COOLING SYSTEM OF ENGINE FOR OUTBOARD MOTOR

摘要

PROBLEM TO BE SOLVED: To prevent a cylinder-injection-of-fuel type engine mounted in an outboard motor from supercooling at the time of starting or low-speed operation and to prevent a piston from overheating at the time of high-speed operation. SOLUTION: This system mounts a first thermostat 49 between the water jacket 44 of an engine 6 and a cooling water-exhausting passage 47. A bypass passage 50 communicating its downstream side with the cooling water-exhausting passage 47 is connected to the first thermostat 49 at its upperstream side. A second thermostat 51 having cooling temperature in operation lower than that of the first thermostat 49 is mounted in the bypass passage 50. A closing valve 52 opened when the engine operating region is in the high-speed region is mounted the upstream of the second thermostat 51 at its upperstream side.