1. Thermostat cover. 3. Thermostat. 5. Gasket. 2. Gasket. 4. Thermostat housing. 6. Water pump.
The thermostat opens a large circle of coolant circulation with an increase in engine temperature. If the thermostat remains closed due to a defect, the engine will become very hot. This is recognized by the readings of the temperature gauge, the readings of which are in the red area, while at the same time the radiator remains cold. A defective thermostat may also remain open after the coolant has cooled down. This is determined by the fact that the engine does not reach its operating temperature anymore or the temperature reading rises more slowly than before or the heater power is reduced in winter.
Attention! When the engine becomes hot after a short trip, the reason for this may be that deposits of scale have formed in the radiator.
Removing
Disconnect ground wire from battery.
Drain coolant.
Plug the hose on the cover of the thermostat housing.
Remove thermostat housing cover and set aside.
Remove the thermostat from the housing.
Examination
Hang the thermostat on a wire in a vessel of cold water. However, it should not touch the walls of the vessel. Control the temperature with a thermometer. At about 87°C (diesel engine - 80°С) the bimetal thermostat spring begins to stretch. The greatest stretch is achieved at 102°C (diesel engine - 94°С).
Check if the thermostat expands and closes back, otherwise replace it.
The thermostat at a given temperature should open approximately 6-8 mm.
Installation
Clean the mating surfaces of the body and cover.
Before installing, check whether the ball moves freely in the thermostat air vent valve.
Insert the thermostat with a new gasket into the housing.
The opening start temperature is pressed on the thermostat. When installing the thermostat element, pay attention to the free movement of the ball in the valve, as well as the position of the bleed valve on the main plate.
For 6-cylinder engines, it is installed at the bottom, for 8-cylinder engines - at the top.
Caution: Do not overtighten the bolts.
Screw on the bleed tube and, where necessary, secure with a clamp.
Fill with coolant.
Connect ground wire to battery.
Warm up the engine until the radiator connects. Check if the radiator is getting warm at the bottom and the tightness of the thermostat housing cover.