there can be several reasons, however it is usually due to overheating and/or sudden cooling --- such as overheating the engine and then pouring cold water into the radiator, etc. Occasionally, the engine manufacturer may have a flaw in the head casting or too thin metal, etc that will cause it to crack too.
A car can be driven with a cracked head, but not very far. Once the head is cracked, the engine will start mixing oil and water and it is likely that the motor will lock up.
No
A cracked/warped head, Blown head gasket, cracked cylinder wall, or cracked/warped intake manifold.
A bad head gasket or a cracked head(s).
A bad head gasket or a cracked head(s).
Blown head gasket - Warped or cracked head - cracked block.
This is often a cracked head gasket between oil passage and a cylinder.
To tell if the head is cracked, you have to remove it from the car, so you will replace the head gasket, anyway. Take the head to a machine shop and have it magnafluxed to see if it's cracked.
Blown head gasket, cracked/warped head, or both.
cracked or warped head/blown head gasket.
Blown head gasket and/or cracked head.
Bad head gasket? Cracked Head? CRacked block?