1998 Chevy Lumina Engine Scratching/Rattling

Hello,

it is nothing sirious, I hope, but when I give some speed the engine sounds like it is scratching or better rattling. I thought first maybe a loose exhaust clamp, but it isnt.

Does anyone have any idea what this can be and how I can fix it. It is annoying.

Thank you

1998 Lumina 170.000 miles

When trying to find strange noises I always remove the serp belt and listen to it run without first, to rule out anything belt driven.

Good idea but it is not coming from a belt but more from the exhaust manifold.