I guess a blown head gasket could keep it from running but it would have to be severely blown. I would have figured it would have at least run - kinda scratching my head on this one. I'm sitting here wondering if there may be a head "warpage" issue. The story will be told when you get the head off. It is a diyer job as long as you take your time and "mark" wire/vacuum hose connectors and such. Study the books/manuals and take your time pulling those slide rail pins and such. Put the engine at #1 at TDC prior to taking everything apart. It is my experience it just makes it a little easer during reassembly.