Freshwater cooling a mercruiser

ray9842 said:

I have a 2003 Maxum 27' with a Mercruiser I/O. I have used it in New England for 2 years and am going to be transporting it to Southwest Florida in the fall. I've been told the water in Fl is harder on the engine cooling system than NE water. The boat has a flush system installed. What are the pros & cons of having a closed fresh water cooling system installed? Approximately what should I expect to pay for a job like that? Any info will be appreciated.

Thanks
Ray C.

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MarkSee said:

I remember reading on this forum from one of the experts that once a raw water cooled engine that has been running in salt water for a certain period of time, there's already so much crud that's built up it's actually not a good idea to add a fresh water system. I would think being a 2003 and with at least 2 years in salt water you have already exceeded the window. One of those guys will probably be along shortly and validate or not what I'm remembering and give a better mechanical reason for not adding fwc at this point.
Mark

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Scott Danforth said:

the issue with salt water in the gulf, is that over 135 degrees, the salt starts coming out of solution. with water temperatures of 95 degrees by the time it leaves the engine, the salt is precipitating and acting like a honing rouge.

however like most people have stated, you're already running in salt water, adding FWC at this point wont be helping much.

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Tmakaro said:

...Wouldn't it be better than nothing?

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achris said:

No, it will cause more problems than it will solve. The corrosion process with the salt has started, despite your 'salt away' efforts.. If you then put a FWC system on, the corrosion process will now be concentrated, and the rusty flack will stay in the engine and not be flushed away....

Good luck, and you're going to have to clean out the heat exchanger at least twice a year to avoid it getting clogged up....

Chris.....

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Tmakaro said:

what do you mean by the corrosion process will now be concentrated? I would have thought the rust inhibitor in the coolant would dramatically slow the rusting process? I can see I would have to keep the exchanger clean. Should I continue to run it with raw cooling instead. How many years can I continue like this?

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torcano said:

I just bought a boat in which the previous owner installed a fresh water flush system that he states he used religiously after each time he used the boat. He purchased the boat after 4 years of use in salt water without a flush. I just have changed the manifolds and risers. Is the concurrence here that continued use of this freshwater flush would be a waste of time?

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torcano said:

I just bought a boat in which the previous owner installed a fresh water flush system that he states he used religiously after each time he used the boat. He purchased the boat after 4 years of use in salt water without a flush. I just have changed the manifolds and risers. Is the concurrence here that continued use of this freshwater flush would be a waste of time?

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