Re: Uh-oh... is this headgasket?
Chech the side of your engine block for water stain. If head gasket is ruptured you will see a white stain coming from somewhere along the head gasket underneath the exhaust manifold. Usually this side. But could be the other side. Or look for water and inhibitor stain somewhere else.
maybe suggest to pressurise your raditor. Get a pressure tested and try to force the water out of the hole (wherever it is). I have used an old radiator cap and pulled the guts out of it and fitted a car tyre tubeless valve and pumped up with a tyre pump. Make sure you attach a pressure gauge and stop at about 15 psi. This should be safe enough and force water out to find where it is escaping from. Sounds like external if no indication of water mixing with oil or vice versa. let us know how you go.