I have a '53 Jubilee that I recently put a new 160 degree thermostat and newly cleaned radiator. In the summer when I first start the tractor and let it run for about 10 minutes the temperature gauge goes almost all the way up than drops down to normal. It seems to fluctuate from normal to close to high, then drops down a bit and eventually goes back up, than drops back down, and seems to repeat this over and over. This winter when I used it for the first time, the guage went almost all the way up, but the engine head was hot to the touch, but didn't burn me - felt like a car engine would when hot. The lower rad. hose was cold, the upper warm. When I waited longer, after running for 15 mins. it seemed to run in the "cool" section of normal. Is it just that my thermostat is cycling open close etc. Has anyone else had this issue. The belt is tight, the rad is full with coolant, I don't believe there any blockage in the engine block. Any insight is appreciated.