my Yanmar anode doesn't need renewing but..................!

[Modulation]

after 18 months (12 in seawater and 6 in brackish water it definitely should. I removed it yesterday to replace it and found 75% of it still intact - a tad worrying. The boat is marina based and permanently connected to shore power.
Where do I start to find out what the problem is and what's likely to have been eroding instead/?

Thanks

 

[NormanS]

after 18 months (12 in seawater and 6 in brackish water it definitely should. I removed it yesterday to replace it and found 75% of it still intact - a tad worrying. The boat is marina based and permanently connected to shore power.
Where do I start to find out what the problem is and what's likely to have been eroding instead/?

Thanks

My Volvo doesn't have one

 

[VicS]

after 18 months (12 in seawater and 6 in brackish water it definitely should. I removed it yesterday to replace it and found 75% of it still intact - a tad worrying. The boat is marina based and permanently connected to shore power.
Where do I start to find out what the problem is and what's likely to have been eroding instead/?

Thanks

You dont say what engine or if its raw water cooled or fresh water cooled with an anode in the seawater side of the heat excahnger.

Presumably the anode is fitted into some sort of holder which is screwed into the head or block in the case of a seawater cooled engine, or into the heat exchanger in the case of a fresh water cooled engine.

Make sure there is good electrical contact between anode and holder and between holder and block/head or heat exchanger .

Some VP engines have heat exchangers which by virtue of their design do not need anodes. Some of the older raw water cooled VP engines just did not have anodes!

 

[vyv_cox]

The zinc can become passivated, i.e. Have a white layer on its surface, which should be removed. Ideally not with anything made from steel but probably not all that important in reality.

 

[blackbeard]

Assuming it's a 1GM, raw water cooled.
I inspect mine annually (and clean it up), but usually it's OK for further service after one year.
After 2 years there's still a fair amount of zinc left, but I chicken out and replace it.
I have always assumed I don't have a problem ...

 

[Cloven]

after 18 months (12 in seawater and 6 in brackish water it definitely should. I removed it yesterday to replace it and found 75% of it still intact - a tad worrying. The boat is marina based and permanently connected to shore power.
Where do I start to find out what the problem is and what's likely to have been eroding instead/?

Thanks

To follow up on the possibility of Zinc pacification, you say you were 12 months in seawater and 6 in brackish water. Was this 12 consecutive months seawater followed by 6 months brackish? If for example you had 6 months seawater/6brackish & then 6 seawater, there is every chance the Zn became passive during the period in brackish water and therefore would not work for the latter period in seawater.

 

[coreng]

Why should it be a problem? Anodes depletion occurs only if there is a demand for protective current. Only a potential measurement of protected metals will tell you if your system is safe and everything OK with it. Otherwise, it's just a guess. And this is a strong recommendation issued by main drives manufacturers (incl. Yanmar and Volvo Penta), major classification bodies, your own NPL and ABYC...

 

[Old Troll]

Yanmar anode

Assuming it's a 1GM, raw water cooled.
I inspect mine annually (and clean it up), but usually it's OK for further service after one year.
After 2 years there's still a fair amount of zinc left, but I chicken out and replace it.
I have always assumed I don't have a problem ...

I too have a 1GM10 and have similiar wear on the anode and as you say replace after two years. There is no evidence of any problem over the last ten years.

 

[Modulation]

Thanks for replies.
Engine is 2gm raw water cooled and is 6 months in sea water followed by 6 months in brackish every year.. The reason I'm concerned is that the depletion in the anode used to be higher than this . An anode would customarily last 12 months before neeeding to be replaced. .

 

[Cloven]

Thanks for replies.
Engine is 2gm raw water cooled and is 6 months in sea water followed by 6 months in brackish every year.. The reason I'm concerned is that the depletion in the anode used to be higher than this . An anode would customarily last 12 months before neeeding to be replaced. .

Referring to post #6 above, I am almost certain that the raw water cooled Yanmar 2GM has two internal anodes. Have you checked both? Apart from the passifisation issue, it could be that one has become depleted essentially saving the other.

 

[Modulation]

Thanks. I checked the manual when last on the boat and it indicated only one anode. That said I had a different boat earlier aalso with a raw water cooled 2gm20 and that DID have 2 anodes. When I next go down to the boat I'll check for a 2nd one. You could well have hit on my problem!

 

[Cloven]

Thanks. I checked the manual when last on the boat and it indicated only one anode. That said I had a different boat earlier aalso with a raw water cooled 2gm20 and that DID have 2 anodes. When I next go down to the boat I'll check for a 2nd one. You could well have hit on my problem!

Just checked the Yanmar workshop manual, shows 2 anodes for the 2GM, one one the cylinder block and one on the cylinder head. Page 53, diagram 23.View attachment 38165

 

[Cloven]

Just checked the Yanmar workshop manual, shows 2 anodes for the 2GM, one one the cylinder block and one on the cylinder head. Page 53, diagram 23.View attachment 38165

Couple more pics might help:

View attachment 38168View attachment 38169

 

[Spi D]

Many anodes seem better than they actually are. What counts is the mass (weight) left after the season.