scratches on exhaust manifold connecting flange

[Belgian951]

Hi everyone! Another repair, another issue found! It almost becomes tradition. But it has its charms...

I'm currently replacing my leaky exhaust manifold (although I now suspect it was bad gaskets) and I noticed after cleaning the block side of the manifold, there are some disturbing scratches on the faces. There's even one port that has - what it seems like to me - a piece of metal that sticks out. Fingernail does catch on these scratches and the little metal piece. Scotch brite pads do not seem to remove it, even after a good scrubbing session that removed all other dirt from the faces.

What should I do? I'm thinking, fine grit (800?) sandpaper to the piece that sticks out, and leave the scratches for when I have the engine out and do a full restore.

Here are some pics.

Vertical scratching

WhatsApp Image 2023-12-27 at 22.34.58.jpeg (235.57 KiB) Viewed 568 times

Scratching and a metal sliver that seems to stick out

WhatsApp Image 2023-12-27 at 22.34.59.jpeg (154.64 KiB) Viewed 568 times

[Tom]

On the one that stands proud (sticks out), try shaving off the high spot with a razor blade. You can use a file, but you need to be careful not to needlessly scratch the mating surface. You can also use an oil stone to keep it all flat, but I think you risk more harm than good doing that in situ and creating metal debris that might end up in the turbo. On the scratches, I wouldn't be too worried about them -- the gaskets should seal minor surface imperfections like that. If you run it a while and start to see any black soot build up, then you could add a little smear of very high temp exhaust sealant, but I really doubt you'll need it based on those pictures. How to the ceramic liners look inside?

[Belgian951]

On the one that stands proud (sticks out), try shaving off the high spot with a razor blade. You can use a file, but you need to be careful not to needlessly scratch the mating surface. You can also use an oil stone to keep it all flat, but I think you risk more harm than good doing that in situ and creating metal debris that might end up in the turbo. On the scratches, I wouldn't be too worried about them -- the gaskets should seal minor surface imperfections like that. If you run it a while and start to see any black soot build up, then you could add a little smear of very high temp exhaust sealant, but I really doubt you'll need it based on those pictures. How to the ceramic liners look inside?

Thanks Tom, I'll try to remove the high spot with a razor blade. The ceramic liners look OK from what I've seen, but I haven't looked deep inside. I'll try to inspect it with a mirror on a stick. Don't know when I'll have the time again to continue though.