Is there any way to tell whether it is a blown head gasket or a cracked head without removing the head? Symptoms are white exhaust (steam) from a diesel engine and a loss of coolant. Some serious overheating occurred in the not too distant past
No, Not Ordinarily.
The head has to be removed either way.
More than likely it’s the head gasket. If you do a compression test and find low compression on two adjacent cylinders then it is blown between them. They don’t always blow that way though.
The odds of it being a cracked head are slim to zero. Before getting into any potential head gasket repair you really need to run a compression test on all cylinders. You do not want to go through the head gasket procedure only to end up with a shaky engine due to piston rings and/or valve issues.
You will need a special compression tester for the diesel engine. The tester used for gasoline engines will not work.