2017 3.5L - water sloshing sound behind dash on cold start
 

At times when I start up my 20173.5L EB for the first time on a cold morning, I can hear fluid splashing intermittently behind the dash. This happens when cold usually. Goes away after a minute or two of driving.

I had the Ford dealership look at it but they couldn’t replicate it (because I obviously had to drive it there and it was warmed up).

I read about it maybe being coolant lines getting air in them, and needing to “burp” it be raising up the front end (very high) and running the engine with the coolant cap off. I tried to do a variation of this by parking on a steep hill and running it, but no effect.

Anyone heard of this one?