1. Mine was doing that, and I had a bad radiator cap of all things. It would boil over.
2. I noticed this weekend my fan was running all the time, and when I shut it off, I could hear coolant boiling, and it turned out that I had so much crap in the radiator that got past the screen in front of it, that I had to pull the radiator out, and get a pressure washer to clear it all.
I do a lot of "running over stuff" with mine to make trails when I am at the hunting club, which I am sure contributed to all the debris packed into the fins.