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Cat 3412E fresh water flush

Discussion in 'Engines' started by gcsi, Jul 28, 2022.

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  1. gcsi, Jul 28, 2022
    #1
    gcsi

    gcsi Senior Member

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    I’ve got a pair of Cat 3412E in my boat and am contemplating a freshwater flush of the seawater cooling circuit after use. My plan would be to remove a zinc immediately after the raw water pump and flush from there with a hose Bibb and city pressure off of a garden hose. While this will leave the saltwater circuit prior to raw water pump un-flushed, there are no expensive components on that side of circuit. Theoretically, all the other coolers / heat exchangers should flush.

    The shower heads are well downhill and away from the turbos. Additionally, the exhaust hose will not build any back pressure.

    Any reason not to do this?

    thanks in advance for any comments.

    Brett
  2. Pascal, Jul 28, 2022
    #2
    Pascal

    Pascal Senior Member

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    3412s are bullet proof. Yes you can flush them but not sure it s worth it.
  3. TahoeJohn, Jul 29, 2022
    #3
    TahoeJohn

    TahoeJohn Member

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    I went with a slightly different approach with my 3412Es (possibly stolen from @mapism, not sure). I drilled and tapped the thick bronze covers of the sea strainers and run fresh water directly into those, closing the intake seacocks (one engine at a time). Dock water pressure seems to be able to keep up with the raw water impellers with the engines idling. Works fine and just takes a few minutes if the boat is going to be idle for more than a couple days.
    20220729_082622_resized.jpg
  4. Capt J, Jul 29, 2022
    #4
    Capt J

    Capt J Senior Member

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    THIS. Totally unneccessary to fresh water flush most all diesels IMO.
    Fiammetta42 likes this.
  5. Tbill36, Mar 30, 2023
    #5
    Tbill36

    Tbill36 New Member

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    Please elaborate. I would think that any raw water aftercooled diesel could benefit from a fresh water flush. I even thought that the Cat mandate to replace their raw water cooled aftercoolers every 6 years did not apply to fresh water boats.
  6. bayoubud, Mar 30, 2023
    #6
    bayoubud

    bayoubud Senior Member

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    Not a bad idea seeing as how Cat thinks their AC's only last six years. Haven't heard of AC issues on the 3412's.
  7. Pascal, Mar 30, 2023
    #7
    Pascal

    Pascal Senior Member

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    I ran a pair of 2003 3412Es up to 5500 hours when the boat sold. The 3422s didn’t have any aftercooler issues.
  8. bayoubud, Mar 30, 2023
    #8
    bayoubud

    bayoubud Senior Member

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    I had 2002 3412's in a 50c Hatt that were great engines and boat.
    Last edited: Mar 30, 2023
  9. Capt J, Mar 30, 2023
    #9
    Capt J

    Capt J Senior Member

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    Aside from CATs with the aftercooler issues. Everything else goes several decades if not longer without any issues from having raw water running through them and sitting in them (aside from needing the coolers cleaned, which would be necessary even if you were running the boat in fresh water).