The cooling system consists of a cooling jacket (inside the cylinder block and head), radiator, water pump, thermostat, cooling fan, viscous coupling, hoses and other components.
The coolant heated in the cooling jacket is sent to the radiator, where it is cooled by the air supplied by the fan. From the radiator, the coolant is pumped back to the engine by a water pump to cool it.
The cooling jacket is a network of channels in the cylinder block and block head through which the coolant passes.
The radiator is installed in front of the car. It consists of upper and lower tanks connected by a core (with heat exchange surfaces). The upper tank has an inlet pipe, a filler neck and a hose through which excess coolant and steam are removed from the radiator. The lower tank has an outlet pipe and a valve for draining the liquid.
The core of the radiator consists of many tubes through which liquid flows from the upper tank to the lower one, as well as fins through which heat is removed from the liquid in the tubes. The radiator is cooled by the airflow generated by the fan.
Models with automatic transmission are equipped with a heat exchanger for cooling the working fluid, installed in the lower radiator tank.
The radiator cap hermetically closes the radiator, maintaining pressure inside it. The pressurized operation of the system prevents the coolant from boiling even when the temperature of the latter exceeds 100°C. The radiator cap has two safety valves - steam and air. Steam valve opens to remove steam through the outlet pipe (hose), when the pressure inside the cooling system exceeds the maximum allowable (coolant temperature 110-120°C, pressure 63.7-103.0 kPa). The air valve opens to reduce the vacuum that occurs in the cooling system after the engine has stopped and the temperature has dropped. Opening the valve allows the coolant to return to the system from the expansion tank.
Excess coolant enters the expansion tank, as a result of an increase in the volume of the latter when it is heated in the cooling system. The liquid from the expansion tank returns to the radiator when the temperature in the system drops, as a result of which the radiator is always filled with liquid and at the same time liquid losses are eliminated. You should check the coolant level in the expansion tank and add it in time.
The water pump circulates the coolant in the cooling system. The pump is installed at the front of the cylinder block and is driven by a V-belt. The thermostat is installed in the inlet water pipe of the radiator. The solid fill inside the thermostat expands when heated and contracts when cooled. Thus, when the wax filler is heated, a pressure force arises that overcomes the resistance of the spring, which tends to keep the valve in the closed position, and the valve opens. The thermostat opens at a temperature of 82-88°C. When the filler cools, the spring closes the valve.
Engine cooling system (L-series): 1 - thermostat housing, 2 - thermostat, 3 - oil-water radiator, 4 - branch pipe, 5 - water pump.
Engine cooling system 1KZ-T: 1 - radiator, 2 - thermostat, 3 - oil cooler.
Direction of coolant flow