zincs in my yanmar 4LHA-DTE

Discussion in 'Downeast Boat NEWBIES' started by samneedsaboat, Apr 25, 2018.

  1. samneedsaboat

    samneedsaboat Member

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    Hi all,
    I was exploring the engine with my neighbor (former Coast Guard diesel chief) and he pointed out the zinc locations on the oil cooler and several other spots. I loosened one of the cap screws and the anode unscrewed from it an remains in the hole...common? solution? I tried to lightly coerce it from its perch with a needlenose without damaging the cast threads without success. Looking for some advice before the surgical tools come out.
     
  2. JimRP31

    JimRP31 Captain

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    Break out the surgical tools by that I mean a longer needlenose pliers or surgical tweezers. I had the same problem and with a little patients they all came out.
     
  3. djmarchand

    djmarchand Captain

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    Or just pull off the end cap and pull out the zinc remnants. A shop vac will sometimes suck it out if you can open an alternate air path. But that is probably as difficult as removing the cap.

    When you replace the zinc, tighten it with pliers so it will not unscrew. I even put a dab of nail polish around the circumference of the zinc near the end cap so it will not corrode there. Also replace the zincs before they get too bad, about 1/3 gone is about right.

    David
     
  4. samneedsaboat

    samneedsaboat Member

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    Thanks, I just wanted to make sure there were no surprises. By the way, how often do you change them out? I've seen postings that some folks do it twice a year?
     
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  5. fortier256

    fortier256 Captain

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    Interesting. I have a 4lhdte and there are no zincs in that motor. Is this the engine or the gear oil cooler that you are referring to?
     
  6. samneedsaboat

    samneedsaboat Member

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    Here are a couple pics. 2 on one end and one on the other
     

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  7. fortier256

    fortier256 Captain

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    Sam yours is a 4LH “A” DTE? That must be the difference. Yours was assembled in the US by Mack Boring I believe. Mine has no “A” and assembled in Japan.....the way I understand it.
     
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  8. djmarchand

    djmarchand Captain

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    The A model Yanmars were assembled in the US by Mac Boring with some US sourced parts. That is why you may have zinc fittings on an A and not a Japanese model. Yanmar has a rather strange view of the need for zincs. The JH engines have no zincs and from what you say the Japanese assembled LH engines don't either. I prefer zincs on all heat exchangers.

    David
     
  9. ThePartsGuy

    ThePartsGuy Senior Member

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    We recommend pulling one or two zincs out in the middle of the season to determine zinc fall off rate. Most of our customers are on a spring time annual replacement schedule. It's not a bad service idea to pull the end covers off the coolers and look for zinc debris every couple of years. Impeller pieces or anything else like marine growth or seaweed could lead to water flow restriction. There are a few gaskets you will want to have before you take the end covers lose. Contact your local Yanmar dealer. They should have them on their shelf. If not drop me a PM. We stock them here.
     
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  10. samneedsaboat

    samneedsaboat Member

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    Thanks for the information, I dug through the paperwork last night and found the service records from last summer which was when the zincs were replaced. Also found the original paperwork from Mack boring at the time the boat was re-powered. New Question: got a name for the local Yanmar parts dealer? Southern RI
     
  11. Genius

    Genius Captain

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  12. cb38

    cb38 Member

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    we change zinks every oil change about 3to4 times a year
     
    cb38,
  13. fortier256

    fortier256 Captain

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    I’m feelin a little left out here. I suppose I’ll have plenty to do when my engine dissolves.
     
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  14. Genius

    Genius Captain

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    LOL. Strangely enough, I've never had a boat engine of my own that needed zincs. The first volvo KAD44 had nothing...but a very robust saltwater side. The 4LH-DTE that also has no zincs. The work boat has a 6BTA, but....it's keel cooled so no saltwater or zincs.
     
  15. TCL

    TCL Senior Member

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    If the cap comes off leaving the core you could either remove a hose and then push it in to the cooler to remove or a better way is to take a cap and grind off the threads then screw it back on to the core to then pull it out.

    There always seems to be one zinc that disintegrates faster than the others I just replace them all at that time which for me is in the spring I run the engines on the hard to flush out the antifreeze then do the zincs.
     
    TCL,
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  16. 05bill

    05bill Captain

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    how about rydlyme ?
     
  17. Diesel Jerry

    Diesel Jerry Captain

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    I don't know if you DYI'ers would benefit from this but I always put the year on the zinc plug. Maybe for some of you guys in the high annual hour bracket could put the full date? I also put a small touch of Teflon on the zinc plug...and wait for that debate.
     
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  18. Ben Zehnder

    Ben Zehnder Member

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    The Yanmar 4lha service manual is downloadable online and shows the zinc locations. I replace every Spring and it seems that where there are two zincs in the same system one sacrifices before the other. I chalk this up to a location closer to the charge.
     
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  19. TCL

    TCL Senior Member

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    Ben,
    I have the same issue with my 6LY's. 2 zinc's 3" apart in the same heat exchanger, 1 disintegrates faster than the other...I was told that the difference is the way the water flows through the system.

    Also, I agree withe Jerry only I use plumbers putty on my zinc threads...I hate to over tighten them. I also use a very small round wire brush to clean the treads before inserting the new zinc.
     
    TCL,
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  20. Ben Zehnder

    Ben Zehnder Member

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    Not to hijack the thread, but if only my prop nut zinc would stay on for the season.
     

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