Replacing the thermostat
We remove the battery.
Drain the liquid from the engine cooling system (see Replacing the coolant).
It is more convenient to remove the thermostat together with the upper hoses.
We loosen the clamps and disconnect the upper thermostat hose from the cylinder head pipe...
...and the middle hose from the coolant pump pipe.
We disconnect the lower hose either from the thermostat itself...
...or from the lower radiator hose (see Engine Radiator Replacement).
We remove the thermostat.
The original can be found on the website: VazBook
Disconnect the hoses from the thermostat housing.
Checking the Thermostat
To check the thermostat, lower it into a container with coolant. Lower the thermometer there and heat the liquid to boiling. The upper part of the thermostat should be completely closed (bypass) valve and the lower (main) valve should open and remain in this position at a temperature of 82–87°C. As the liquid cools, the upper valve should gradually open and the lower one should close.
We install the thermostat in the reverse order of removal.