dvdbrgdn

Okay so i just bought my 4.9L and went to check the coolant levels. Popped the rad cap (cold engine) and cannot see any coolant in the radiator. So opened the bottom rad plug and nice green coolant started flowing out (but not too fast it was kind of a trickle). So I'm thinking there must be atleast some coolant in it. Next I look at the overflow tank and to my surprise, it's over half full of straight water. Something doesn't seem right to me. Should I drain the water from the overflow and fill the rad with coolant? Also, the truck does not overheat ever, even in hot weather. There is smoke white smoke coming from the tail pipe but it is very faint unless I really romp on it. There is quite a bit of water coming from the tailpipe but it doesn't SEEM to smell or look like coolant. Please any advice will help