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Honda bf30 sudden noise

C

Cdn_traveller

New member
So I had the boat out a week or two ago. It was a 7 day trip and on the end of day 4 I hear this weird knock sound on the way back to the dock. I parked it when I got back and actually rented a boat for a couple days to finish the trip.

What do you think this is? It didn’t seem to lose any power just the new sound that didn’t sound good.

 
Hi,
While I have no idea what's causing that, the first place I would look is the spark plugs. Something as simple as a loose plug could make noise like that. I have seen it on car engines before.

Even an exhaust leak can sound like an engine knock sometimes.

I would also pull all the spark plugs and look for any sign of contact inside the cylinder. A small inspection camera is a big help looking in there too.

I don't think it would run as well as you say it does with timing that's way off but it still would be something worth checking if you can't find another cause.

Sorry , no silver bullet here, just a couple of ideas.

Good luck.
 
Always checked oil level before start up ?----Checked gear oil ?-----Post results of a compression test.----Check valve clearance.
 
Last night we pulled the lower off it and started it for a few seconds. Without the lower connected, things sound fine.

Is there a bushing or something at the top of the drive shaft that can wear and cause the shaft to knock against the housing?(I think I read that somewhere)

Could the noise be coming from the lower unit and I am just hearing it up through the water in the barrel?(doesnt sound that way..:noise was higher up than that I think. Which led me to that bushing question.

Thoughts?
 
Get a mechanic’s stethoscope, it’s helpful for finding noises on any running engine. It should tell you if the noise is at the top of the lower unit shaft or not.
 
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