The coolant pump is a vane, centrifugal type, driven from the crankshaft pulley by a V-belt. The pump casing is aluminium. The roller rotates in a double row bearing with a lifetime supply of grease. The outer ring of the bearing is locked with a screw. A pulley hub is pressed onto the front end of the roller, and a plastic impeller is pressed onto the rear end. For the correct position of the pump pulley groove, the distance from the mating surface of the pump cover to the outer end of the hub must be 84.4±0.1 mm. When installing a cover with a gasket, they also check the gap of 0.9–1.3 mm between the impeller blades and the pump housing. To do this, you can use plasticine rollers: they are placed on equidistant impeller blades, a cover is installed, its fastening nuts are tightened, then the cover is removed and the remaining plasticine thickness is measured - it is equal to the gap.
Axial and radial play in the pump bearing, which can be felt by hand, is not allowed. In case of failure of the bearing or self-locking stuffing box of the pump, it is recommended to replace the pump cover assembly with the shaft and impeller.
The redistribution of fluid flows is controlled by a thermostat with a solid temperature-sensitive element. On a cold engine, the thermostat valve closes the pipe leading to the radiator, and the liquid circulates only in a small circle (through the thermostat bypass), bypassing the radiator. The small circle includes the heater radiator, intake manifold, carburetor heating block (on engine 21213) or throttle assembly (on engine 21214). At a temperature of 78–85°С, the valve begins to move, opening the main branch pipe; in this case, part of the liquid circulates in a large circle, through the radiator. At a temperature of about 90°C, the main valve opens completely, and the bypass valve closes, and all the liquid circulates through the engine radiator. The main valve stroke must be at least 6.0 mm.
You can assess the health of the thermostat by heating the lower radiator pipe: it should be cold until the temperature of the liquid (by index) will not reach 80–85°C, and hot when it rises to 85–90°C. The thermostat is not repairable. In case of malfunction, loss of tightness, deformation of the nozzles, it is replaced.
The radiator consists of two vertical plastic tanks (left - with a partition) and two horizontal rows of round aluminum tubes with pressed-on cooling plates. To increase the cooling efficiency, the plates are stamped with a notch. The tubes are connected to the tanks through a rubber gasket. Fluid enters through the top port and exits through the bottom port. At the bottom of the left tank is a plug for draining the coolant.
For better airflow to the radiator, casings are designed to direct air flows from the fan (fans). On the 21213 engine, the main fan shroud consists of two halves (bottom and top), the lower half has a rubber seal on the radiator side. An additional guide casing is installed in front of the radiator. On the 21214 engine, the electric fans rotate in a casing in front of the radiator.
The expansion tank is made of translucent polyethylene, which allows you to visually control the liquid level (3–5 cm above the mark «MIN» on a cold engine).
To control the temperature of the coolant, a sensor is screwed into the engine cylinder head, connected to the temperature gauge on the dashboard. An additional temperature sensor is installed in the exhaust pipe of the engine 21214, which provides information to the electronic engine control unit (see Injection engine control system).
The heating system is described in chapter Heating and ventilation system.