coolant bottle

Ive been experiencing something with my 3.7l that is a bit out of the normal. The right side of the coolant bottle is filling completly and the main reseviour side draining and no pressure in the top rad hose. So i have pulled the coolant tank out and drained it coz i saw coolant dripping and figured i had a leak. I can now see there is a spout on the back side that is open air flows straight through. I thought these tanks were supposed to be pressurised. So my question is this supposed to be like this see picture circled in red.

They are pressurized
so answer is YES

Tommud yes there is a vent hole or yes they are pressurised so there isnt a vent hole

yes. there is suppose to be a vent hole for the overflow side (smaller side) of the tank.
The bigger side is the pressurized side.

Potentially you have a bad reservoir or bad radiator cap.

I posted that they are pressurized above.......................................