Attention! Replace the thermostat on a cold engine. In addition, when carrying out any work near the fan, to prevent its arbitrary activation, it is necessary to disconnect the wire from the negative terminal of the battery.
Replacement
Read the warnings in sec. 2.
Disconnect the wire from the negative battery terminal (if not done before).
To facilitate access to 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 filler cap of the radiator and the drain plug at its bottom. After draining a sufficient amount of coolant, screw in the drain plug.
Disconnect the upper radiator hose from the outlet pipe of the thermostat housing.
Pic. 5.1. Elements of the cooling system: 1 - expansion tank; 2 - toothed belt; 3 - water pump; 4 – a stopper of a bulk mouth of a radiator; 5 - bypass hose; 6 - radiator fan motor; 7 - radiator; 8 - relay for turning on the fan; 9 - thermostat; 10 - fan thermal switch
Turn out the thermal switch of the fan of system of cooling (pic. 5.1).
Remove the two nuts and remove the thermostat housing from the engine. You can use a rubber mallet to loosen the hardened gasket that makes it difficult to remove the thermostat housing.
Pic. 5.2. Thermostat mounting elements: 1 – the top hose of a radiator; 2 - thermostat housing; 3 - gasket; 4 - thermostat; A - pin (when installing the thermostat, it must be directed upwards)
Mark the position and remove the thermostat from the housing (pic. 5.2).
Before installing the thermostat, clean the surface of the exhaust pipe and the mating surface of the thermostat housing from the remnants of the gasket.
Apply a thin coat of sealant to both sides of the new gasket.
Install the thermostat into the housing and position the gasket so that the serrated surface faces the thermostat. Install the cover and secure with bolts, tightening them to the required torque.
Put a hose on the outlet pipe of the thermostat housing and secure it securely with a clamp. Make sure the arrow on the hose lines up with the tab on the housing.
Screw in the radiator fan thermal switch.
Install the ignition distributor.
Pour antifreeze of the appropriate concentration into the cooling system.
Connect the wire to the negative battery terminal and start the engine.
Run the engine with the filler cap removed until the top radiator hose is hot (thermostat open).
While the engine is idling, add coolant to the radiator up to the bottom of the filler neck.
Install the filler cap.
Thermostat check
It is best to check the thermostat after removing it from the engine. As a rule, if a malfunction is suspected, the thermostat is most advisable to replace, since its cost is low.
Remove the thermostat to check.
If there are signs of severe corrosion and damage, the thermostat must be replaced.
To check the functionality of the thermostat, hang it 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. Check the water temperature with a thermometer. The thermostat should begin to open at 88°C and open fully at 97°C. Otherwise, replace it.
A thermostat that does not close when the water cools should also be replaced.
Install thermostat.