Well, here goes again. My rig is still using water, but maybe I'm a bit closer to solving the problem. Okay, I'm running a 4.6 liter, used to have a 4.2, and had no problems. I use about a quart of water per day....that's the problem. New development, I just put a water temp gauge in the radiator as suggested some time ago by someone here that described a way of slipping a manual sending unit into the upper radiator hose....Great trick!!!! worked easily, no leaks!!! Anyway, it turns out that my radiator temp at cruising on the highway is up to about 260?. If I am correct, water boils under 16# pressure at about 135?(learned that here too). Is the water evaporating? I am running a 195? thermostat, and the radiator never boils over, and the resoivor tank doesn't boil either, I just lose water. I had my radiator rodded and tanked too.I am not running a shroud, hard to find in Mexico, but I can have one made if necessary. Is my radiator temp normal?? I don't show any signs of water in the exhaust, so I don't think it's a head gasket. I have one other suspicion....It may a freeze plug on the rear of the motor. I had a helluva time getting new ones in when I put the new motor in, and had never done this operation before. I may have made one out-of-round. This would be my worst nightmare, having to pull the motor again to do exploratory surgery. Anybody got any suggestions, comments, theories? Thanks in advance......Rob