Problems? Heat and Pressure.

That doesn't speak to the rising temp tho.And the stat only sets the minimum running temperature. I see an IR gun in your future.
Was it overheating with the cap open and the rad full. Or did I get lost too?

But if liquid came out of a seam, the rad needs to come out for repairs,That's all there is to that. Once it is out and upside down mark the spot and start grinding it out, you will soon see the fracture line.