1995 Ski Nautique. Engine clunking

[JlGascoigne]

Hi. I have a 1995 Ski Nautique, Body Glove. GT40 engine. 750 hours. Loud clunking noise paired with a pretty good vibration.
Had a manifold gasket replaced this winter and when I put it in the water there is a loud
clunking noise happening. Also appears to have some tiny metal shavings in the oil.
Before taking the engine out and oil pan off to look at rod bearings etc
was wondering if anyone has experienced this before. I'm assuming
there is no relationship to this and the manifold work I had done but I'm not
a mechanic so I have no idea. Attaching a link to a video of the clunking.
Any thoughts would be greatly appreciated. Thanks!
https://1drv.ms/v/c/18ed97fa35b599f9...FFcrPoU5mp4Z-c

[SilentSeven]

I hear a banging noise that repeats at differing intervals. Is that the noise you are asking about?

That doesn't sound like a rod knock. Uncle Rodney tends to be very rhythmic and is deeper sounding.

My guess is that the drive damper plate between the flywheel and the trans has failed and what you are hearing is lash. The plate normally masks this. Reasonably common failure item on older boats. Does the noise change as you put the boat in and out of gear? If yes, that would be a good positive indicator of a damper plate issue. Pretty simple fix on a direct drive - the transmission can be pulled in a few hours so you can inspect and access the plate.

https://nautiqueparts.com/search-res...damper%20plate

If you think you have wear issues in the engine, a Blackstone oil analysis is money well spent.

https://www.blackstone-labs.com/

Let us know what you find out.

EDIT: here's a vid of bad damper plate that's been removed from the boat. couldn't find one of with a bad plate in the boat. https://www.youtube.com/watch?v=eOcVUz9Hu3Q