Quote Originally Posted by sprayed99 View Post
If you need a visual of the correct style of cap, here you go.
Indeed that cap is the right style, with a spring loaded gasket down in the neck to establish the designed system pressure, i.e. 18psia or 16psia, and a second gasket at the cap to neck interface to ensure coolant pullback through the hose; BUT you don't need a fancy billet cap to be right. A basic STANT stamped steel cap that has the cap to neck gasket works just fine, too. One works and looks like $1MM, and the other just works.....