Just posted on other thread YES a real PITA to get to and replace on my 3HM as well $678 bucks later its done ! ouch!! ☹
John Conklin ________________________________ From: CnC-List <cnc-list-boun...@cnc-list.com> on behalf of Nauset Beach via CnC-List <cnc-list@cnc-list.com> Sent: Monday, May 28, 2018 10:53:45 AM To: cnc-list@cnc-list.com Cc: Nauset Beach Subject: Re: Stus-List thermostat on 3QM30H > Exhaust Elbow Cleaning Rick &/or anyone else, Is there a recommended “service interval” for checking / cleaning the exhaust elbow on a fresh water cooled 3GM30F? Mine was last checked 3-4 years ago and have probably had 100+ hours operation during that period. It is a real PITA to access / remove / reinstall that elbow. Thanks, Brian From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Rick Brass via CnC-List Sent: Monday, May 28, 2018 10:16 AM To: cnc-list@cnc-list.com Cc: Rick Brass <rickbr...@earthlink.net> Subject: Re: Stus-List thermostat on 3QM30H Bill; A “raw” water cooled engine passes water from outside the boat ( in your case lake water) through the engine for cooling. A “fresh” water cooled engine has antifreeze in the engine and a heat exchanger, and the lake water only passes through the heat exchanger to cool the antifreeze circulating inside the engine. Josh’s note about making sure you have the correct thermostats installed in your engine is spot on. A raw water engine uses a low temperature thermostat and has a low operating temperature. I would have guesses 120-125, but Josh found a spec of 108 for the thermostat. Your operating temperature when the engine is under load should be around 140-145. That helps to prevent deposits inside the engine that will block the cooling passages. A fresh water engine runs at a higher temperature – diesels are more efficient at higher temperatures. You use a 165 degree thermostat and the engine can get to 180-190 under load. One consequence of the lower temperature in a raw water engine is that there is increased production of unburned hydrocarbons and soot. Back in the day, when I was a Yanmar certified technician and teaching diesel mechanics, the consensus among the mechanics was that the exhaust elbow on the Yanmar 2 and 3 cylinder marine engines should have the carbon buildup cleaned out every 50 to 100 hours – at least yearly – as preventative maintenance. On a raw water engine like yours, that would be a very good idea. Rick Brass Washington, NC
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