ENGINE

PROBLEM TO BE SOLVED: To solve a problem that impurity, crystal or the like of which specific gravity is heavier than cooling water stay at a bottom part of a water jacket, causes clogging, prevents circulation, and leads to overheat if impurity is mixed in cooling water since former water cooled engine has structures naturally circulating cooling water in a water jacket. SOLUTION: This engine 1 having a cooling water tank 6 arranged above a cylinder block 4 or a cylinder head 3, and making the water jacket 12 formed inside of the cylinder block 4 or the cylinder head 3 communicate to the cooling water tank 6, is provided with piping establishing communication between a cooling water outlet hole 21 provided at a lower part of the water jacket 12 and a suction side of a cooling water pump 14, and piping establishing communication between a cooling water inlet hole 18 provided at the lower part of the water jacket 12 and a delivery side of the cooling water pump 14, a joint 28 is installed in a middle of each piping, and the joint 28 is arranged above the cooling water tank 6. COPYRIGHT: (C)2009,JPO&INPIT