We are having the same problem as Rick and are getting quite stuck. Had the head skimmed new HG on new bolts on, the block was checked by two seperate ppl to see if it was out all was deemed ok.
Now taking the car out at normal boosting was ok, under very hard acceleration (flat out through the gears) its blown coolant out so the expansion tank is full but once its done it once it doesnt seem to do it again.
When you look in rad you cant see the coolant level, nor does it come up when you squeeze the hose. BUT at this level the car does not overheat at all keeps its temps fine.
When you top coolant back up it seems to chuck the same amount out again and stay there again.
Went out in car and gave it a blast and pulled up and felt the rad. It seems be hot at one side, so you cant keep your hand on it, but at the other side its just warm, i.e you can keep your hand there. Wondering if the rad is bad flowing?
Its a big rad kinda same size as a glanza one but big style rad caps on it. Obviously could be very old, but dont wanna be wasting money. Just cant see it being the HG again, after everything has been checked so thoroughly.