Check those exhaust tubes

Discussion in 'Downeast Engine Room' started by backman, Jan 16, 2020 at 6:11 AM.

  1. backman

    backman Captain

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    As part of winter maintenance we proactively replaced my 10 year old/5000 hour black exhaust tube with a new blue silicon one. I had noticed cracks on the outside the past season, look what the inside looked like!

    it’s a QSM 11 engine and at idle after a couple hour run the top of the tube was about 220 degrees with a heat gun...
     

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  2. ARC

    ARC Senior Member

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    Why was the hose that hot? I can always touch mine without pain.
     
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  3. Genius

    Genius Captain

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    Bad shower head design. TA talks about it on seaboard marine's website. One size doesn't fit all.
     
  4. WoundUpMarine

    WoundUpMarine Captain

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    I looks like that mixer is almost horizontal going aft. When the engine is idling, less water is being pumped. Heat goes up and water goes to the bottom of the mixer. Maybe a new designed mixer isn't a bad idea.
     
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  5. Blitzen

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    I found this interesting on my Scania, the size of the holes. This works well. engine exhaust mixer.jpg
     
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  6. Genius

    Genius Captain

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    besides the hose issues. This design is a wet jacket design which is not best practice. No dry riser doesn't help either. No pitch. ugh. Sorry, but it will save you problems in the future if you correct these items.
     
  7. WoundUpMarine

    WoundUpMarine Captain

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    John, did you ask anyone about the reasoning behind having smaller holes at the top? I would have thought it would have been the other way around, cause a restriction low to force water towards the top of the mixer.
     
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  8. Genius

    Genius Captain

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    yeah, seems upside down?
     
  9. Blitzen

    Blitzen Captain

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    This is the mixer that was supplied with the engine. Every install is unique and needs proper attention. Here is the arrangement we went with, spill over point is 24 inches above the waterline and all water is on the down stream side of the exhaust. Riser by Tim Toppins and has since been hardcoated. Exhaust 1.jpg
     
  10. Genius

    Genius Captain

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    why is the drain at the top?
     
  11. Blitzen

    Blitzen Captain

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    I thought so too but it actually makes more pressure at the top to give a better spray pattern. didn't believe it until I saw a video of it in action. There is a tremendous amount of water flowing through the system.
     
    Last edited: Jan 18, 2020 at 8:27 PM
  12. Blitzen

    Blitzen Captain

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    That is not a drain.
     
  13. Genius

    Genius Captain

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    what is it?
     
  14. Blitzen

    Blitzen Captain

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    Back pressure test port.
     
  15. Genius

    Genius Captain

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    Shouldn't that be on the dry side?
     
  16. Genius

    Genius Captain

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    interesting!
     
  17. Blitzen

    Blitzen Captain

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    You got me there, maybe I am wrong. Always had a plug in the elbow to test back pressure but your logic sounds right.
     
  18. Genius

    Genius Captain

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    sometimes a tell tale is run to make sure raw water is flowing. Run over the side into a thru hull fitting above the water line. Maybe it is a port for that?
     
  19. Blitzen

    Blitzen Captain

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    Well I am going to look into that a little further and see what the answer is. I am sure Tim could answer the question right quick. I will report back with an answer.
     
    Last edited: Jan 18, 2020 at 8:45 PM
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  20. WoundUpMarine

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    It could be a bung welded on both sides, so still used for back pressure. I'm going to modify the mixer for my volvo to take a EGT probe that way. Or it could be a drain, hard tellin not knowin.
     

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