Running rough after 30 minutes

[cornhusker]

I have a Kubota F3680 that is running rough and giving me fits. I can start to mow in low gear and within about 30 minutes or so I lose power and have blue smoke coming from the exhaust. If I go and park it and let it cool it seems to run great again until it gets hot. All filters have been changed, the engine is clean, radiator is full and blown clean and the temp gauge never shows the mower to be hot yet when the majic time of about 30 minutes pass, here we go again. Any sugestions

 

[likearock]

Did you ever find the solution to your problem? Im having similar problems with my B1750