1954 Johnson Water Flush Port

[BUSTER7]

I'm working on a 1954 Johnson 5.5, Model CD-11. It has a port labeled "Water Flush" How is it intended this feature be used? I tend to think it's to create high flow circulation around the water jacket to clear debris, rather than as a water attachment to test the engine. What say ye, sages of ancient kickers? Buster7

 

[F_R]

It is for flushing with fresh water after a run in salt water. Not necessary to have the motor running to do the flushing operation, but it MUST be in an upright position.