My guess is the pump is where your leak is coming from ! It will only leak with a hot motor, or while running. With the temps in your area.
To test the pump. Grab the fan shaft & wiggle it (while motor is warm). If there is any movement, your pump is shot. Another trick to proving the leak is coming from the weep hole on the pump. After you park it for the night (day?). Place a dry rag under pump to catch coolant ( REMEMBER to remove rag before restarting motor! ), Leave sit for several hours so that motor cools to the point of being cold. If the rag is wet, the pump is leaking. Before making this last test, make sure the motor got to running temp, & it has a full load of coolant !
Ford Man in Michigan
Friday, January 14th, 2011 AT 6:17 PM