The so called 'freeze plug' is a sand casting hole plug. It is the access hole that they get the sand out of the water jacket and seldom do they protect the block. I have on a few occasions moved a vehicle that has set out over the winter with no water in the engine and found anywhere from one to all the freeze plugs laying on the ground. I guess it was cold contraction theory working. Put in new plugs and good-to-go. But, if there was water with no anti-freeze, the engine is probablly cracked.
Truck Tinker
