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Shaft whine

Discussion in 'Technical Discussion' started by ddw1668, Jan 30, 2014.

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  1. ddw1668, Jan 30, 2014
    #1
    ddw1668

    ddw1668 Senior Member

    Joined:
    Jan 18, 2007
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    Location:
    Murrells Inlet, SC
    Just finished a cruise from FL to SC and was reminded daily how loud my shafts 'whine'. Have repacked the boxes, aligned the shafts, and replaced the cutlass bearings and it changed nothing.

    The shafts are 2", 19' long, turning 31" five blades. Any ideas?:(
  2. CSkipR, Jan 30, 2014
    #2
    CSkipR

    CSkipR Member

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    Are you sure its not the props. I had a whine and a prop shop made a small adjustment on the tips and the wining went away.
  3. Capt J, Jan 30, 2014
    #3
    Capt J

    Capt J Senior Member

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    Do you have Detroit Diesels with turbo's? Did you do a lot of running at 1000 rpms and under for several days without running them up to cruise? If so it's in the turbo's. Run them at cruise for a good hour. I had this same issue, even hauled a boat, and the running gear was perfect, changed the cutlass bearings anyways, and the issue was still there, ran at cruise for a few hours and the issue was gone. It would come back if the engines did slow speed for an entire day.
  4. K1W1, Jan 31, 2014
    #4
    K1W1

    K1W1 Senior Member

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    Hi,

    I can answer that.

    This guy has marinised MACK Truck engines in his boat.
  5. ddw1668, Jan 31, 2014
    #5
    ddw1668

    ddw1668 Senior Member

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    Location:
    Murrells Inlet, SC
    How would running at low speed (guilty) affect something like shaft whine? These are inline six turboed Macks at 650hp each.
  6. Capt Ralph, Jan 31, 2014
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    Can you determine if the whine is closer to the flange or shaft log? Is this a new noise or always been there?
    ,rc
  7. Capt J, Jan 31, 2014
    #7
    Capt J

    Capt J Senior Member

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    On the boat with Detroits, the turbo's would get carboned up and the vanes in them would start scraping the carbon on the housing and the noise actually was being transmitted through the shafts. It was a weird higher pitched noise and you'd hear it best 10' aft of the engine room above where the first cutlass bearing was. 5 different people swore it was coming from the running gear. But it turned out that it wasn't.
  8. ddw1668, Jan 31, 2014
    #8
    ddw1668

    ddw1668 Senior Member

    Joined:
    Jan 18, 2007
    Messages:
    133
    Location:
    Murrells Inlet, SC
    Sounds exactly like my problem. You would swear it is coming from the shaft log, but if you put your ear close to the log it doesn't sound like the log at all.

    Think I will take her out and lose some carbon!