I just bought a 97 GMC Sierra with a 5.7l I bought it with the intention of replacing the motor. It was believed to be a blown head gasket problem. I filled the radiator and ran it for about five minutes yesterday and after I turned it off there was plenty of coolant in the oil and the radiator had lost a significant amount of coolant without a visible leak. Leads me to believe it is a blown head gasket, but I tried to start the engine today and the starter just “clunks” once. I’m thinking the engine is hydrolocked. My question is, would it be worth it to pull the engine apart, replace head gasket and hope the block isn’t cracked? Or should I just scrap the engine and call it. That or is there a way to tell from home if the block is cracked?