Lost zinc inside engine

[georgeg305]

It has been my experience that zincs that corrode off will coat with salt, become electrically isolated will NOT dissolve but will end up at the filters in the ends of your heat exchanger

[RaymondR]

Originally Posted by georgeg305

It has been my experience that zincs that corrode off will coat with salt, become electrically isolated will NOT dissolve but will end up at the filters in the ends of your heat exchanger

The 3GM30 is raw water cooled and does not have a heat exchanger, the 3GM30Fis the one with heat exchanger.

And, I have not observed salt deposits in a raw water cooled engine, the sea water in there is hot and there is insufficient concentration of salt at the higher temperature to get anywhere near saturation, however there are occasionally carbonate deposits which are fairly easily dissolved with the vinegar flush (It goes in clear and ends up blackish and soupy-ish so I assumed that's what was happening)

[wesley]

Thanks everyone! I will just keep an eye on the engine, making sure the exhaust and temp seem normal.

[GeneM]

I had the same problem and had to open the heat exchanger to remove the chunk.
Now I make sure the zincs are the kind that have a center wire that keeps them from breaking off.

[Filthywrench]

Can anyone tell me the size of the plugs that hold the zincs on the Yanmar 3GM30? I tried a 22 mm wrench but it's too small and I want to make sure the next time I go to my boat, which is currently 8 hours away, I have the right socket. For my raw water cooled engine there appears to be three zincs anodes - two on the right side of the engine (left side as you're facing the water pump), and one on the back.

I've never done this before but I'm interested in the comment from grahamb that the zincs are easy to check. It looks like one of them requires removing the fuel filter housing, which then requires bleeding the system. Maybe you guys consider that easy, but I don't consider it particularly easy and it's messy. Am I missing something?

Thanks for your help,

Mike

[Wotname]

Originally Posted by Filthywrench

Can anyone tell me the size of the plugs that hold the zincs on the Yanmar 3GM30? I tried a 22 mm wrench but it's too small and I want to make sure the next time I go to my boat, which is currently 8 hours away, I have the right socket. ..........

24 mm and some long levers (breaker bar etc). They can be tight and you might need to use some muscle if they haven't been removed for awhile.

[grahamb]

....probably is 24 mm.....have sold my yacht with that engine....another way to double check may be to contact a zinc supplier ...they may have a listing for that engine and confirm the size.......better still buy a zinc locally if you can......then get socket to fit.....

initially I thought too that I would need to remove the fuel pump........the zinc under there is hard to see.......but its a touch job......no removal.

I painted the socket for instant recognition next time....and found the stubby socket handle 150 mm/6 inch......just the right tool....

the rear zinc was the one that was a 'friction' fit....it 'grabbed' as it turned during removal...and fell into the engine.......so I ground its replacements back...so as not to 'grab'.......worked well....no further drop offs.......

[Filthywrench]

Thank you both. Grahamb, I was going to send you a private message, but others may benefit from this. The one that's by the fuel pump I think is accessible. But there's another one further forward behind the fuel filter that I was referring to. That one doesn't seem accessible without removing the filter housing. I know it may have been a long time ago, but if you have memories of that being accessible somehow, let me know.

[grahamb]

No...I definately did not have to remove anything......I remember having the same thought that is looked such a big deal to remove the zinc ......it is a matter of feeling with fingers to locate the head of the zinc......it is difficult to see I know....... also used a short.....150 mm/6 inch extension bar between the socket and handle.....room was tight......Good Luck.......