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Soot exhaust leak

Discussion in 'Technical Discussion' started by Dan balmer, Jan 5, 2020.

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  1. Oscarvan

    Oscarvan Senior Member

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    You could get a point and shoot thermometer. Set a base line, compare P and SB. Check them once in a while at similar operating temps. If it starts getting hot around the edges of the insulation or develops (much) hotter spots you can assume something's going on in there....
  2. cleanslate

    cleanslate Senior Member

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    Was working on my Yacht today ...40 year old Ocean Yachts that is :).
    Took the semi-soot stained blanket off my Dawg and was able to pull off chunks of old iron from the bottom of the original J&T cast below at the round flange connection to the Turbo exit side .

    Do you think it's time I change it out ?! :rolleyes: 40 year old elbow.
    Yes I did the starboard side three years ago.
    My boat is a restoration in use vessel. Keep on using it and replace things as I go along. I love ito_O
  3. Beau

    Beau Senior Member

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    Thanks. Will do. I used to casually inspect the systems. I will now examine them more closely. Thanks Dan for raising the issue.
  4. Capt J

    Capt J Senior Member

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    Yes, replace. If you're getting soot on the blanket you have an exhaust leak. If chunks of old iron are falling out of the cast elbow, it's shot.
  5. mapism

    mapism Member

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    I'm also a fan of the "if it ain't broke..." principle, generally speaking.
    But removing the shrouds after 22 years for a decent visual inspection sounds pretty reasonable, to me.
  6. Capt Ralph

    Capt Ralph Senior Member

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    Beau
    Are your risers cast iron or stainless?
    I've always noticed nice stainless cans on the MANs.
    You may see a water leak before an exhaust leak with the shinny dawgs.
    Last edited: Jan 27, 2020
  7. Capt Ralph

    Capt Ralph Senior Member

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    Chunks of iron or just bigassed rust flakes?
    I remember a member a while back that replaced a iron mixer with the updated stainless unit but had a hose connect problem. Before you take it apart, take a bunch of pictures to your J&T shop to make sure it's a real plug & play.
  8. Beau

    Beau Senior Member

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    They are stainless and I see nothing evidence a leak.
  9. Capt Fred

    Capt Fred Senior Member

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    These guys make a replacement in cast stainless steel elbow that looks much superior to the original cast iron or a welded stainless mixing elbow and very inexpensive compared to the competition. https://hdimarine.net/
  10. Beau

    Beau Senior Member

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    On their opening page they are showing bronze elbows for a SS mixer, Is that good? Mine are all SS, if my memory is correct.
  11. Capt Fred

    Capt Fred Senior Member

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    I'm not the expert there but it comes with a real thick gasket and I don't think that joint is wet except when running. I do share your concern and wonder why that part is not stainless. Probably worth asking their opinion and others on yachtforums will likely offer advice.
  12. Capt Ralph

    Capt Ralph Senior Member

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    Yours was made for your engines with the boat install in mind. All custom welded stainless.

    HDI makes replacements without any custom thoughts. Including not knowing what hose size will be used at the dump can or what direction the hose needs to be pointed.

    Bronze will work just fine with the cast stainless.
  13. Beau

    Beau Senior Member

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    good to know
  14. cleanslate

    cleanslate Senior Member

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    What's a dump can? Other than the one we all already know about....:eek:
    What's it purpose such as inline DD71s? and others?
  15. motoryachtlover

    motoryachtlover Senior Member

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    Far from an expert my understanding is that the main function of the dump can is to cool the exhaust gasses so they can pass through the fiberglass tubing and “rubber” hoses as the exhaust exits the boat. I replaced mine as the yard was in there doing major work and the yard said the spray ring holes were becoming corroded. They said I had about 5 more years but I replaced them since access was available. I never saw any evidence of soot on mine.
  16. cleanslate

    cleanslate Senior Member

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    Ok , so all combustion gas is passed through the turbo and out the elbow? With the elbow being water jacketed with a ring collar with holes in it spraying at the exhaust gas after the turbo within the elbow... ? This is where all the the cooling water comes from out the stern exhaust pipe ? The only source of water out the exhaust pipe ?

    I do know if the elbow cooling water holes get clogged up you can have a big problem and or fire from all the heat generated there.
  17. Capt Ralph

    Capt Ralph Senior Member

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    Usually before the hoses and tubes start melting and burning, somebody noticed the engine temp going up.
    If raw water does not go thru the whole engine systems, it over heats.
    This is the big question if water is coming out your exhaust, one; pumping water? two; pumping all the water? If the riser, mixer, dump can is restricted, the motor gets warm/hot/overheats.
  18. Beau

    Beau Senior Member

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    Check out the website at post # 29 for a visual of a replacement set up?
  19. mapism

    mapism Member

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    Nope. The main function of dump cans is to silence the exhaust.
    The possibility to use rubber hoses after the dump can is just incidental, sort of.
    In fact, also u/w exhausts (where there's no can) have at least one section made in rubber, to avoid transmitting engine vibrations to the hull.
    Of course, that can only be done after the raw water re-injection point, because the initial dry section right after the turbo can get red hot.
    Which is the reason why it's covered with insulation, but that applies to both u/w and can exhaust systems.
  20. Capt Ralph

    Capt Ralph Senior Member

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    Are you referring to a water-fall or flooded muffler can? Confusing it with a riser/mixer/dump can?