setes of Model H85 excavators bought by Dayukou Mining and Processing Plant can not operate normally with the engine overheating during operation.Through the analysis of the system,the original aluminium sheet and fin type radiator for the radiator system has been changed into the copper fin and tube type radiator.Meanwhile,the fan has been replaced,and the rotation speed and blade angle of fan are increased.The site test and measurement has shown that the phenomenon of engine overheating has been eliminated successfully,and a better result has been received after completing the innovation.