>> My understanding was that if the water flows from the hose at a greater rate >> than it can be pushed by the exhaust gas from the muffler to the thru hull >> then water will accumulate between the muffler and the mixing elbow. >> Eventually it will overflow on the wrong side of the mixing elbow into the >> cylinder... leading to catastrophic consequences. <<
>> Now this is all theoretical knowledge I got from books and forums. << The concern is valid. I was delivery skipper moving a boat from Hawaii to Seattle. The boat had been mostly located in Tonga with trips to New Zealand. The maintenance had been poor for some time. Several days out of Honolulu sea water backed up the exhaust hose (mounting clamps had failed allowing the hose to fall below the water line) flooding the water lift, elbow, exhaust manifold, then the cylinders. As the sea water blocked the exhaust the engine sputtered and died. As we attempted to re-start (we thought it was water in the fuel as this was common) the sound of failure was a solid thunk. (Water locked cylinders) In short, we dried the engine, jury rigged broken valve springs with bungee cord donuts (provided enough pressure to mostly close the valve) and was able to re-start the engine enough to charge batteries, pull down the freezer, and motor slowly. Moral of the story: Prevent cooling or exhaust water from backing up into the engine. Shut the raw water inlet if the engine will be cranked over without starting. Inspect the exhaust hose routing and fasteners prior to leaving Hawaii. Martin Calypso 1970 C&C 43 Seattle ________________________________ From: CnC-List [mailto:[email protected]] On Behalf Of Sébastien Lemieux Sent: Thursday, November 15, 2012 5:35 AM To: [email protected] Subject: Re: Stus-List Winterizing Advice sought for C&C34 My understanding was that if the water flows from the hose at a greater rate than it can be pushed by the exhaust gas from the muffler to the thruhull then water will accumulate between the muffler and the mixing elbow. Eventually it will overflow on the wrong side of the mixing elbow into the cylinder... leading to catastrophic consequences. If my understanding is correct, the situation would be the same for a fresh or raw water cooled engine. I think it is just much easier to rely on the raw water pump to determine the water flow using the bucket trick. I need the bucket setup in any case for feeding antifreeze, so I simply put the hose in the bucket for running the engine. Now this is all theoretical knowledge I got from books and forums. When I changed my impeller this fall, I noticed that the little chambers formed by the vanes never overlap both the input and output openings at the same time. This implies that the fresh water pump will limit the flow of water pushed into the engine, no matter the flow of water that the hose is set to deliver... Unless the hose pressure is high enough to bypass the vanes. Or if the y-valve is installed after the raw water pump (which would be a very bad idea since the pump would run dry). Sébastien Lemieux Merlot X - C&C 30 mk2 1987 Mooney Bay - Lake Champlain
_______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com [email protected]
