ok ive had this problem recently,after sailing u probably have heeled the boat quite a bit & in doing so dumped out all the water in exhaust line from the water lift back....it takes a few minutes to fill up again !! try pullins off the sea water line going into the exhaust if there is water there than just wait a minite or so till water apears at stern[after re connecting line]
You are right! The engine on my Yankee 30 is midships, so the exhaust water has to travel over half the length of the boat, to exit. After the water in the exhaust line has drained by the heeling of the boat, it takes about 2 minutes to get to the Stearn. When you've just rebuilt the water pump and are sensitive to cooling issues, that seems like an eternity! All is well, thanks for the insight!