What I had wrong in the original article was the direction of the water flow. Additionally, where the raw water enters the exhaust pipe was in error.
Here's the updated picture:
This morning I had an interesting conversation with the mechanic and the fellow who has this motor in his tractor.
I'd directed him to the webpage with your comments. You are far better at articulating what was perceived wrong than I would be so I let your advice speak for me. Thank you. Thank you a million times.
This is what I learned:
#1) The diagram water flow was wrong. The water will push into the tank and then flow from there back to the heat exchanger. That's why the tank will always be full. Air will not be an issue.
The heat exchanger will be mounted above the manifold/riser.
A separate water pump will push the water in.
What needs to be determined however is rate of flow. Too much and the engine will be too cool. Too little and the reverse is true. The mechanics have been discussing a valve set-up for regulating the speed fluid flows through the box.
Also, they state that once set, I should be good-to-go. No further adjustments required.
Additionally, rather than have the raw water spray in just after the top elbow, it will be just prior to that exit pipe on the far right. I have been assured that this is okay.
They seem quite adamant that this is functional and workable. I did not (yet!) ask why an elbow such as Eric has was not used. That will come tomorrow. For today, life is again sweet.
The rain is falling and that means the shrimp boat is not running their compressor and grinding at rust. They are doing a major overhaul, tearing out an ice maker and installing a freezer. The ice maker worked fine all winter, but not in the summertime.
Anyway, with many many thanks. I'll will continue to keep you updated, though nothing will happen to my boat until next week. They are busy tomorrow and Saturday, and even expanded their workforce to add another employee. That's a good thing.
And with your help they know eyes are on them. That cannot do anything but help. Thank you for being in my corner. I appreciate that more than you can imagine.