Howdy,

Sorry about the late reply. I don't check PM's - feel free to email akio.kanemoto - at - gmail.com

As for zincs, I have the service manual here and just looking through it, can confirm that there is no mention of zincs in the exchanger. There should be 3 in the engine block itself, but that's it.

Douitashimashite.

Hey Aiko san.. Does your Yanmar have a place for a zinc in the heat eachanger? Friend of mine has the same as yours....and cant find a zinc.. Gordy may says he dont think they do...but thought I would ask.
Domo.