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Detroit running warm

Discussion in 'Post Yacht' started by mwwhit1, Jul 16, 2018.

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  1. mwwhit1, Jul 16, 2018
    #1
    mwwhit1

    mwwhit1 Senior Member

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    I'm a bit embarrassed to post this. But hopefully it can help someone else. My port engine has been running a bit high at cruise for quite awhile. Despite cleaning the heat exchangers, it would get worse as the sea water warmed up. I know from boatdiesel about checking the exhaust shower head. (This behavior is typically a lack of water flow). Which I did by removing the exhaust hose and inspecting the spray holes. Checked from intake strainer through each piece to the exhaust over the years (except one!!).

    I finally decided to take the hose off that is attached to the exhaust. Very happy to see it blocked. I couldn't believe any water was getting through. 7 pieces in the port, 4 in starboard (that stayed at 175 at cruise).

    If you have the large zincs 3/4x3.5" in the heat exchanger, apparently the top inch breaks off at some point. (I need to change them more than once a year). It's worth the time to check. Temps were great this weekend!!

    Attached Files:

  2. Jorge Lang, Jul 16, 2018
    #2
    Jorge Lang

    Jorge Lang Senior Member

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    Unfortunately, exhaust systems are overlooked as being part of routine inspections. You headed in the right direction by going to the mixer to check for blockage. I would suggest that you look at the hose connection and for fiberglass discoloration as signs of overheating. Also, if you have black hose, I would suggest you upgrade to the blue silicon hose. This has an operating temperature of 350 degrees and is much easier to work with. You will also need to change the clamps as the wall thickness is less with the silicon hose.
  3. chesapeake46, Jul 16, 2018
    #3
    chesapeake46

    chesapeake46 Senior Member

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    (+) 1 for the blue hose
  4. mwwhit1, Jul 16, 2018
    #4
    mwwhit1

    mwwhit1 Senior Member

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    Agree. I did that several years ago. You just can't see it in the picture.
  5. Capt Ralph, Jul 16, 2018
    #5
    Capt Ralph

    Capt Ralph Senior Member

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    Sad thing about blue hose, you can not use it in a bend. Soft sided and will collapse.
    There is a wire spiral blue hose that is expensive as heck and looks funky.
    If you really have to have the smooth blue hose and have bends in it, go to a real plumbing shop (not Loosers or Homely depot).
    Fit their copper sweat on 90s or 45s to the hose your using. These will make your bends and look great.
    Solder on a bonding tab to it and plan a bonding wire to it. You can solder on a second tab and use it for a hangar point.
    Option; go to a chrome plate shop with them.
  6. PacBlue, Jul 16, 2018
    #6
    PacBlue

    PacBlue Senior Member

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    Aren’t there blue silicon hose elbows with molded in ribs for bends?
  7. Capt Ralph, Jul 16, 2018
    #7
    Capt Ralph

    Capt Ralph Senior Member

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  8. MBevins, Jul 16, 2018
    #8
    MBevins

    MBevins Senior Member

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    What is the life expectancy of blue hose. I have a short hose with formed elbow on my 6-71 that J&T custom made for their conversions. Of course they stopped making it and I have looked everywhere for a replacement when the engines were rebuilt.
    Seemed just wrong to re-hose the entire engine and leave that one unchanged. Mechanic said not to worry about it, I still do.
  9. Jorge Lang, Jul 17, 2018
    #9
    Jorge Lang

    Jorge Lang Senior Member

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    As long as you don't overheat and they are installed properly, they won't fail. As far as your short elbow hose, send me a photo with the dimensions, I might be able to source it for you.
  10. PacBlue, Jul 17, 2018
    #10
    PacBlue

    PacBlue Senior Member

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  11. Jorge Lang, Jul 19, 2018
    #11
    Jorge Lang

    Jorge Lang Senior Member

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    Those are the ones!!!
  12. Capt J, Jul 19, 2018
    #12
    Capt J

    Capt J Senior Member

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    In addition to the Trident ones which are female to female, you can also buy fiberglass 90's and 45's that are male to male for tight bends.
  13. Jorge Lang, Jul 19, 2018
    #13
    Jorge Lang

    Jorge Lang Senior Member

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    That didn't sound right!!!
  14. Capt Ralph, Jul 19, 2018
    #14
    Capt Ralph

    Capt Ralph Senior Member

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    I think Skippy J meant fiberglass formed 45 and 90 elbows. Male fitted to female hose.
    Usually perfect over 1 1/2" + hose.

    I have mentioned glass tubes in other threads but I do like the polished brass look.

    I still have the pics that Carl sent out long ago of a polished up 671. I wish I could find that thread.
    I may have to send back the pictures I copied.
  15. post46, Nov 12, 2018
    #15
    post46

    post46 Member

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    Is the short hose about 6 7 inch long in about 1 inch round if so I have found that short hose at Napa
  16. post46, Nov 12, 2018
    #16
    post46

    post46 Member

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    With that 90-degree hook in it
  17. Capt Ralph, Nov 12, 2018
    #17
    Capt Ralph

    Capt Ralph Senior Member

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    Your asking a question? Can you type slower and explain your thoughts and questions?