Broken Engine Zinc (anode)

[mjohnh]

I just had a telephone call with a mechanic hired to change the timing belt and zincs on my Yanmar 315. One of the zincs broke, so he abandoned that and is concerned about it having to be "drilled out" and debris going into the engine.
Any suggestions???????

[Tree]

It will erode out on its own in time I would have thought - my zinc broke off in my intercooler so I drilled and tapped a hole in it so i could pull it free. Soon as i started to drill it, it became free and stuck on the drill bit. Came out as once piece!

[RobS]

Oh my, the mechanic called the owner because of a broken zinc?
If he drills the zinc the debris is only zinc?
Are you sure you got the whole story?
Which cooler, which zinc? Some are easily accessed by removing hoses or caps, some are not..
Don't let him simply push the broken zinc into the cooler and leave it there, the flow of raw water will cause it to bounce around and damage could be done to the tube ends.

[Tree]

I wouldn't think the zinc will damage the copper tubes - it's pretty soft and will be considerably softer after it's been in the cooler for a while. Consider how often you find zincs in the cooler ends that have broken away naturally? I'd be more concerned about it blocking the stack especially if you haven't rydlymed your system or cleaned the stacks for a few years.

Personally for me, if I had a mechanic that abandoned a job because of something quite straight forward, I'd be looking for a new mechanic.

[RobS]

I wouldn't think the zinc will damage the copper tubes - it's pretty soft and will be considerably softer after it's been in the cooler for a while. Consider how often you find zincs in the cooler ends that have broken away naturally?....

I don't make this stuff up

[Tree]

What was that zinc made of, titanium? Mine have all crumbled in my fingers!

[mjohnh]

Saga continues.........Hired another mechanic from 40 miles away....on the Yanmar website as being a Yanmar dealer.....they sent a mechanic.....said he could not change the zincs as he could to get to them.....wow......big demand for good mechanics in SW Michigan!!!..............so....suggestions are welcome........my boat will be hauled out in 3rd week of October.............I am average at best when it comes to mechanical skills.....I have never chanced zincs....I have never "drilled" any ..............I can follow directions....I can turn a wrench.......1. should someone like me try to change them? 2. How hard are they to get to....really? 3. What tools do I need...anything special? 4. If one or more need to be "drilled" what size bit do I use and can I get a cordless hand drill to them; or, do I need a special drill?...5...Does anyone have "step by step" directions on how to do this.....mine is a 6LPA in an engine box model.........ANY SUGGESTIONS ARE WELCOME............ANXIOUS ABOUT ANODES.....THANKS IN ADVANCE

[special k]

with my 6lpa-stp engine box the anodes are accessible but not easy. had one come off the brass nut on the intercooler but it stayed until it deteriorated. no special skills or tools needed to swap out your zincs. if you want to hurry the deterioration of the zincs try a rid-lyme treatment to help clear your coolers.

[gcmarshall]

Saga continues.........Hired another mechanic from 40 miles away....on the Yanmar website as being a Yanmar dealer.....they sent a mechanic.....said he could not change the zincs as he could to get to them.....wow......big demand for good mechanics in SW Michigan!!!..............so....suggestions are welcome........my boat will be hauled out in 3rd week of October.............I am average at best when it comes to mechanical skills.....I have never chanced zincs....I have never "drilled" any ..............I can follow directions....I can turn a wrench.......1. should someone like me try to change them? 2. How hard are they to get to....really? 3. What tools do I need...anything special? 4. If one or more need to be "drilled" what size bit do I use and can I get a cordless hand drill to them; or, do I need a special drill?...5...Does anyone have "step by step" directions on how to do this.....mine is a 6LPA in an engine box model.........ANY SUGGESTIONS ARE WELCOME............ANXIOUS ABOUT ANODES.....THANKS IN ADVANCE

All you should really need is a spanner or socket. I was to change mine today, but the sea was surging a bit much, so I didn't want to stay long at the dock.

I plan now to do it next week Saturday. I will try to take some pics, and post back. It's not too hard. Mine is a 6LPA in the flush deck - I would imagine yours are easier to get at than mine. The zincs can be a bit hard to spot the first time.

[mjohnh]

gcmarshall.......Terrific...thank you so much!!!.....this may help a lot of folk on this forum......wonder if you should post your work pictures to documents too.....not sure how to do that, but maybe they should be archived....

[gcmarshall]

mjohnh - I changed all the zincs on Sat. In theory it's an easy job. In practice, it can be a pain due to the positioning of some of the zincs. I took some pics, and will post in a day or two once I have time.

[gcmarshall]

Replacing Zinc Anodes in a Yanmar 6LPA-STP

I am a bit of a novice, so apologies for any errors or bad advice I may give. Corrections or comments are appreciated.

I have 6 “pencil zincs” in my yanmar coolers/heat exchangers, and they are generally easy to remove with the correct spanner or socket.

Fuel Cooler – Accessible through the front-port hatch. This is an easy one to take out. As you can see, it still looked good, and I just cleaned it up, and re-installed.

Fuel Cooler 1.jpg

Fuel Cooler 2.jpg

Freshwater Cooler #1 – On the starboard side of the engine. This has two zincs. One is easy to get at, and one not so much. The one on top is easy to remove with a socket. This had no zinc left in it, so I may have to check this one a bit more often.

Freshwater Cooler 1.jpg

Freshwater Cooler 2.jpg

Freshwater Cooler #2 – This zinc is on the rear end cap of the cooler. It is not obvious from the pic, but this zinc is very difficult to get at, as I think it is the turbo which is limiting access. However, by removing two nuts holding the cooler onto the engine, and removing the raw water hose as shown in the pics, we can ease it up an inch which is enough to do the job. This one is a 2 person job. It would be easier if we could remove a short coolant hose, but I didn’t want to have to refill coolant unnecessarily.

Freshwater Cooler 3.jpg

Freshwater Cooler 4.jpg

Freshwater Cooler 5.jpg

Freshwater Cooler 6.jpg

Freshwater Cooler 7.jpg

Oil Cooler – To access this zinc, you need to get down inside the boat, behind the gear box, and look up on the port side of the engine. You can see the air filter on the right hand side. This is an easy one to change with a socket.

Oil Cooler.jpg

Oil Cooler 2.jpg

Oil Cooler (2nd one) – This zinc is on the port side of the engine, next to the oil filter, accessible via the side bunk. Another easy one to change.

Oil Cooler (2nd).jpg

Intercooler – This zinc was hard to find at first. This is a larger zinc than the rest. And you need a 7/8” spanner with the usual slight angle in the spanner neck. It’s impossible to get a socket on it as there is no ceiling to work with. Once you have the right spanner, it’s not too bad.

Intercooler 1.jpg

Intercooler 2.jpg

A couple comments
Sometimes what remains of the zinc can fall off the bronze head inside the hole – sometimes a needle nose pliers can be handy to remove any remnants in the hole.
Be careful to reinstall zincs by hand at first, so there is no cross threading!
I have read not to use any kind of sealing compound or tape thread on reinstallation as you want the metal to metal contact for the zinc anode to be effective.
The generic zinc replacements I bought were about 1 cm too long, so I had to cut off a cm with a hacksaw. I also find on this engine that after tightening, there are still a lot of threads exposed. This is normal. Don’t overtighten.
I tend to check these zincs every 3 months, but I may adjust this as they wear at different rates. Two of them were completely gone!
In cleaning the old zinc anode heads for reuse, muriatic acid works well to eat out the old zinc, so a new one can be screwed in.

[mjohnh]

What you have provided is very much appreciated. I suspect that several owners will benefit from this. Did you have to "drill" any broken zincs? Not sure how to do that; or, what tool to use.......I suspect that means that a zinc broke and the "drilling" was to get the part out that remained. Maybe it can be "punched" or some other method.....don't really see how anyone could position a drill on some of those locations. Thanks again.....

[RobS]

Great job Gary!

Here's some additional info & pics in a topic I started on another forum. If you're not registered you should, it's free..

https://www.sbmar.com/community/topic/p ... c-install/

[gcmarshall]

What you have provided is very much appreciated. I suspect that several owners will benefit from this. Did you have to "drill" any broken zincs? Not sure how to do that; or, what tool to use.......I suspect that means that a zinc broke and the "drilling" was to get the part out that remained. Maybe it can be "punched" or some other method.....don't really see how anyone could position a drill on some of those locations. Thanks again.....

I'm not sure what could have been meant by drilling. In Rob's link he has a pic of using a vice grip and making sure the zinc is in really tight. I had a couple cases where the zinc did unscrew, and I screwed the head back into the zinc (Rob describes how he made a tool for this purpose)

I am sure there is plenty of ends of zinc that do accumulate in the heat exchanger caps, and are only accessible by removing the end caps.

Another way to deal with this is to run something like barnacle buster or rydlyme through the heat exchanger. This will dissolve the build up of lime etc... in the heat exchanger, and should dissolve any zinc anodes in there as well. I am trying to design something that I can connect to the raw water plumbing, using a bilge pump, to recirculate through the system periodically and clean everything. I bought some sulfonic acid for this purpose ( I can't get bb or rydlyme locally, and based on my research sulfonic acid should do the job well without harming seals/rubbers)