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Hi new to the forum and have a question reguarding amy 03 civic ex cooling system.Ok First off at slow speeds or idle my car blows little hot air when on the the highway it blows hot air.Second with no reason temp gauge will go hot then return to normal stay like that for 10 minutes then creep again.Ive chg'd the thermostat and coolant temp sensor and it still does it.Chk'd oil and it appears good as well car does not blow white smoke what could it be radiator cap?water pump? etc any help would be great..........