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CAT Aftercooolers — and whats Real

Discussion in 'Engines' started by luvtocruise, Jun 24, 2021.

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  1. Capt J

    Capt J Senior Member

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    Mapism, what I mean when MAN aftercoolers are isolated. They do not touch any other metal parts of the engine. They have a big rubber o-ring that seperates them.
  2. Capt Ralph

    Capt Ralph Senior Member

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    Why, It is probably to Cats spec and they sell a lot of air coolers.
    Further, They have a denial path on extended warranty claims.
  3. mapism

    mapism Senior Member

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    I know that's what MAN suggests.
    My point was that I've yet to come across one single MAN installation where this was actually the case.
    And I'm not saying this just because by sight they didn't look isolated - I checked them with a multimeter.
  4. mapism

    mapism Senior Member

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    Do you mean their cores? I can't see how they could be isolated, being bolted to the external box.
    Which is indeed bonded with the rest of the engine, and in turn with the rest of DC ground circuit.
    At least, that's what I found in many boats where I actually checked that with a multimeter.
    In spite of what MAN recommend, as I said.
    Last edited: Jun 26, 2021
  5. mapism

    mapism Senior Member

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    That's a very good point indeed.
    On top of that, I have a funny feeling that Cat aren't really interested to invest in their marine segment.
    Not as much as they used to, anyway.
  6. bayoubud

    bayoubud Senior Member

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    Requires separate DC grounds back to a DC bus. No DC grounding to the engine. Bonding wire from engine and any isolated raw water components such as thru-hulls and strainers to the transom zinc plate. Many builders probably don't wire engine isolated grounds because of added cost.
  7. Slimshady

    Slimshady Senior Member

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    The new c32 B motors are zincless. Hopefully they finally got the issues resolved.
  8. Capt Ralph

    Capt Ralph Senior Member

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    With that monkey-metal solder, I wonder if it was the zincs eating up that less noble material?
  9. TahoeJohn

    TahoeJohn Member

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    My 3412e engines (2001) run coolant through the ACs, but I believe that other versions of this same engine run raw water. I don't know when that change was made, but the Cat tech I had on board once was very surprised to see the fresh water ACs. Obviously the tradeoff is less corrosion using coolant vs running 50-80 degree raw water (instead of ~180).
  10. Capt Ralph

    Capt Ralph Senior Member

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    DDC does the same for it's older after coolers, (Not inter-coolers). The freshly cooled coolant goes thru your AC before it goes to back to cool the engine.

    I wonder if Cat still offers the parts in volume to back date current designs.

    What I would give to make an after market kit like that. The design patients have long run out.
  11. 993RSR

    993RSR Senior Member

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    The manual does not reflect the future service bulletins. Replace the aftercoolers every 6 years regardless of hours. Some owners flush out the raw water side with fresh water when the boat will be idle for weeks which extends the life. Still I would replace them at 6 years or certainly in the 7th. Less running is more harmful to seals and O rings.
  12. bayoubud

    bayoubud Senior Member

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    Flushing often with freshwater should help them live longer, plus keeping the drains clean. Manual also says to pull, clean and inspect aftercoolers every two years. I would stretch that to 3 years and not do again if replacing in six years. Cat needs to design an aftercooler with the right metal that will last same as other mfg.'s. I have had two boats with Mans, the aftercoolers on both lasted over twenty years.
  13. LuvBigBoats

    LuvBigBoats Member

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    I don't think this is too off topic--would a freshwater flush help on the 3406 a/cs given their location and/or the fact that the flush would occur when the boat is in idle at the dock? Is there a thermostat that could prevent the fresh water from reaching the a/cs when the boat isn't running hot or would they get a good flushing regardless of engine temp?

    Had put flush system on my Cummins QSCs and thought it helped a lot.
  14. Pascal

    Pascal Senior Member

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    Cat did just that on the 3412s...
  15. mapism

    mapism Senior Member

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    Not 100% sure about 3406, but normally the thermostat opens/closes the circulation of closed cooling circuit, not of raw water.
    I never came across an engine where the raw water path was restricted/deviated in any way.
  16. Capt Ralph

    Capt Ralph Senior Member

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    I wonder about the chlorine in the tap water. No way to get it all out.
    Volvo had a salt rinse system for a while, I wonder it that would help.
  17. LuvBigBoats

    LuvBigBoats Member

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    Makes sense, thanks
  18. TahoeJohn

    TahoeJohn Member

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    Agreed. I would think that the exhaust will need this raw water cooling almost immediately, long before the engine itself comes up to temp...
  19. rtrafford

    rtrafford Senior Member

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    On areas of high water flow, like HVAC etc, I've introduced a bronze tee in line of the hose just ahead of a heat exchanger or sea strainer, bonded it to the next member in the metal chain, and used the tee to mount a pencil zinc to help cut down on longevity issues.
  20. bayoubud

    bayoubud Senior Member

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    I've never owned a boat with zincs in the ac system, definitely a good idea.