As some know I have just purshased a 2005 f350 PSD.. Then took it to dealer for service.. Everything was OK according to dealer cleaned and flushed coolant, tranny fluid, fuel filter and oil change(see my other post)..

Well the dealer overfilled it a bit so on my 200+ mile trip.. I stopped at a rest stop and noticed that the bottle had puked very little(funny though the fluid was no where near the cap... so wiped everything down and set off again...Upon my arival at my destination I popped the hood and heard a hissing noise coming from the Degas bottle cap(the collant wasn't overheating and was well below the cap)little experiment parked the truck on a decline and shook the bottle a little and coolant puked out a little.. So my question is should the cap vent when its not overheating.. .. Because Im wondering if with the cap venting and the coolant sloshing around in the bottle could cause the loss of coolant??? Should the cap vent when the engine is off and not overheating???( I also noticed that the everso slight downward pressure on the cap stops the venting)

Oh yeah one more thing this morning cold (overnight) When I opend the cap It released pressure..So I believe the pressure isnt leaking down significantly..

Also want to mention there is no smoke what so ever and strarts immediatly..

Thank you

Thoughts and opinions