Is there a way to tell...

[firstRWD]

...how bad head gasket failure has damaged an engine? I'm thinking about Possibly buying a car that has a blown head gasket. I know the effects could range from just a blown gasket, cracked head, and recently learned a cracked block. Is there a way to tell how bad the damage is?

[Danny]

Take it to a machine shop.

[jp_slick]

All i can say is expect the worse and hope for the best.
Thats what i do now

[Cronus]

The only real way to tell is inspecting it. And that requires tearing into the engine. I will say that cracking an iron block normally takes a lot of effort. I understand that m20 heads do like to crack however.

[Scotaku]

All i can say is expect the worse and hope for the best.
Thats what i do now

This.

It's a helluva bargaining chip when you're buying a car that needs known work because of a head gasket. At a minimum the mating surfaces need to be decked and the gasket has to be replaced; you have no idea how long the engine was run once it failed. A complete teardown will cost you even more making the shell of the non-running car less valuable (to you as the buyer!)