i see what you mean but this is what we couldnt understand, the crack in the h/g is so slight it couldnt get the volume of water back through - the car has run fine since the overheating incident - since the old rad had cracked and was replaced with the ally one no water went in the oil no oil in the water and its ran for months with no leaks - then this hapened:(
the cyl was full of water when i took the plug out it flooded out - i cant believe that it had been running like that without hydraulicing the engine - the chances of it parking up on the exhaust stroke every time seem very unlikely and as said the h/g crack was so slight i was expecting damage in the head or block but we cant see any - before we investigated it the car drove spot on other than the vibrations on idle:(