I'm having a problem with my kia sportage 2002. My radiator is losing too much water. I topped it in the evening with 5 liters of fluid. In the next evening it was empty after driving about 20 kilometers. First, I checked to see if there is any sign of leakage beneath the car and tested all the hoses. Then, I checked if there is any sign of leakage of water in the engine with oil still nothing discovered. I checked with a mechanic we did a pressure test and he put a coolant to be sure that no hose is defected still no sign of leakage. The problem is persisting it's been like one month my mechanic told me to check it every morning and top the radiator with water. So guys I will be thankful if anyone has a solution or suggestion to my problem? P.S: there is no sign of overheating temperature is normal.
It sounds like a blown head gasket ... I'm surprised your mechanic didn't suggest that to you. If there is no sign of visible leakage, it has to be going somewhere. There are only two other places for it to go. Into the crankcase or out the tail pipe getting burnt. You should be able to smell and see it coming out the tail pipe (you may see signs of excessive white smoke from the tail pipe, but may not be easy to see while you are driving).
There is one other thing which may be happening. If it is going out through the overflow tube during harder operation (something other than idle). You may not be noticing it. You could place the overflow tube in a position where you could see remnants of coolant left after driving. If this turns out to be the case, it could be a bad radiator cap which is not containing the pressure as it should.