Sorry for the absence, I have been out of town. But before I left I used some heavy card stock in front of the of the radiator to block air flow but never got a chance to run it. Having finally gotten back into town and a day off of work I was able to get the tractor out and see what would happen. And what happened was I was finally able to get the engine up to full operating temp (4 bars), also the smoking and smell from the exhaust went away. I think this adds to the certainty of the thermostat being faulty.