David – I understand the basic issue is low water discharge which in turn leads to overheating. Some suggestions:
RAW WATER – be sure lines and filter/strainer are all free of debris. Disconnect each hose joint in sequence to ascertain amount of water being pumped. Start at last one where hose from radiator joins exhaust elbow. As a for instance, if water into exhaust is flowing well then the problem is a blockage in muffler or exhaust hose. If not then the problem is upstream. If water flows well into radiator then problem is radiator blockage. Etc. CIRCULATING WATER – replace thermostat if the above does not yield a conclusion. John Read Legacy III 1982 C&C 34 Noank, CT From: David Knecht via CnC-List Sent: Thursday, July 24, 2025 10:18 AM To: CnC CnC discussion list <cnc-list@cnc-list.com> Cc: David Knecht <davidakne...@gmail.com> Subject: Stus-List Re: Water pump mystery Yes- this started with limited water from the exhaust and overheating. I realize I have two separate water circulation paths. I have had the heat exchanger cleaned and pressure tested, checked the muffler and intake path. Last reasonable possibility is the water pump. I know that the existing pump is pumping water when there is no resistance and that worries me. My concern is what happens if I install a new water pump (in progress) and it doesn't fix the problem. I have made too many errors in diagnosing the problem so far to be confident in where the problem lies and I am also worry about multiple simultaneous system failures. So if the thermostat failed or the fresh water pump failed, I would get overheating. That would not explain sense of limited water from the exhaust, but that might not be the real problem and difficult to measure. I am just trying to think about every aspect of the system. Dave David Knecht S/V Aries 1990 C&C 34+ New London, CT On Jul 24, 2025, at 8:31 AM, Rick Brass via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: David; IIRC correctly this string started with an overheating problem? The water coming out of the exhaust is raw water. That side of the cooling system general has only the through hull, the water strainer, the heat exchanger, and the exhaust elbow; all connected by various hoses. I believe you have addressed everything except the heat exchanger. Have you cleaned out the tubes in the heat exchanger? If you sail in salt water they get deposits over time. For my 36hp Westerbeke that is a routine maintenance item every two or three years. For my engine the cleaning tool is a bronze brush intended for the barrel of a .22 rifle that I bought at a sporting goods store. The fresh water side of your engine (which actually cools the engine) has the thermostat, if it has one, the heat exchanger takes the place of the radiator in your car. The fresh water side of the system is just like your car engine. My engine has a coolant recovery tank - which makes monitoring the level of the coolant easy. Not all engines have one. If you have addressed everything in the raw water side of the problem and it still overheats, it may be time to look at the freshwater side of the engine. Rick Brass Imzadi. 38mkll La Belle Aurora 25 mkll Washington, NC Sent from my iPad On Jul 23, 2025, at 7:02 PM, Jonathan Tebbens via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: https://www.westerbeke.com/parts%20manual/200144_m4-30_parts_man.pdf Pg 31-32? Jon Tebbens '78 Mega 30 Katherine On Wed, Jul 23, 2025 at 5:13 PM David Knecht via CnC-List <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > wrote: I am in the process of installing a new water pump to see if it fixes my engine overheat problem. I still think the main problem is not enough water coming out of the exhaust so keying on the water pump. But something occurred to me today while working on it that I had not thought of before. Is there a thermostat somewhere in the engine (Universal M4-30)? Can those malfunction? I presume if it did not open, the engine would overheat? I don't even know where the thermostat is so have never looked at it but I am concerned whether that is something I need to check. Dave David Knecht S/V Aries 1990 C&C 34+ New London, CT <pastedGraphic.tiff> Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated. Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated. Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
