Possible Headgasket , coolant bleeding . please help!

[Comedywizard]

I recently replaced the metal coolant pipe that the end had rusted off and put everything back together to get the van running. Having trouble bleeding the coolant but suspect possible headgasket? Please help.

I've left out the thermostat to flush through the system and to help with air lock but as soon as I start her up, coolant comes out of the rad or expansion tank like a volcanic geezer and the top hose feels like it bubbling inside, like a kettle. This is just after start up so van not yet hot.

Am i right to think headgasket has gone and the bubbling is caused by engine compression getting into the coolant system?!

If it is headgasket will have to think if its worth doing or cut my loss and break the van.

Any other members local that could help me?

Would be grateful for any advise. Thanks