Onan Electrolysis


ianjenkins1946 <ianjudyjenkins@hotmail.com>
 

Our SM is no 302, June 2000 launch, now with 1950 hours on the Onan.Some time ago I mentioned on this forum that I had suffered from electrolysis on the heat exchanger. This became evident almost from new. Onan UK couldnt understand it, would not confirm that it was electrolysis and told me that in their experience the anode was unnecessary. However, when I showed the problem to La R on a visit there after two years they recognised the problem and added an earth strip from the heat exchanger to the tray.
Unfortunately this did not stop a leak developing in the heat exchanger about a year later. I assumed that the damage must have preceded the addition of the earth strip. I could not get the hole welded as apparently the heat exchanger is mad of some alloy which does not lend itself to repairs of that sort, and so I bought a replacement ( some $300 odd).
However, although earthed from the start, the new exchanger is going the same way ( After about 700 hours). The paint is bubbling up where the seawater intake pipe joins the body of the exchanger, with the metal pitting with a product that looks like salt ( but isnt) and now, ironically, the paint and metal around the anode entry point is following suit.The anode itself is almost untouched.
It seems to me that it is matter of time before this exchanger goes the way of its predecessor, which I have kept and patched with epoxy as an emergency spare.

Has anyone else had this problem...and found a solution?

Having said all this , we have just completed a wonderful season , some 4,500 miles over six months sailing two handed between Puerto Montt in Chile to Piriapolis in Uruguay, via the Chilean canals and Cape Horn ( where we landed and visited the lighthouse keeper and his wife), anchoring in over 50 remote anchorages and finishing with a blast of a sail from the Le Maire straits to Mar del Plata, averaging 174 miles a day for 8 days, with wind speeds topping at 59.7 knots, and the only thing that went wrong the whole season was the light bulb in the fridge which packed up on our last day. About par for the course for an Amel, I guess.
Cheers, Ian and Judy Jenkins, Pen Azen, Piriapolis, Uruguay.

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