From the sounds of it you have a leaky head gasket or crack in the block between the cylinders, I had both. Mine didn't overheat but would burp allot of air once I turned it off. Also, remove the coolant drain plug to the left of the disturber and pull out your temp senor. The replacement motor I bought had about 2 cups of loose rust built up around the rear cylinder and you can see the loose rust thought those holes. I used magents and lots of patince to get it all out plus a good flushing of the block. You may have a similar problem or a coolant jacket blocked.