wow, such language ,, where do i get the path to that apparant easy knowledge of yours,, i dont get that yours has more exlanation but i still cant help my childrens,,lol

like the previous answer, if those more obvious things dont pan out, you may have to flush the engine replace the thermostate, especially if you had to replace the water pump in the recent past!,, and if you never put coolant in the first place corrosion has to be eliminated, or say kept up on it,, or the dang water pump has already quit and you haven't  replaced that,,good luck