Scratched aluminum block

Small ball peen hammer.

Can you elaborate on the technique you're suggesting? Just some light tapping all around the groove?

He's messing with you.

Rol-loc scotchbrite disk in a rotary file. Try at your own risk! This stuff polishes aluminum quite well but can remove alot of material. Dont use the coarse ones, they plow right through aluminum. HTH, Ben

going a material removal route it might be best to start with a simply polishing compound or a very fine (1500 or 600 grit) sandpaper.

Not necessarily. You can take a light machinists peen, and reduce the uplift of the scratch, working carefully.

People have used flat bastard files to take away minor imperfections too.

You would like the surface to be nearly mirror smooth but in the real world this doesnt always happen.

yup

I'd be tempted to simply try to dress it down with a stone like you use to sharpen your pocketknife. CAREFULLY. don't remove any more material than you have to.

nate

only half joking. I've got a little metal hammer from a fire extinguisher box that I'd be tempted to try. I really don't like the idea of filing or otherwise abrading on the heads.

I'd be real tempted to try using a machinist's scraper, a plane iron, or even just a decent quality knife that has a straight edge. Set it down at one end of the scratch, angled slightly across it (like they angle the blade of a road grader), tilt the top slightly in the direction you're going to move it, then draw it down the length of the scratch with enough steady pressure to "catch" the ridge. Repeat as needed to get the ridges gone without digging into the deck.

Right. Check for high spots with a machinists straight edge and a light behind it. Tap down the high spots so that they won't hold the mating surfaces apart and make a worse seal.

The scratch itself isn't that big a deal as long as it doesn't create a connection between two systems that aren't supposed to be connected.

I'm with Don on this. I'd use a gasket scraper with a fresh razor in it, and I'd very carefully "shave" any curl of aluminum from the scratch that might stick above the deck. I wouldn't polish with any power tool, and I sure wouldn't use sandpaper. *Maybe* a light touch with scotch-brite wrapped around my index finger. But really, I'd just use the scraper to remove any lip of metal that might have gotten pushed up, then hope it seals. You can't put metal back in the scratch, and removing any metal around the scratch just lowers the compression on the gasket in that area when everything's assembled.

I think you've got the general idea, Steve, but the way you say it, I think you've got what I meant backwards - The action needs to be more like using a putty knife to "mash material into the gap" than "trying to get under a gasket".

Trying to "get under" the ridge is pretty much guaranteed to make things worse than they are now. You want to scrape the top of the ridge off until it's flush with the main deck, not "cut it out".

Your second paragraph describes what I meant. "Shave" any up-turned metal so that its flush with the remaining good surface, NOT "dig" under anything. A gasket scraper held very nearly parallel with the block deck will do that, just like you want to "shave" stuck gasket material off, not "dig" under it.

I appreciate all the thoughtful replies! I think I have the general idea now. I just need to get myself a decent straight edge so I can do more than guess at what is actually going on at the edge of the gouge.