Unknown noise - 2005 Honda BF225

[bclifft23]

Bought a bass boat a few months ago and my Honda outboard motor has started making this flapping-type noise. Noise is quiet while idling and obviously gets louder as you take off. Any idea what would be causing this? I have tried attaching a video to show what the exact noise is.

 

[jgmo]

Hi,
I'm sure that Is a sickening thing for you to hear. I know it makes me cringe.
I don't have any good guesses for you.
Does it only do it in gear driving forward? Or do you hear it in neutral when you rev it up?
And what about reverse?
I'm usually not a big fan of using muffs to run an outboard but I think, in this case, running it on muffs to try and narrow down where the noise is coming from might be the preferred method to troubleshoot this.
If you do use muffs you should probably remove the prop for safety if you are going to test it in gear.

Good luck.

 

[wildebeest]

Does it make the sound if you rev it up out of gear? Sounds a bit like a loose timing belt flapping against the plastic. The first and easiest thing I'd do is check the timing belt. Just feel how loose it is with your hand. It would be noticeably loose if it was causing this sound.

I wouldn't run it until checking this. You don't want to skip a tooth and getting timing off on this interference engine.

 

[NSDON]

Check it while idling with a stethoscope, great for finding noise sources.