Larry
The reason for my test message is I have twice been trying to get a message
out, and for some reason it fails. Since the test worked, I'll try again.

IIRC you had some issues with the coolant overflow tank supplied by Yanmar.
I think it had to do with the overflow tube entering the tank through the
top rather than the bottom. Did you find a better alternative ?

I think I'm having a similar problem. Coolant is transferring to the tank,
and little returns.