1999 Ford Explorer • 140,000 miles

Ok I have this 1999 ford explorer and it is leaking antifreeze down under the smog control unit on the front drivers side of the motor. It started leaking in the Spring and it had warmed up enough that I decided to put straight water in until I had it fixed. After I put straight water in it stopped leaking and hasn't all Summer an into the Fall. I live in Maine so antifreeze is a must so I went out and drained it out a couple of days ago and put the proper mix of antifreeze in and low and behold it is leaking again, seems to be only when there is antifreeze in the system. Any ideas or answers would be greatly appreciated.
October 29, 2013.

Pressure check coolant system to see where it's coming form first.

Oct 30, 2013.