If you are going to install "taps" in the line for uses other then
engine cooling you MUST be sure that these taps are isolated with
valves and not used while the engine is running.

There are valves and I will heed this admonition.



The main strainer should/must be located below the water line so that
with the sea cock open the strainer fills.

The original installation of the strainer was most assuredly ABOVE the
water line. I believe that it is still slightly above but I am not
positive.

Well now, you've got me digging into Calder. While the text does not
specifically say to install the strainer below the water line the
diagrams, although fairly diagrammatic, surely tend to indicate that is
the way to do it.

I do (at least at times) get water flow through the system with the
engine off. This MUST be due to a siphon effect. I can't swear that it
happens when I am having the overheating problem.

Well I now have one MORE thing to put on my summer to do list.

Make sure strainer is below water level.

Thanks,

Great reply