Took the boat out to the SCJB get together this past weekend and had a great time. But there is a noise. It is VERY intermittent.  It happend about 5 times throught thr day. It happened at different RPMs while cruising. When I heard it I just let off immediately and it went away. It sounds like the engine is pinging kike when it is running out of gas but there was no loss of power when I heard it. Kind of like I was trying to start the engine while it is already running. Not a clunking sound. More of a rattle. Any ideas?

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I was having the same thing going on.  It's does sound like a little binging going on.  Check timing and if good you might be having a cam going flat.  Mine was doing it here and there.  Then got worst anything over 3000rpms.  I did a compression check and found #8 was very low.  I pulled intake and found my cam was flat.  Hope this helps on trouble shooting good luck.


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I have no loss of power. It does not get worse at higher RPMs. It just comes abd gies when I let off. I went from slow cruise to pedal mashed with no issues. Went from Avi to big bend and heard it twice. Then from big bend to Laughlin strip and heard it once.  And same on our way back.  I think if it was the engine it would have blown up by the end of the day. It gets on plane very well with no noises. I dont hear it on acceleration.  Just sometimes while cruising. Gonna get new U joints and hopefully take it out once more before it gets too cold.

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This summer I had it all apart. Bearings felt good.  Impeller looked great.  No nicks or cracks. Shaft turned smooth with no noises. First trip out it made no noises. That was 3 weeks ago.

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What can make a noise intermittently?  I would think the engine would be more consistent and would have blown. Sounds like maybe flex plate cracking. But would that just "let go" if it cracked? And would it be more consistent? 

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Keep an eye on your oil pressure.
I'm guessing it's the bottom end.


-beerjet-

Beer can under or near the drive shaft or flex plate😳


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Beer can under or near the drive shaft or flex plate😳


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If I find it, I hope its full!

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Gonna check the easy stuff first. Thanks for your thoughts. Keep em coming

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Gonna check the easy stuff first. Thanks for your thoughts. Keep em coming

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I I agree process of elimination.


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454 jacuzzi wj

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I'd be inclined to think that your driveline wouldn't cause a rattle under any bit of load. Thrust bearing get greased often?

If your drive line to shaft spline is a bit loose it will rattle at idle. Once hooked, cruising...ect it will stop. Could be harmonics. Have you looked at your grate...could be cracked or loose.