Tractor Repair: Cooling issue, ford 3000, gas tractor

Question
Why would my Ford 3000 gas tractor be overheating after I changed the thermostat?  It is boiling over in the overflow.

Answer
If it wasn't overheating before you changed the thermostat then you got a bad thermostat or have installed it upside down. If it was over heating before then you might have a bad radiator or cracked head. I have also seen the cooling water jackets plugged with debris or rust from someone other than yourself using river water instead of coolant.