To check the thermostat on your car, start the engine and touch the lower radiator hose with your hand - it should be cold. Once the coolant temperature reaches 85-92°C, the hose should begin to heat up. If this does not happen, remove the thermostat and check its functionality.
You will need: a 5 mm Allen key and a Phillips-head screwdriver.
1. Remove the cap from the expansion tank. Unscrew the drain plug at the bottom of the right radiator tank and drain the fluid from it (see "Replacing the coolant"). Screw the drain plug back on.
2. Loosen the two hose clamps on the thermostat cover pipes...
3. ...and remove the hoses from the cover pipes.
4. Remove the three cover mounting bolts...
5. ...and remove it together with the thermostat.
Note: Pay attention to the condition of the sealing rubber ring in the groove of the thermostat cover. Replace a severely deformed, torn or loose ring.
6. Overcoming the force of the spring, press the thermostat retaining plate down and, turning it in any direction, disengage it from the grooves.
7. Remove the thermostat from the cover.
8. Before installing a new thermostat, test it by placing it in water heated to 78–80°C. Heat the water, stirring constantly, to a temperature of (85±2)°C.
9. At a temperature of (85±2)°C the thermostat rod should begin to extend from the power element. If this does not happen, replace the thermostat.
10. Install the thermostat in the reverse order of removal.
Note: To prevent future coolant leaks, apply a thin layer of sealant to the thermostat cover fittings before connecting the hoses to the thermostat cover.
11. Fill the cooling system with liquid (see "Replacing the coolant"). Tighten the expansion tank cap, start the engine, check for coolant leaks through the thermostat hose connections and warm up the engine at idle speed to operating temperature to remove air locks from the system.