Originally Posted by Ford_6L_E350
After a one mile trip, your engine is not fully warmed up. Still, a couple of possibilities:
- Coolant cap. As the coolant warms up it expands (creating pressure), if the cap can't hold the pressure, it will vent. Since this is a known problem and a cheap and easy fix, I would just change the cap.
- Thermostat. It is possible for the thermostat to stick closed, then operate normally once it does open. Again, a fairly easy and inexpensive fix.
I have no other good ideas from this distance.
I respectfully disagree with a portion of this. The problem with the cap not holding pressure has to do with the coolant having a lower boiling point when under less pressure (from a leaky cap). This is only an issue at full operating temp, and the temps generated when driving only a mile aren't going to reach normal operating temps. I think it IS a good idea to replace the cap since it's cheap and easy, but I don' think this is your problem.
If your thermostat was broken in the closed position your vehicle would quickly overheat, since coolant would not circulate through the radiator. If it was stuck in the open position it would take a much longer time to reach operating temp, but I don't think it would result in much else.
No matter what, I think you have a leak somewhere that you need to find. I'd cut a hole in a paper towel or something and put it around your coolant reservoir cap. Other than that, it must be a connection or fitting somewhere. Let us know...
Edit to add: I think your deltas are completely normal, at least compared to the ones I see on my 2008 6.0.