To have the conventional automobile engine cooling system graded up to an electronic control automobile engine cooling system.

Wall thickness in the sidewall of a center hole of an elastic seal spool 5 engaging with a rod 3 is extremely thinned, and further a jiggle valve mechanism is eliminated, boring at least one small hole in a flange surface of a thermostat, and a spring constant of a return spring 13 is halved, whereby an operating temperature range of the thermostat 1 is concentrated on a state changing area where wax 7 is liquefied from a solid body, and thus the upper limit of water temperature is lowered to less than 81°C by the interlocking of an electronic cooling fan switch. Subsequently, a flow rate of conventional cooling water is redoubled within the range of 50% in self-performance, and besides, adding an electronic control unit, an electronic control cooling system for an automobile engine is constituted in this way.