Tractor Repair: New Holland tc35d Overheating, discing, loose power

Question
I have a 2001 tc35d that overheats when discing or brushhogging and loses power the warmer it gets. I have cleaned out the radiator fins and tightened the fanbelt but cant get the probelm resolved. Once i quit mowing and disengage the pto or quit discing and lift disc the tractor cools down a bit but still does not have much power. Any ideas or suggestions. Thanks.

Answer
Doesn't sound good at all. If you are getting it so hot that you loose power then it is to late anyway. Using a temperature gun verify that the engine is running hot. If it is then stop the tractor and start with the water pump then the engine. Probably going to be a rebuild if this the case. Either water pump failure, the thermostat is stuck closed.