2007 Kia Spectra has coolant loss. Pressure test
in this case i would suspect the water pump,it would not really show up in a pressure test ,put a paper liner under the car at night and see if any water shows up on it in the morning,if it is ok, then the water could be lnternal ie the engine is taking the water,but 2007 engine should not have this problem unless it has a very high milage.one more [simple] answer is the coolant leaking from a simple loose conaction and drying up before you see it ,but water leaves a trace so have a good look about the engine for that water mark,please rate this answer.adrian,,,,,,,,,,,