Small OB buzz

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.

 

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.

 

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?

 

Reed valves don't typically make noise, good or bad.

 

They can if they are loose. But normally if they are loose or broken the engine doesn't run right.

 

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.

 

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.

 

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