I hope I can help here. After buying my Ericson 323 in 2018 I was experiencing occasional episodes where the raw water would suddenly not not exit boat at the stern, which is difficult to see by the way and my engine temperature would rise quickly. Once I lucked out when my dock neighbor noticed steam exiting where the raw water would normally exit. First I check the raw water strainer which was clean and full of water and then made sure the through haul under the boat was clear of any debris. Next, I opened the bleed nut on the Oberdorfer raw water pump and noticed that water was not streaming out. I then opened up the pump and found that the newer impeller which I replaced right after purchasing the boat had failed as mentioned in the blogs above. I again lubricated and replaced the impeller with an extra I had purchased and was able to get the raw water flowing again. Weeks later and the same problem occurred all over again. I finally discussed with my mechanic and he suggested we replace the raw Oberdorfer water pump and at the same time we replaced the raw water hoses and the through hull fitting. Upon removing the through hull nipple and hose, we found it to be almost entirely blocked and the hose was cracked at the bend. It has now been nearly a year and I have not had any more issues with the raw water system. In fact, it may not have been necessary to replace the raw water pump at all, but now I have an extra pump.
Christian - It is surprising that the 80's Ericson 323's do not have a overheating alarm to help avoid overheating that could easily and quickly destroy a very expensive diesel engine. To make matters worse because of the reverse transom, it is almost impossible to visually check if the raw water is flowing from the cockpit while underway. In fact, my prior 78 Ericson 27 at least had a visible cockpit red light which would come on if I forgot to open the through hull before heading out. Are you aware of any aftermarket solution to add an overheating alarm for the 323? By the way, I have really enjoyed reading your book Alone Together, and learned so much from you experiences. Thank you.
Chris Martz
87 Ericson 323
M25XP