Electrolysis in Small Block Yanmar Engines
- Thread starter Upwind
- Start date
Thanks for posting this. What you have experienced is (IMHO) galvanic corrosion in which two dissimilar metals are in contact with each other in an electrolyte; in this case, seawater. Electrolysis on the other hand is caused by stray currents in seawater related to electrical problems. My reason for saying this is that the tube bundle was largely intact, while the cast iron (a less noble metal) corroded. Building up the HX shell and then machining is possible, but the machinist needs a manufacturing drawing or precise dimensions in order to create a proper seal. Also, building up cast iron with weld is tricky business. I've seen it done, and done a little myself, but only at sea, when there is no alternative.
My 3GM30F has no provision for sacrificial anodes either, but when I purchased the vessel, there were two anodes on the shaft. They both are pretty bad by the end of the season, and I would expect that if I only had one, it would be completely gone. I have also made sure to clean off any surface rust from the shaft and gear flanges so that the electrical connection is as good as it can be. Hope this helps.
My 3GM30F has no provision for sacrificial anodes either, but when I purchased the vessel, there were two anodes on the shaft. They both are pretty bad by the end of the season, and I would expect that if I only had one, it would be completely gone. I have also made sure to clean off any surface rust from the shaft and gear flanges so that the electrical connection is as good as it can be. Hope this helps.
Sailboat Owners' Guide to Corrosion
Here's a link to a thread about corrosion, particularly galvanic corrosion.
-Will
Here's a link to a thread about corrosion, particularly galvanic corrosion.
-Will
