Contents: Replacement ⇓ Checking the Thermostat ⇓
Caution! Replace the thermostat on a cold engine. In addition, when carrying out any work near the fan, to prevent it from turning on accidentally, it is necessary to disconnect the wire from the negative terminal of the battery.
Replacement
Please read the warnings provided in section 2.
Disconnect the cable from the negative terminal of the battery (if this has not been done previously).
To make it easier to access the thermostat housing, remove the ignition distributor.
Drain the coolant from the cooling system to a level corresponding to the lower edge of the thermostat. To do this, unscrew the radiator filler cap and the drain plug at the bottom. After draining a sufficient amount of coolant, screw in the drain plug.
Disconnect the upper radiator hose from the thermostat housing outlet pipe.
Figure 5.1. Cooling system elements: 1 – expansion tank; 2 – toothed belt; 3 – water pump; 4 – radiator filler cap; 5 – bypass hose; 6 – radiator fan motor; 7 – radiator; 8 – fan relay; 9 – thermostat; 10 – fan thermal switch
Unscrew the thermal switch of the cooling system fan (figure 5.1).
Unscrew the two nuts and remove the thermostat housing from the engine. You can use a rubber hammer to loosen the hardened gasket that is making it difficult to remove the thermostat housing.
Figure 5.2. Thermostat mounting elements: 1 – upper radiator hose; 2 – thermostat housing; 3 – gasket; 4 – thermostat; A – pin (when installing the thermostat, it should be facing upwards)
Mark the position and remove the thermostat from the housing (figure 5.2).
Before installing the thermostat, clean the surface of the exhaust pipe and the mating surface of the thermostat housing from any remaining gasket.
Apply a thin layer of sealant to both sides of the new gasket.
Install the thermostat into the housing and position the gasket so that the ribbed surface faces the thermostat. Install the cover and secure with bolts, tightening them to the required torque.
Place a hose onto the thermostat housing outlet pipe and secure it securely with a clamp. Make sure the arrow on the hose is aligned with the protrusion on the body.
Screw in the radiator fan thermal switch.
Install the ignition distributor.
Fill the cooling system with antifreeze of the appropriate concentration.
Connect the cable to the negative terminal of the battery and start the engine.
Let the engine run with the filler cap removed until the upper radiator hose becomes hot (the thermostat is open).
With the engine idling, add coolant to the radiator to the bottom of the filler neck.
Install the filler cap.
Checking the Thermostat
It is best to check the thermostat after it has been removed from the engine. As a rule, if you suspect a malfunction, it is most advisable to replace the thermostat, since its cost is low.
To check, remove the thermostat.
If there are signs of severe corrosion or damage, the thermostat must be replaced.
(Based on website data: «MAZBOOK.RU»)
To test the thermostat's functionality, hang it on a thread in a glass vessel filled with water and heat the water to boiling point, making sure the thermostat does not touch the walls of the vessel. Monitor the water temperature with a thermometer. The thermostat should begin to open at 88°C and should be fully open at 97°C. Otherwise, replace it.
A thermostat that does not close when the water cools also needs to be replaced.
Install the thermostat.