    
Paul Brogger
Member
Username: broggerp
Post Number: 11
Registered: 10-2007
| | Posted on Friday, March 13, 2009 - 04:19 pm: | 
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I've got a 30-year-old raw-water-cooled diesel (Yanmar 2QM15) in Puget Sound. From a cooling system perspective, the engine looks just about as good as I could expect. The zincs seem to have been monitored & replaced, as there appears to be no major corrosion -- the passages in the head looked VERY good when I recently had that worked on.
While re-plumbing the water intake & etc., I put in a Y-valve that also connects to the sink. I was thinking I'd fill the sink with a hose upon returning to the dock, then run in some fresh water (and/or anti-freeze) so the engine wouldn't be bathed in salt water while resting for long periods.
Then, I got to thinking some more. (It's an issue of mine. ;-) Is it better to just let the thing be filled with salt water, or to alternately fill it with fresh, then salt, then fresh, then salt, etc?
For example, I could imagine (in the absence of any real knowledge) a "salinity gradient" establishing itself in the layer of corrosion inside the water passages. Might I actually accelerate corrosion if I were to be dramatically changing the cooling water's salt concentration at frequent intervals?
Frankly, as good as the engine looks at this point, I suspect I should consider leaving well enough alone.
Any more-informed opinions out there? (Thanks!) |
