I have been trying to research an issue with my wheeler. It is a 2001 Sportsman 400. Last summer it started overheating when a friend rode it. I have taken the fan off and tested it (works fine) reinstalled the fan, and jumped the connecting leads to the temp sensor (closed loop) and the fan came on. So I replaced the temp senor at the bottom half of the radiator hoping to correct the issue, but it got hot again, and started overflowing out the top hole of the overflow container. What am I missing? Is there a themostat to replace that would be the issue, or another problem alltogether? Thanks all in advance for your help and comments!