The first problem with this sled was that the thermmostat broke. Looking at other forums and the complaints about the yamaha thermostats breaking, I simply removed it. I made sure all the parts were there. The next run it ran 60 miles with no problems. Then I took the sled out yesterday and it had the overheat problem again. I checked the pump and the belt and they both were moving. Yet it seemed like the water wasn't circulating. Is it possible there is a vapor lock? Is there a bleed valve somewhere?