David&Joan wrote:

Don:

There are no zincs on a Yanmar 3GM engine, at least not on the few I have
owned. The raw water heat exchanger has cupro-nickel tubes and Yanmar
obvously believes that they won't corrode enough to warrant zincs.

David


Funny, my GM series service manual has details of how to change the zinc
on 1,2 and 3GM and the newer 1GM10, 2GM20 and 3GM30 engines. If you
dont belive me google for yanmar "27210-200300". Now I'll agree that
the 3GM30F doesn't use this zinc but you were talking about 3GMs.

This isn't a lot of help to the OP, and I'd suggest having all required
spare gaskets, rubber washers & a spare zinc anode to hand then
inspecting it NOW after one year. If its more than 1/3 gone, inspect at
6 month intervaals in future. If its less than 1/2, replace now. Dont
forget to buy replacements for all spares used.

Keep one used zinc to block the hole in case you ever need to clean
out the block with Marsolve.

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