I had the exact same symptoms on my 2QM15 for many years. I tried everything I could think of. Finally, when it got worse, I followed the water from outside the hull through all of the parts of the engine. At long last, I found a small bit of an impeller in the hose leading to the area where the zinc is located on the front of the engine (after replacing zincs, and nearly everything else). It was rusty and crusty and must have been there, bouncing around, for years. I know it must have been there before I bought the boat 20+ years ago, because every time I replaced the impeller, it was intact. And, even when it was wailing at me, it had some water coming out of the exhaust, just not as much as it has now.
So, start at the water inlet and look at everything, one careful step at a time. Check the hoses, sometimes they look good on the outside but collapse on the inside, thus blocking water when it is warmed up. Good luck. Gary Nylander 30-1 #593 ----- Original Message ----- From: Dreuge via CnC-List To: cnc-list@cnc-list.com Cc: Dreuge Sent: Monday, October 19, 2015 12:56 PM Subject: Re: Stus-List Engine Overheat Question Al, This sounds like a similar problem I experienced with my old C&C 29 which had a raw water cooled 2QM15. The alarm only came on only after the engine was shutdown for a short period of time and then restarted. I would even let the engine cool at idle speed for a good few minutes before shutting down. I tried many things, and listened to may good suggestions (air lock, pump wear, …), but in the end the problem turned out to be a bad thermostat sender. Maybe that’s your issue too. Do you have a separate sender for the alarm and for the gauge? If so, then it is unlikely that both would be bad. But if not, I would start there. Paul - Paul E. 1981 C&C 38 Landfall S/V Johanna Rose Carrabelle, FL http://svjohannarose.blogspot.com/ On Oct 19, 2015, at 9:03 AM, cnc-list-requ...@cnc-list.com wrote: Date: Sun, 18 Oct 2015 16:08:19 -0700 From: Al Serrato <aserrat...@yahoo.com> To: "cnc-list@cnc-list.com" <cnc-list@cnc-list.com> Subject: Stus-List Engine Overheat Question Message-ID: <411a5ff3-f777-4f52-9bf4-0d90cac65...@yahoo.com> Content-Type: text/plain; charset=us-ascii I'm looking for advice on a situation that arose yesterday. I have a 34 with a 3GMD diesel with raw water cooling. I motored for about 45 minutes at 2000 rpm and then shut the engine down. Everything was running smoothly. The temp gauge showed the normal 100 degrees and I could hear water from the exhaust. I sailed for about half hour but then lost the wind and turned the motor on. The high temp alarm stayed on and the gauge showed 140 degrees. I shut it down and checked the water filter, which looked fine. I tried starting it a couple more times with the same result, so I sailed back to my harbor. When I went to start it, everything worked fine again, and I ran the motor for a good 30 minutes with no issues. The gauge stayed at 100 the whole time and no alarm. I initially thought it might have been the impeller (which is about 1.5 years old right now), but when the problem arose I didn't check for the sound of exhaust water. Since it was working back at the harbor, I don't think the impeller was bad. I'm starting to think that the sending unit malfunctioned and then reset itself somehow but that's never happened before. I'm not sure what temp triggers the high temp alarm and whether the same sending unit goes to both the alarm and the gauge. Am I missing something obvious? Were there other steps I should have taken to diagnose it? I was of course concerned to run the engine for long if it was overheating. What next steps should I take, since everything seems fine right now. Thanks in advance for any help. Al Serrato C & C 34 Fidelity San Francisco Bay ------------------------------------------------------------------------------ _______________________________________________ Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com
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