有一台东风-12型手扶拖拉机,它的发动机经常出现过热现象。原来是该发动机冷却系统经过改装,机手为防止在运输作业时水箱的水蒸气蒸发,挡住前方视线,因此把敞口水箱改成半封闭式的。即把原来水箱口封闭,外接一根直径20毫米左右,一定长度的胶管 There is a Dongfeng -12 walking tractor, its engine often overheating. It turned out that the engine cooling system has been modified, the hands to prevent water vapor evaporation during transport operations, block the front sight, so the open tank into semi-enclosed. That the original tank mouth closed, an external diameter of about 20 mm, a certain length of the hose