Coolant pump
centrifugal type (pic. 20), body 1 and cover 2 made of aluminum alloy. The bearing 10 in the cover is locked with a screw 9. The bearing is double-row, non-separable, without an inner cage, sealed with washers 6. The impeller 12 and the hub 5 of the pulley 8 of the fan drive 4 and the pump are pressed onto the shaft 7. To the end face of the impeller, hardened by high-frequency currents to a depth of 3 mm, the sealing ring made of graphite composition is pressed. The seal 11 of the pump is non-separable, it is pressed into the pump cover. The latter is attached to the pump housing with nuts 3.
Fan
Four-bladed, plastic fan 11 (see fig. 19) is installed in the casing 10 and fastened with three bolts to the pump shaft hub together with the drive pulley 13. The fan is driven from the crankshaft pulley by a V-belt 15.
Radiator and expansion tank
The radiator 9 is mounted on two rubber cushions 12 and is attached to the front end of the body with four bolts. Consisting of top and bottom tanks, two rows of tubes and tinned cooling plates. The filler neck of the radiator is closed with a plug 8 and connected with a hose to the expansion tank 6.
The radiator cap has inlet and outlet valves through which the radiator is connected by a hose to the expansion tank. Inlet valve is not pressed against the gasket (clearance 0.5-1.1 mm) and allows the inlet and outlet of fluid into the expansion tank during heating and cooling. The liquid enters the heater radiator from the cylinder head through hose 2, and returns through hose 1.
Operation of the cooling system
When the coolant temperature is below 80°C, the main thermostat valve is closed and the bypass valve is open. The coolant circulates from the cooling jacket 7 through the branch pipe 4 along the bypass hose 3, through the thermostat bypass valve and hose 17 to the pump 16 and further to the cooling jacket (in a small circle), bypassing the radiator 9. This provides a quick warm-up of the engine.
If the liquid temperature is above 94°C, the liquid circulates in a large circle: from the cooling jacket through the hose 5, radiator, hose 14, thermostat 18 and the pump enters the cooling jacket.
In the temperature range of 80–94°C, the liquid circulates both in large and small circles (thermostat valves are in an intermediate position). An increase in the degree of opening of the main valve provides a gradual mixing of the liquid cooled in the radiator and maintains the best thermal regime of the engine.
When the liquid boils or the temperature rises sharply, the liquid does not have time to pass through the inlet valve of the filler plug into the expansion tank and closes it, separating the system from the expansion tank. In this case, the pressure can increase up to 0.5 kgf / cm2, until the exhaust valve opens and some of the coolant flows into the expansion tank. The tank is closed with a stopper with a rubber valve that operates at a pressure close to atmospheric.