As long as I am moving I don't have any worries, says between 165-180. But get me stopped in traffic and opps, there she goes up over 190. I even set the fan up so I can manually run it starting at a lower temp and although this does help, in bad enough traffic it still gets up there. Now, when I was building it I did bump the radiator and it sprung 3 little leaks. I took it in to have it "fixed" (they used an injectable epoxy to block off those tubes) but come spring driving time while I was go-carting it I noticed it still had a small leak. Soooooo...I did what all idiots do and bought some heavy duty stop leak. Stopped the leak but now I'm worried it clogged up things more then it helped things. I still get a faint smell of anti-freeze while driving but no visible leaks or spots on the floor so I attribute this to the overflow tank being used. My thoughts, if I find no one else has heating issues, is it is time to replace the radiator. Nice winter project. Any thoughts on this?