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Thread: High pitch whine from outdrive when underway...causes?

  1. #1
    Join Date
    May 2006
    Location
    Beaufort, SC
    Posts
    173

    Default High pitch whine from outdrive when underway...causes?

    Posted for a new member who cannot post yet. This is NOT my boat...merely posting as favor:

    Yesterday I seatrialed a '97 25 CC , 7.4 jackshaft model. Underway at throttle range 2500-3500 rpm there is a definite high pitched "whine" that is audible above the engine noise and is audible anywhere you stand at the helm or in the cockpit, especially noticable at the transom area. (remember the old days when a tv station would go off the air for the night and put up a test pattern with that "weeeeee" noise?) With my fingers in my ears I can hear the muted hum of the 7.4 and also the "whine" over top of the motor noise. The salesman assures me that this is a common jackshaft i/o noise but I can hardly believe it. I might get used to it but right now it makes me want to grit my teeth. There is virtually no vibration in the floor that I notice. The boat was recently serviced with new trim cylinders, bellows kit, shaft balanced and painted, prop repaired (not sure why the repair ticket says that instead of "recond") etc. Don't know if possible it's the prop "singing" at a certain rpm or what. Last year I seatrialed a 27 Albe with twin gassers/jackshafts and I didn't pick up on any noticable or offensive noise in the drive system.....any help or insight you or others can provide would be greatly appreciated. I love the boat but if all jackshaft CC's have a noticable whine like this one, I'm going to have to pass on owning one! Oh yeah, on start up and at idle (not in gear) the jackshaft makes a light clunking intermitently, not unlike if you would hand turn the driveshaft in your pickup back and forth to take up the slack. I assume this is ok? as there is no real load against the spinning shaft until you engage the drive or throttle up (the sound dissapears as soon as you increase rpm's or engage the outdrive)
    Many thanks,
    Alan
    1997 Carolina Classic 25
    2008 Maycraft 18
    Mckee Craft 14
    www.restlessfishing.com

  2. #2
    Join Date
    Jul 2007
    Location
    Massachusetts
    Posts
    727

    Default

    Was it a Mercury Bravo III drive by any chance? I had one on my 25 and it sounded exactly as you describe -- and supposedly had nothing wrong with it.

  3. #3
    Join Date
    Jun 2009
    Location
    Maryland
    Posts
    16

    Question Bravo III

    Thanks for the original post Bill, I'm able to post now. Bluefin 32, the boat was in the water and I couldn't see the outdrive under the swim platform....just assumed it was a Volvo as that is how the engine is listed....looking at the outdrive in a picture, from what I can see of it, it's black in color but I don't know much about them....maybe you can tell if you can see enough detail?
    Thanks
    Attached Images Attached Images

  4. #4
    Join Date
    Feb 2006
    Location
    Merritt Island, FL
    Posts
    418

    Default

    I'm am on my 2nd Bravo 3 and no way have ever heard anything like you describe.
    johnd

  5. #5
    Join Date
    Jun 2009
    Location
    Maryland
    Posts
    16

    Default

    Thanks John, I appreciate your response. My son and I both looked at each other on throttle up and said "what is that?" so I know it wasn't just my imagination, although having never been on this particuliar boat and unfamiliar with outdrives (all of my boats have been outboards) I wasn't sure if it was something wrong or what.....got louder and more steady in tone with more rpm's....weird

  6. #6
    Join Date
    Jun 2006
    Location
    Advance, NC
    Posts
    104

    Default

    Check the oil level in the reservoir to make sure the top end is being lubricated. There are also two bearings at the driveshaft transition and a bearing on the drive shaft at the top of the outdrive.

    I have had to change the two bearings at the driveshaft transition even though I put nwe ones in a year ago. If a bearing fails you might get a squealing sound from the balls either not rolling or the bearing spinning on the shaft.
    Advance, NC

  7. #7
    Join Date
    Nov 2005
    Location
    UK / Portugal
    Posts
    208

    Default

    I sometimes hear an irritating whine when Mrs Spike is onboard.............
    Tigerlily - CC 28
    Algarve, Portugal

  8. #8
    Join Date
    Apr 2008
    Location
    Gaston, SC
    Posts
    799

    Default

    I have the Volvo drive, and no whine in mine.

  9. #9
    Join Date
    Feb 2006
    Location
    Merritt Island, FL
    Posts
    418

    Default

    sometimes hear an irritating whine when Mrs Spike is onboard

    now that's some funny shiet! I often hear that whine when Mrs. Ladyd is on-board.

  10. #10
    Join Date
    Apr 2009
    Location
    Beverly MA
    Posts
    433

    Default Merc Whine

    Due to the way the gears are cut (or at least that's my story), many of the Bravo III's whine a bit. I've had several that do exactly that. Your experience will vary depending on the indvidual drive. Then add the jack shaft. It works like a sound board for whatever noise the gear train is kicking up. Of the problems that the Bravo III has, the whine generally not a problem.

    Also, if the engine is not running Perfrectly smooth, you will get some lash and associated klunking out of gears at an idle.

    Bruce Clarkson

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