If you have seen the older Detroit series of engines as mentioned you will find they are 2 stroke water cooled. Used in lots of applications including boats and other equipment. Locomotives may still have them also.
With this series the clyinders are wet sleeve. They are sealed on the top and also near the bottom with most having 3 o ring's which is a press fit for sealing. The water circulates around the sleeve for cooling. The engine is also different and more complicated than normal 2 strokes as it has valves for intake and piston porting for exhaust.
In there day they where very popular but they also had there problems. I have never seen one that did not leak somewhere and if used as a unattended power plant and if they broke the quill shaft you would understand why they called them screaming jimmies. Almost instant destruction with the block looking like a seive from the rods sticking out.
Retired mechanic,
John