Bill, my old 3qm30 had 2 thermostats. My understanding between the raw water cooled and fresh water cooled is the opening temperature of the thermostats. This was from my local Yanmar dealer.
Doug Mountjoy Rebecca Leah LF39 POYC, WA. -------- Original message --------From: William Walker via CnC-List <cnc-list@cnc-list.com> Date: 5/27/18 06:27 (GMT-08:00) To: cnc-list@cnc-list.com Cc: wwadjo...@aol.com Subject: Re: Stus-List thermostat on 3QM30H Josh, I have a drawing from yanmar manual, not quite same as yours. My thermostat cover has bolt pattern different..fore and aft and side to side..I am always confused by "raw water, fresh water" thing...I draw lake water in and through engine and out...no antifreeze or heat exchange..just direct through and out. Bill. Sent from AOL Mobile Mail On Sunday, May 27, 2018 Josh Muckley via CnC-List <cnc-list@cnc-list.com> wrote: Is your engine fresh water or raw water cooled. By the model number I'm guessing that it is raw water cooled. I don't have the manuals for the QM series but believe that they are the predecessor to the HM and GM. As such many of the parts are interchangeable and much of the design is the same. In my parts diagrams it shows 2 thermostats but only on the raw later cooled versions of the HM/GM. I'll send you a picture off list. Josh Muckley S/V Sea Hawk 1989 C&C 37+Solomons, MD On Sun, May 27, 2018, 8:35 AM William Walker via CnC-List <cnc-list@cnc-list.com> wrote: Good morning, Yesterday I removed the thermostat cover on top of the exhaust manifold to replace the thermostat which I suspected was bad. I have a yanmar service manual which has detailed drawings of the exhaust manifold on this sea water cooled engine. To my surprise when I removed the cover there were TWO thermostats installed for and aft on starboard side of the exhaust manifold ports. The Yanmar service manual shows only ONE, in the forward port. Since I only had one new thermostat I installed it in the forward port on manifold, cleaned up the other from corrosion and put it back where it was. The second port is machined to accept a thermostat. If you have a yanmar service manual, pictures of this on page 7-A-2 showing one thermostat. Since these two ports are connected internally and water can flow through both I am thinking that this is a safety factor. If one fails the other still may open and allow cooling water to engine. Any thoughts if this second thermostats belongs there? I have been running this engine with it in place for 7 years and I suspect prior owner did as well for a time. Bill Walker Evening Star CnC 36 Pentwater, Mi Sent from AOL Mobile Mail _______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray _______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
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