[quote=IvorMog]Sorry gomog but as far as I can see, it is an expansion tank and that cap is a pressure cap not a simple sealing cap. .
Don't be sorry. I enjoy learning and that includes being corrected.
When I refuse to learn, I know the end is nigh. But look up the part # on the cap and google current Ford cyclone forums and the definitions of what it is. That might clarify a bit.
But you might be right in the sense that Ford uses one of the newer type systems. Closed or a blend of expansion and recovery.
Let's not get into that gamut. We are having trouble merely with the traditional expansion versus recovery.

I am interested in systems I can interact with.
gmg
P.S. I did come up with a helpful tweak for the Morgan Roadster AC systems.