a little trick i use for had to find leaks is buy the little bottle of uv dye from any auto parts store and dump it in the rad....if you don't have a black light maybe u could pick up a cheap black light bulb and throw it in any light u have, i use an led black light just for this.....but drive it and then check with light everywere a cooling line runs....even check inside the tail pipe, it will light up if its headgasket....sometimes I have found coolant leaks that only appeared when engine was hot and thermostat was open, and then the leak was spraying onto hot engine components and evaporating but not giving off any noticeable smoke or steam....u can get these uv dies for just about anything.....i invested 30 bucks into my flashlight years after just using a black light bulb from a prank/joke/dollar store...barely gets used but well worth the investment when i do use it....good luck, and let us know what u find