That is common with that type of cooling system. What happens is they over heat and the rings loose there tension. If it is not allowed to run out or oil to where you get bearing damage you can drop the pan, remove the head, remove the rod bearing caps one at a time, push the piston up above the rings, put on new rings, put the piston back down in the cylinder and replace the rod cap.
I find this the easiest way to install the rings on a rebuild as well.(On this engine)