Engine water-cooling device

An engine water-cooling device comprising:

• an intra-head cooling water jacket in a cylinder head;
• a thermostat;
• a bypass passage;
• a radiator;
• and a cooling water pump, and
• configured such that engine cooling water in the intra-head cooling water jacket flows back to the cooling water pump via the bypass passage bypassing the radiator and when a water temperature of the engine cooling water detected by the thermostat exceeds a predetermined value, the thermostat causes the engine cooling water in the intra-head cooling water jacket to flow back to the cooling water pump via the radiator,
• wherein the engine water-cooling device includes a thermostat housing that houses the thermostat, the thermostat housing is mounted to a front wall of the cylinder head in one side portion in a width direction of the cylinder head, the cooling water pump is mounted to a front wall of a cylinder block in a central portion in a width direction of the cylinder block,
• the bypass passage includes an intra-head bypass passage in the cylinder head, and the intra-head bypass passage includes a width-direction passage portion extending from a position behind the thermostat housing to a position behind and above the cooling water pump.