Have a Yanmar FX-17 that is used mostly for mowing due to its small size. It overheats after using for a short time(~15minutes). Tried cleaning the radiator and using radiator flush which does not seem to influence the problem. Is there some internal mechanism that close circulation down initially for warming that does not open up to allow circulation after engine warms to operating temperature? If you have any suggestion, please also send cc to klby@comcast.net since I do not regularly review this site. Occasional user have problems also. Thanks