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Soot exhaust leak

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

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  1. mapism

    mapism Member

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    I guess that flooded is the more appropriate description for the cans I was referring to.
    Are there other types of exhaust cans which don't stay flooded while both the gas and the raw water flow through them?
  2. Capt Ralph

    Capt Ralph Senior Member

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    Maybe some extra muffler designs but there will still be a water/exhaust gas mixture going thru it.
    The only design that I can think of you did mention, Thru the hull straight down.
    There will still be a riser/mixer/dump can to mix and cool the exhaust as the gasses are diverted to & pushed down below the water line. Usually there is a small tube venting above the water line to help the engine idle and it will still have it's own wet muffler.

    Dry stacks don't use water but release their exhaust gasses high above. They have dry cans (muffler/spark arrestor/scrubber).

    Now I'm no expert.
    Send me a picture or sketch of what your thinking of and I'll figure it out and learn something.
  3. mapism

    mapism Member

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    Well, I wouldn't call myself an exhaust expert, either.

    I just thought to answer post #35 from MYlover, because gas temperature is cooled down by raw water injection, regardless of whether there are also cans or not.
    And typically, while there are no cans in underwater exhausts (unless you call cans also the raw water injection hoses), they are often used with transom exhausts above the w/line, because they would be very noisy without them.
    Therefore, it's silencing rather than cooling the main purpose of cans, AFAIK. That's all I meant.

    Ref. dry stacks, yep, of course they are radically different, often coupled with keel cooling, etc.
    But I don't think anyone had dry stacks in mind, in the context of this thread.

    Sorry, I don't have any drawings, and can't think of where to look for one.
    I did read a very interesting article about pros and cons of different marine exhaust on PBB magazine, many years ago, but don't ask me to find it...
  4. cleanslate

    cleanslate Senior Member

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    Ugh..I'm up early again. This getting old thing really stinks!
    Anyway, yes thanks. Now I see how it works and how my turbo works. I did not know I have two squirrel cage whirlygigs in the turbo...one to push clean air into the cylinder / motor...one to exhaust the combustion exhaust which drive the turbo..I believe.
  5. Capt Ralph

    Capt Ralph Senior Member

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    I believe mylover was referencing his water injection cans, (dump cans).

    Yes, I have been all along.


    I'm a long subscriber, I'll try to look it up some sleepless night.
  6. Capt Ralph

    Capt Ralph Senior Member

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    Up early, nature call or back up late pending going back to sleep (maybe, hopefully)?
    Yep, this old thing dose really stink.

    I'm having issues with Gravity also.
    !cid_D67BCD71C9AA4BD0B39DAFAB273D895D@DESKTOPA25L25J.jpg
  7. mapism

    mapism Member

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    Aha, I see. I wasn't aware that water injection along the exhaust are called dump cans, so I assumed we were talking of flooded cans.
    Which sometimes I heard described also as "dustbin style" silencers, just to mention another way to describe them,
    Anyhow, nomenclature clarified now, thanks!

    PS: I sympathize with your troubles with gravity.
    As a well known compatriot of mine, the Architect Renzo Piano, used to summarize a lifetime spent designing outstanding buildings:
    "I always enjoyed trying to defeat gravity"... :)
  8. Dan balmer

    Dan balmer Member

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    Just wanted to give everybody an update on what I discovered with the exhaust soot leak. I removed the exhaust system by removing a slice blanket to reveal a stainless bellows section with special v clamp that was removed. I then unbolted both turbo flanges and removed the 2 sections of exhaust system and put on the tailgate of the pickup and took cutoff wheel and neatly trimmed 3” off end run of Hardcoat insulation at the juncture to the mix can and discovered an unbounded weld line on the crown weld that allowed a small raw water leak to saturate the insulation end up about 2” to the weld that connects the can to dry part of exhaust and over time corroded out that weld which then allowed dry exhaust soot to pressurize the hard coat insulation assembly and exit at any tab or probe or end run of the insulation. Anyway noticed as well that design of the mixing can and it’s placement allow s total drainage of can when engine turned off Anyway I had weld shop reweld the can onto the dry exhaust pipe section and reweld the crown weld on the mix can. I then carefully reposition the insulation section and sealed the joint and with high temperature mortar caulking used by wood stove and furnace people and comes in caulk tube and dries black the same color as Hardcoat. Anyway I am going with this repair method for $150 bucks I got new gaskets and v clamp from marine exhaust systems in fla I also discovered that the engine air filters were impacted with soot so that even though the leak was minor it over time starved the engine. Not good !
  9. Capt Ralph

    Capt Ralph Senior Member

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    Change all engine oils ASAP.
    Carbon in the engines is bad news.
  10. Dan balmer

    Dan balmer Member

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    Sent out oil for analysis and came back with no appreciable soot but an alarming amount of iron Aluminium and some chrome as compared to the other engine They recommend checking air clean ers and exhaust which I am doing. Had FDDA remove injectors and boroscope all 8 cylinders and discovered on this engine with 3200 hrs no indication of broken rings or cylinder parts but a lot of rust and condensation from sitting around. The crosshatching was still evident. Had injectors tested and were not popping according to spec according to nozzle master what ever that means. Anyway having new MTU injectors installed on that engine The previous owner in 2016 had replaced them with remans in south Florida about 400 hrs ago so don’t know what I’ve really got so going with new ones FDDA says do not use remans injectors in marine engines. I am wondering if I should get them for the other engine as well. The engine s do not reach full rpm especially the port engine which is why I am digging into all this and getting to the bottom of it engine wise first before I remove the props and take pitch off them. I know that this is a lot of information but while I have your attention wanted run it by you all
  11. Capt J

    Capt J Senior Member

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    It sounds to me that water is leaking down your exhaust and that is leading to the high metals given the situation. I would have a new riser made and not fix the old one.

    That being said, how often are the engines run and how long are they run for? Do you start them a minimum of every 2 weeks and let them run to temperature?
  12. Beau

    Beau Senior Member

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    Also when I store in the winter I put plastic bags over my air intakes/airseps, and small plastic buckets in my exhaust outlets, some people use a balls. I also keep the engine heaters on.
  13. Dan balmer

    Dan balmer Member

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    I think that is part of the problem they just sit up on the hard for 6 months in port Canaveral with the exhaust openings and dual air filter openings next to huge air boxes that are a conduit of humid air to the cylinders and then the rig is launched and the stern is back against a concrete seawall 8’ high and 4’ away Fromm the exhaust exits and sits some more without use. Anyway I am going to come up with an improved storage system of blocking the openings to the engine and blocking the air boxes and installing dehumidifier in engine room during storage season and then of course when launched activating engine every week. By the way what prevents me starting the engines on the hard every now and then with raw water cooling belt off?
  14. Beau

    Beau Senior Member

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    you'll be spinning your impeller dry? Unless they are driven by that belt. Most impellers are mechanically driven, I think. No maybe not now that I think of my genny.
  15. Capt Ralph

    Capt Ralph Senior Member

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    Were the cylinder valves and seats inspected? Rust on valve seats may not clear and the seat burns out.
    Yes, you have dock queen syndrome. Ya got to go fishing and run them lil puppies.

    Make sure new injectors are popped and matching. This is important...

    Turbos may be a lil weathered also. When you replace all air and block filters, go for a run. If the turbos are a lil slow, a good run will help. Watch exhaust for dark at cruising rpm.

    Don't be in a hurry for WOT for about 30 min at cruise, then run them just a minute at WOT to compare previous rpm readings.
  16. Capt Ralph

    Capt Ralph Senior Member

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    I know the weather has sucked in your area. Lock is down and only place to run is outside pending weather.
    Be patient and safe.

    Dock side running of an engine sux IMO. The engine will never come to temp.
    New thought some of my customers do, start and run for 30 seconds. Clears the cylinders and splashes fresh oil around. Never gets warm to produce more condensation.
  17. Dan balmer

    Dan balmer Member

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    The FDDA tech didn’t mention anything about the valves. Don’t know whether they looked at them or not They seem to be satisfied with finding so much condensate and rust stain lines at the piston circumference line that that was the culprit that was causing the wear metal in the oil when the engine is run would scrape into oil as it went up and down to clean it off. I n regard to my other question about the injectors and get new ones instead of remans don’t the new ones come set up correct with out the need to test? I n regard to starting the engine on “hard” the water pump belt would be off. It has its own belt
  18. Capt Ralph

    Capt Ralph Senior Member

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    New don't mean donkey drops. Matching new or rebuilt is what is needed.
  19. Capt Ralph

    Capt Ralph Senior Member

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    Run just for that 30 seconds with belt off once a month on the hill. 30 seconds with belt on in the water.
  20. Dan balmer

    Dan balmer Member

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    I m confused I was under the impression that new injectors from MTU part number whatever they say for that engine at $450 ea. Were the genuine article of choice The FDDA people say this is the way NOT. reman of any kind