2004 Ford Explorer Leaking Engine Coolant

let me get this right, your engine is leaking coolant no external sighn?

Yes, that is correct. Leaking coolant but no signs of leakage. I had it looked by an mechanic, and he could not fine problem.

if your coolant is going down, that usually indicates that you are burning it up in the combustion chamber, which means you have a small crack in the head gasket, usually when they are this small you can use a sealer that you can put into the radiator to fix the problem.

That's ggryreat. Thank you. I will give it a try. Do you have a sealer you could recommend or one that you find work best?

the way the system is designed, I can not poor the the sealer into the radiator, do I poor it into the overflow/reserve container? I would think that if I poored it into the overflow/reserve, it would clog the overflow/reserve at the stainer. Please advise

get a liquid, the thinnest brand you can find, the overflow should always have a coolant level if do not put it in if there is none in the overflow, wait till you fill to the proper level and read the instructions on the bottle