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5.3.1. Excessive pressure and fan of a radiator

Fig. 4.41. Check of a cover of a broad tank: 1 – cover of a broad tank; 2 – pump

The cooling system is under pressure. Thereby, and also thanks to antifreeze additive the boiling point of cooling liquid raises to +126 °C. More high temperature promotes more economic operation of the engine. Excessive pressure in the cooling system makes about 1,4-1,5 bars. If at the heated engine pressure increases up to the bigger size, the reducing valve of a broad tank in a cover (fig. 4.41) works. At an overheat the fan in addition turns on.
Engines are equipped or the fan with viskomufty, or the electric fan. These units turn on from a bimetallic thermoswitch in case temperature of the proceeding liquid exceeds a certain value. The switch switches-off the fan when temperature of cooling liquid falls to safe level.

The electric fan of a radiator can turn on also at the switched-off ignition because of aerodynamic heating of the engine.

Cooling system knots
Water pump. The centrifugal pump providing circulation of cooling liquid. At the 4-cylinder engine the water pump is on the same to a shaft, as the fan. At the 6-cylinder engine the water pump is installed on the left side of the engine on 4 bolts.
Radiator. All radiators are made of light alloy. Radiators, as well as a fan casing, have various dimensions. At cars with the automatic transmission at the right water tank of a radiator the crane of discharge of cooling liquid is installed.
Thermostat. This regulator depending on temperature operates contours of circulation of cooling liquid.
Contour at a temperature up to +85 °C: cooling liquid circulates on a small contour.
Contour of normal work at temperatures of +85... +100 °C: partially the radiator opens; cold liquid from a radiator mixes up with warm cooling liquid before she the pump moves in the engine.
The maximum cooling at a temperature above +100 °C: the valve of the thermostat is completely open, all cooling liquid passes through a radiator.
Broad tank. Pits steam at emergence of excessive pressure via the reducing valve in a cover.
Radiator fan. Depending on the engine, and also from equipment of the car, the fan with viskomufty or the electric fan is installed.

   Additional fan
If on your car the conditioner is installed, then before a radiator are established two connected with each other by means of a fan belt, and the fan located at the left is supplied with an electric motor from which the right fan also works.