Slant 6 Turbo 68Dart Project

d55dave said

If the head gasket was popped and a small amount of combustion gasses were being pushed into the coolant they would go to the highest place (heater core) resulting in no heat. The additional pressure will push coolant past your rad cap. You need to borrow a tool to pressurize the coolant system and see if it holds pressure. When you pulled the plugs was one of them significantly cleaner than the rest?

My 2 cents

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I'll have to find that tool. We don't have one. But someone around my shop might. The plugs were all tan and looked like they'd been working perfectly. No one was cleaner than the rest.

I'll run a comp test and see if anything's changed from where it was before. I have not refilled the system with coolant because I feel like I'll need to get at the head gasket. I would just hate to pull it apart to find nothing wrong is all, and then wind up even more lost.