Engine rattle

Sounds like top end rattle. Off and on, no loss of power.
99 Outback L S with 1200 hrs.
Rattled a bit at idle then went away.

Don’t recall hearing this before.

Any ideas or experience in this would be helpful.

Thanks

Cold start?

Cold rattle can be vale train from lack of oil until the the pump gets it there. How is your oil pressure (assuming you have a gauge) and when was it changed last.

Carb or EFI?

Fuel injectors make noise when clogged of failing.

Loose brackets, loose bolts from vibration, pulley going bad on belt drive. Could be something dumb like this.

Does it sound like shaking a paint can? That would most likely be lifters.

Oil fresh only 3 ski runs since I put it on the water Sunday.
Holley marine avenger carb, oil level good on stick, no gauge.
I noticed the noise when idling after the ski. Turned it off. Started back up, no noise ran smooth at ski speed home.

Will take it out tomorrow and check it. I bought this boat new so I am sensitive to the sounds it makes. I had a dozen threads on the old forum, can’t find them now.
Sound is not like a paint can shaking more consistency in the rattle. Very tight to tk tk tk. I’ll rev it and see if the rattle increases with the rpm.
Thanks

Check your spark plugs, wires, and coil. Could be a ignition tick. I had a loose spark plug in a car engine and had no performance loss. It would change with idle and at 3000rpm would go away.

Exhaust leak. A gasket could have started to go. I knownthe manifolds are liquid cooled so doesn't seem likely, but check the v-band connections.

Hopefully nothing that keeps you off the water.

Pretty sure it’s the upper water pump.
Started it this morning and the rattle is coming from that area.
Changed tha more than ten years ago, not difficult with help, but looks like I’m off the water for the holiday weekend.
Do you know if there is a way to attach a video with sound?