Suggestion, go to an auto parts store and buy a small bottle of uv leak detection dye and a black light, pour an appropriate amount of dye in the engine run it for a short while under the conditions that cause smoke and then look for evidence of a leak. The dye fluoresces under the ultraviolet light and as long as it hasn't had time to spread everywhere it will show you where the leak is. It usually looks like yellow paint is leaking out but only with the black light on it, some really need stuff. Make sure that it's not too bright when you do this, a flash light has a hard time competing with the sun.
