marine westerbeake 30 overheats strangely

Message Title: Message Text:  http  https  ftp  mail    hr     highlight   LI   Quote  Select Emotion SmileWinkSadEmbarrasmentDisgustedBig GrinMadShockedTongueCoolFrownConfused [q]My sailboat has a westerbeake 30 (4 cylendar) engine. The engine overheated (200 deg F) after less than 10 minutes of being tied in its slip in gear at 1700 rpm. In trouble shooting I found that the thermostat had been removed sometime in the past. After several days of trouble shooting I realized that the engine overheats if there is coolant in the fresh water side, but does not if there is water or a borax flush solution in the fresh water side. When it does not overheat, I can run the engine under load at 1800 rpm for over an hour with the temperature staying under 180 deg F. I have: cleaned the raw water side of heat exchanger with muriatic acid solution; used external meat thermometer to verify accuracy of temp gauge; back flushed fresh water side with a garden hose; inspected raw water pump impeller; pressurized the fresh water side and found no leaks; flushed and ran fresh water side with borax solution for an hour each time for five times; removed and inspected fresh water pump. A friend who is a salvor explained it this way. The coolant does not transfer heat as well as water and with the thermostat missing, the coolant is simply passing through the heat exchanger too fast to transfer enough heat. I plan to return to the boat and install a new thermostat in hopes that the problem will be solved. Any comments????? Mike[/q]

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