reaches 92°C, the thermostat should begin to open. At a temperature of 107°C, it should open completely, and its valve stroke should be about 7 mm. If the valve stroke is less or the thermostat fully open temperature is significantly less than specified, the thermostat must be replaced.


9. We install the parts in the reverse order.

10. Fill in the coolant (see «Coolant - replacement»).

Sequence of execution on vehicles with a 1.8 DOHC engine

1. We prepare the car for work (see «Preparing the car for maintenance and repair»).

2. Remove the engine trim (see «Decorative overlay of the engine - removal and installation»).

3. Drain the coolant (see «Coolant - replacement»).

4. Disconnect the coolant supply hose to the throttle assembly from the thermostat housing (see «1.8 DOHC engine cylinder head cover - removal, gasket replacement and installation»),

5. Disconnect the wiring harness block from the coolant temperature sensor (see «Coolant temperature sensor - check and replace»).

6. Using pliers, we loosen and move the clamp clamp along the hose...



... and disconnect the hose from the thermostat housing.



7. Using the TORX E8 key, unscrew the two bolts securing the thermostat housing to the cylinder head and remove it.




8. We place the thermostat in a container of water and start heating. When the temperature reaches 80°C, the thermostat should begin to open. At 107°C it should open completely. If the full opening temperature of the thermostat is significantly less than specified, the thermostat must be replaced.

9. We install the parts in the reverse order, be sure to replace the thermostat gasket with a new one.

10. Fill in the coolant (see «Coolant - replacement»).