Tube-ribbon radiator, with oval tubes, four-row

The radiator filler cap (Fig. 1) is sealed with two valves; inlet (air) and outlet (steam)

A spring-loaded exhaust valve maintains a pressure of 1 kg/cm2 in the cooling system.

At this pressure, the coolant boils at a temperature of 119˚ C

Consequently, a reserve of efficiency of the cooling system is created and the car can be operated in difficult conditions for a longer time with non-boiling water in the radiator.

If the rubber washers 6 and 11 of the radiator cap valves are missing or destroyed, then the operation of the cooling system as a closed system stops, and the liquid boils in this case at 100˚ C.

ZIL-131 Radiator Plug

The inlet valve, loaded with a weaker spring, prevents the creation of a large vacuum in the system when the engine cools down and protects the radiator parts from damage.

The inlet valve opens and communicates the radiator cavity with the atmosphere when the pressure drops by 0.01-0.13 kg / cm.

The temperature of the coolant in the cooling system is controlled by a gauge mounted on the instrument panel.

The temperature gauge sensor is located in the water channel of the engine intake pipe.

When the coolant temperature reaches 115° C, the control lamp for emergency overheating of the coolant, the sensor of which is located in the upper radiator tank, lights up on the instrument panel

In this case, open the cap of the radiator or expansion tank carefully, as if the cap is suddenly opened, hot water may be ejected from the neck.

ZIL-131 thermostat operation scheme

The thermostat with solid fill is placed between the upper and lower water jacket pipes.

The thermostat is used to accelerate the warm-up of a cold engine and protect it from hypothermia.

When a cold engine warms up, the channel connecting the engine jacket to the radiator is blocked by thermostat shutter 7 (Fig. 2).

The coolant circulates intensively through the bypass pipe connecting the lower outlet pipe of the water jacket with the suction cavity of the water pump bearing housing, bypassing the radiator, which accelerates engine warm-up.

This circulation is maintained until the thermostat is fully open.

When the coolant reaches a temperature of 70-83 ° C, ceresin (petroleum wax) 2 (Fig. 2, b), enclosed in a thermostat bottle 1, melts and, increasing its volume, causes the rod 5 to move upwards and opens the damper 7, after which the coolant begins to circulate through the radiator.

When the temperature drops, ceresin reduces its volume, and the damper closes under the influence of a spring (Fig. 2, a).

The radiator louvers are used to control the flow of air passing through the radiator; blinds are controlled from the driver's cab.

The control stick is located under the shield on the left side of the cab. To close the blinds, pull the handle towards you.

Blinds should be closed when the engine is warming up, as well as when driving in case of a drop in coolant temperature.