I've often wondered how many "head gasket failures" were really that in the end. Or maybe the air locks/pressure caps/water pump suggestions that have cured overheating questions. Or were they block failures in the end.
Steve

In the last 8 years I have had overheating 4 times twice it was a rad fault once it was a perished hose and once a leaking expansion tank cap the perished hose was the hardest to find as it was the bypass hose that runs from the rad to the expansion tank it had perished behind the retaining clip and only leaked when running at temp the leak was so small it evaporated but let enough air in to pressurise the system every time I thought it was the heads and spent hours doing compression tests just shows you. I put a new engine in 4 years ago and when I took the old one out and stripped it down and there was no evidence of head probs

I think you will find that a head gasket is never the cause of overheating only the result of it.

stat , shame it burst the heater matrix first :doh: