Small OB buzz

Discussion in 'Outboards' started by Easy Rider, Nov 19, 2016.

  1. Easy Rider
    Joined: Oct 2009
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    Location: NW Washington State USA

    Easy Rider Senior Member

    I have a 4hp Johnson "Light Twin" outboard. They started in the early fifties as a 3hp. Most were 3 1/2 hp from the 60's and I belive mine is one of the last at 4hp.

    I bought it recently and got it running very well. It has a rather loud buzz that sounds like sheet metal vibrating. It's loud enough that I'd like it gone. I think it's probably buzzing reed valves and have no idea if new reeds would fix the buzz. Or perhaps it is sheet metal. Before I try to find loose sheet metal do reed valves chronically tend to do this? It starts at just about exactly half throttle. Don't need much more power but hate the buzz.
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    The old technique of a length of wooden dowel (rounded at both ends preferably), with one end pressed to your ear opening, and the other to the engine, and moved around till you get the loudest report of the sound that is troubling you, might help. That can assist in isolating the source.
     
  3. Ike
    Joined: Apr 2006
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    Ike Senior Member

    Those old Johnsons were just plain loud. My father had a 5 HP made in the 50's and it made a hell of a racket. I had a 1980 2HP Johnson and it was really loud too. I don't know what the buzz is though. Could be a loose reed valve. have you checked them?
     
  4. ondarvr
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    ondarvr Senior Member

    Reed valves don't typically make noise, good or bad.
     
  5. Ike
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    Ike Senior Member

    They can if they are loose. But normally if they are loose or broken the engine doesn't run right.
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The only time I've heard a reed valve buzz, was just before it spit them out. I'll bet on the loose sheet metal and the dowel in the ear trick, works very well.
     
  7. Easy Rider
    Joined: Oct 2009
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    Location: NW Washington State USA

    Easy Rider Senior Member

    Thanks all for the input.

    Ike how do you check reed valves? Seems to me you'd need to take them out.

    Re the noise of these old OMC's I've found the newer ones w the FG covers (as in hoods or lids) are very acceptably quiet. Wouldn't have one w the metal covers.

    OK I'll get my stick of wood .. and perhaps a tube to listen through.

    Thanks again.
     

  8. Ike
    Joined: Apr 2006
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    Location: Washington

    Ike Senior Member

    Depends on the motor, but it's just a visual check. They are pretty simple.
     
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