ENGINE COOLER

PURPOSE:To improve the heating effect of a heater by automatically changing the cooling water temperature applied to a heater from an engine internal water channel when the heater is actuated to the high temperature side. CONSTITUTION:In a cooling system in which the cooling water of a radiator 2 is sent to the internal water channel of an engine 1 from a wate pump 4 and is returned to the radiator 2 from a cooling water 7 through a thermo valve 5, a heat radiation type heater 10 for heating is provided and comparatively high temperature cooling water is guided to the heater from a heater passage 11. On the other hand, a valve 12 which can be opened and closed by an operator is provided above the heater 10 of the heater passage 11. Besides, the lower passage than the heater 10 of the heater passage 11 is inseted crossly in the immediate upper part of the thermo valve 5 of the passage 7 mentioned above. Moreover, a heat exchanger 20 is provided at this heater passage insertion section and a heater passage 11a passing through the heat exchanger 20 is merged into a bypass passage 8.