Zinc pencil on Yanmar 3GM30F

[jgsteven]

Hello,

I have a Yanmar 3GM30F in my boat, and the manual says I should replace the zinc pencil at last yearly. The manual states that the pencil is labeled with the words 'anti corrosion zinc', but I have looked all over the darn heat exchanger and can't find the thing (maybe the label sticker fell off?) -- the manual doesn't have a diagram pointing to it either.

Can anyone who owns a 3GM30F explain where the zinc pencil is, or send a picture showing me where to look! I can't bear the thought of my poor engine corroding, but I don't want to start randomly removing bolts looking for the thing...

Regards,

--
Joe

[camaraderie]

Pehaps this will help...looks like there are 2 zincs.
Yanmar 3GM30(F) | 15. Anti-Corrosive Zinc

[nk235]

I have a Yanmar 3GMD with the same exact zonc setup. I am due to replace mine very soon...just waiting till spring commisioning time so I don't have to re-winterize the motor after flushing the cooling system to change the zincs.

Let me know how it goes when you change them and if there is anything I should know. One thing I noticed is the bolt for the zinc on the left side of the motor is almost impossible to get to as there is a fuel line or something right in front of it. Should be fun...

[Vasco]

They no longer put zincs in the 3GM30F but at the rear of the motor, above the transmission, you will see a plate where the zinc used to go. I have had mine since the early nineties and no problems. I too wondered about it as the manual does indicate zincs but Yanmar claims they're so good they don't need them. At least this is what the dealer told me.

[badsanta]

I will have to check. But I was told by several sources that there are NO zincs on the F model. Any other yanmar owners, what do you have?

[eherlihy]

Originally Posted by camaraderie

Pehaps this will help...looks like there are 2 zincs.
Yanmar 3GM30(F) | 15. Anti-Corrosive Zinc

Lookin' at the diagram I see;
Ref | Part number | Description................. | Qty for 3GM30
3 | 27210-200300 | ZINC, ANTI-CORROSIVE | 2
6 | 27210-200300 | ZINC, ANTI-CORROSIVE | 1

2+1 = 3 by my count

[bubb2]

I know about the 2gm20F, I went though the same thing and found out the fresh water models do not have zinc's, the raw water ones do. I spent hours going over my engine and manual. I called Mack Boring, they gave me the answer and said they get this question everyday.

[menado]

My Yanmar 2QM15 has 2 zincs one near the transmission and one in front. But my engine is raw water cooler. For fresh water cooler engine the zincs should be in the heat exchange at the raw water chamber. Unless the heat exchange is made of bronze that no need zinc.

[FarCry]

I took the 2 plugs out that are supposed to have zincs on my raw water cooled 2QM15 yesterday. Only thing left is the threaded piece that screws into the cap that the zinc is supposed to be attaced to. Perhaps I should have not given up so easy last time I tried to get to the front zinc. This time a 2' cheater pipe on the end of wrench was just enough leverage to get it out. I hope your goes better!!!!!!!

[HerbDB]

This has been debated many times over the years. My last two boats have had Yanmar 3GM30F engines. I attended the Mack Boring diesel engine course. This engine does not have a zinc in the cooling system. Here is some of the text from my engine course.

"Yanmar uses cupronickel heat exchangers. Extremely low to non existant corrosion factor so no zincs fitted. Most engine mfg use copper heat exchangers which need a zinc to keep corrosion at bay."

I cannot speak for the QM series as I have no experience, but if it is a GM-F series don't worry about it. To my knowledge the only small Yanmars with zincs are the directly raw water cooled models.