Removing and checking the thermostat

The thermostat is removed only on a cold engine. Removing the thermostat is not particularly difficult, but if you are confident in your abilities, leave this work to a car repair shop. Remove the expansion tank cap to relieve pressure in the cooling system. Prepare the necessary spare parts and materials: thermostat, thermostat housing cover gasket, and heat-resistant sealant. Always change the gasket to ensure a good seal in the cooling system, as the cooling system is under pressure. Drain the leaked coolant into a clean container; after repair, it can be refilled into the reservoir.

A rough test of the thermostat's performance can be made using a glass vessel filled with water and a thermometer.

1. Remove the thermostat.

2. Hang the thermostat on a thread in a glass vessel filled with water and heat the water to a boil, while the thermostat should not touch the walls of the vessel.

3. Check if the thermostat valve opens and visually determine its movement.

4. The thermostat installed on the engines of the Omega car should begin to open at a temperature of 85-90°C and open completely at a temperature of 99-102°C.

5. A thermostat that does not close when the water is cold must be replaced.

WARNING

A thermostat that is stuck closed can cause the engine to overheat, causing the coolant to boil and its cooling effect to be insufficient to maintain the desired engine temperature. If this happens while driving, do not continue on any further journey. To avoid further damage, have the vehicle towed to the nearest workshop.


constant control



SEQUENCE OF WORK

1. To relieve pressure in the cooling system, open the cap of the expansion tank. Be careful when working on a hot engine - there is a risk of burns!

2. Place a clean container under the radiator and loosen the lower radiator hose clamp or unscrew the cap on the lower radiator tank. Drain approximately 3 liters of coolant.



Pic. 6.6. Thermostat connection elements: 1 - thermostat housing with hose connection; 2 – the top hose of a cooling liquid; 3 - hose going to the expansion tank

3. Loosen the hose clamp on the thermostat housing and remove the hose (pic. 6.6).



Pic. 6.7. The location of the thermostat housing on a 1.3 liter engine


4. Turn away bolts of fastening of the case of the thermostat and carefully remove the case. If the housing is tight, use a plastic or rubber mallet to knock it down with light blows (pic. 6.7).



Pic. 6.8. Fiesta car engine thermostat. The design of the thermostat on all engine versions is the same, only the opening temperatures of the thermostat valve differ

5. Thoroughly clean the mating surfaces, install the thermostat in the housing, while the arrow on the thermostat housing should be directed towards the radiator, apply a thin layer of sealant on both sides of the gasket and fix it on the flange (pic. 6.8).

6. Carefully place the cover on the housing, apply some sealant between the cover and the bolts, insert the bolts and tighten them evenly.

7. Attach the hose, fill the cooling system with the drained coolant and, if necessary, add fresh coolant.

8. Start up the engine and check up tightness of the cooling system. Install the plug on the expansion tank.