bubbles in expansion tank?

[fax0815]

Hi,
just a quick question which I cant figure out at the moment. I´m having airbubbles in the expansion tank, constant once its warm and it does overflow a little one you race it.
The waterhoses don´t feel like they are at 0,9bar. So I thought rad cap I´ve changed the rad cap for another one in unknown condition and it does the same.
Rad cap seat in radiator hasn´t got any visible damage.
Might buy an uprated rad cap like on all my other cars?

I don´t suspect headgasket since the engine is 3000km old, and the head was skimmed and OEM gasket was used.

It still does have all the original Toyota waterhose clamps everywhere.

Am I missing something?