"Joe" wrote
The inverted U is called a rise. It is put there to keep water from
coming back on top of your pistons. Now unless you have the system
sealed you will not have enough pressure to overcome the standing
water in the rise. Seal it up, start it up, go outside and look. If
you can see it, not sure how your exhaust is ran it may be under
water. If your winterizing your raw water system that is the wrong way
to do it. What you wanna do is close your seasuction, open your
strainer start the engine as you pour antifreeze into the strainer,
That is if your strainer is properly mounted. This will fill the raw
loop to the riser.

Thank's again. I've been too sick to use the boat for several months and it
looks like the riser where the water from the engine goes into the exhaust
has become completely plugged to let any water through. I can run the motor
briefly and exhaust gas comes out normally but without water. And since it
is plugged no water gets pumped out of the strainer. I disconnected the
hose going into the riser and pumped antifreeze thru the motor to winterize
it (the extra went into the bilge) but will have to fix it when I get my
health back. Thanks again for the info.