What is a blown head?

Answer 1

First-A head gasket is located in between the piston cylinder head and the engine block, inside a car engine.

Now a blown head is a blown head gasket. It causes the engine to overheating. All the engine parts are made of metal. So, when the temperature of an engine heats beyond a point, it leads to the blowing of the head gasket.

The gasket has failed to seal the space between the head and block. This allows coolant to enter the combustion chamber or the oil galleys. It can also mean the head has cracked.