I have a 718D grasshopper. It has been overheating on me. It started overheating last season and I ended up replacing the radiator but was mowing with it again this season and is still over heating. It is okay at idle but when you are mowing with it the mower will overheat. Then if you turn the the deck off it will cool down and you can go back to mowing until it overheats again. Any information on what could be causing the problem would be greatly appreciated.