Cooper S turbo blow into water jacket
My 2008 Cooper S seriously overheated, I have replaced all the damaged parts, she runs very well and idles perfectly. However under load (I assume when the turbo comes in) the filler tank cap sprays out steam. I suspect that the cylinder head gasket is damaged or the cylinder head may be cracked.
My question is should this not be evident even when idling?
If I remove the cylinder head, could it be warped from the overheating? How can I confirm this without removing it?
Any advise would be greatly appreciated.