I'm having an issue with my Navigator I'm hoping you guys can help me with. I just bought it like a month ago so I don't know a ton about it. It had a small leak by the upper hose, which I thought was a clamp so I replaced it. It still leaked so I was thinking it was a small hole in the radiator or the plastic side of the radiator. Not wanting to drop money in this thing, I threw a bottle of K-Seal stop leak in there. It stopped leaking. Four days later, I'm driving and my temp gauge pegged. My scanner showed it was at 240° so I got off the interstate and shut it off. Eventually opened the tank and it started boiling and sucked it dry into the block. Bought 2-gallons, first gallon immediately sucked into the block from the tank, second one did the same after squeezing the hoses with coolant in the tank. Bought a new cap, made sure it was full and pumped the hose. Kept an eye on it all week, via my scanner and it was perfect. Still no leaks either. Today, I happened to check my scanner while driving and it's at 220°. Got to 225° and while I was backing into a parking spot, it hit 235° and dummy gauge started climbing. Shut it down, let it cool a few hours and checked. Tank is still full, upper and lower hoses were equal temps (to the touch at least) squeezing the hoses blows into the tank so it's not clogged that I can tell. I have no clue what to do next or what it could be. Any suggestions?