Leaderboard

Ooo. Not fun, and yes, it sounds like there's air trapped there in the throttle body and upper hose connection. I'd start with a pair of locking pliers ("Vise-Grip") on the outside of the filler bolt head and see if you can get it off that way. Once there, fill the cooling system from that opening and that should take care of your air bubble/overheat issues. From what I could look up on Lexus parts sites (the diagrams aren't the easiest to read), so it looks like that filler bolt part number should be 90341-20012, and the washer/gasket below that should be 90430-20017. Hope this helps. Best, Paul