Friend and I took our KSeries Midgets to Nurburgring for a spin; his 'head-gasket' went whilst we were enjoying a drive in the environs - so his car was shipped home and we carried on in mine. The symptoms were: excess gasssing was causing the coolant to be ejected, when the engine was under-load, and severe over-heating.
I wasn't sure the gasket had gone, after a number of tests, but couldn't put a finger on it!
Back home some weeks later, he took the head off and the gasket was in good condition; he skimmed the head and put it all back together.
It still continued to lose water from the cap... and so he tried another one, and the 'head-gasket' was cured.
It turned out that he'd replaced the expansion tank a couple of weeks before the trip from a top-name supplier... and they'd given him the wrong cap !!! It seemed to fit well, but clearly didn't.
I wonder how many 'head-gasket-fails' are the result of something similar?