2006 XLT Coolant leak

[paulblish]

My 2006 XLT has almost 40,000 miles on it. I noticed that the coolant tank was empty about two months ago. I filled it and watched it and sure enough it was going down pretty wuickly - about an inch a day. I took it to the Ford dealer and they ran a pressure test. The did not find a problem and gave it back to me implying I was nuts and there was no problem. I checked it again a month later and it was empty again.
Has anyone ever hear of this problem? What are the proper diagnostics to identify the cause? The dealer is stuck - don't know what to do it the pressure test does not find a problem.

 

[BrooklynBay]

Welcome to this forum! Check the radiator cap. It might not be holding the pressure, therefore the coolant gets lost through the overfill tank. AutoZone could loan you a cooling system pressure tester with a deposit.