Went out on a ride yesterday to look at some lakes.Just before I got there I could smell antifreeze. I pulled over and you could here my 235' boiling over, so I got out of the truck lifted up the hood to see. I waited about 20 min. before opening the cap and looked in there real gently to see no water in there luckily I always carry some with me, I checked the water and oil before I left the house. Now check this out, there are no leaks anywhere, and the time it was really getting hot there was no indication on my water temp. gauge showing it hot at all and I know the gauge is good. What do think, heat riser?