In addition to supplying the circuit, the coolant reservoir absorbs the variations in the volume of the coolant as the temperature of the engine varies.A special calibrated valve in the pressurised cap assures the following:- escape of air from the circuit collected by the pipe coming from the thermostat- air intake when the circuit contains a vacuum (due to engine cooling).
ENGINE COOLING RADIATOR
It consists of a radiant mass and two side tanks for the intake and outlet of coolant.The radiator pipes and fins are aluminium, the tanks are plastic.