Sand blasting gasket surfaces?

[Roadrash53]

I used to build race engines. I've had a lot of experience with aluminum heads and block for automotive engines. First thing to remember is that a V8 head has a lot more surface area for the gasket to seal than a motorcyle engine. Blasting the gasket surfaces on a motorcycle engine is not a good idea for all the reasons mentioned above...reduces sealing area, rounds off edges, uneven blast pattern leaving valleys, stuck on particles make the surrounding blasted area uneven. Here is how I always cleaned the gasket area for any motorcyle/autmotive engine I have built. First, with a very sharp gasket scraper, clean all the surfaces....a gasket scraper is no different than a good chef's knife. The sharper it is, the easier is is to use and the better cut you get. You want it as sharp as you can get it so you don't have to use much pressure. Its the pressure that causes gouges, not the sharpness of the tool...keep it sharp and be gentle. Second, once the surface is free of all gasket particles, dirt, mud, goo, etc, then use a sanding block with nothing less than 600 grit wet/dry emory cloth. Give the surface a very quick and very light sanding. Again, no pressure, just let the emory cloth do the work. Next, if there are any gouges, scrapes, or imperfection in the gasket surface, use JB Weld or Liquid Steel to fill them. Don't use Bondo or any type of body filler. It expands at a different temperature and rate than the metal. Just mix it up and fill only the gouge. Use the gasket scraper to get all the excess removed while it is still wet. When you apply the gasket, use only a high temp silicone sealant. Don't slop it on. But, before you use silicone, read your service manual. Some gaskets are made to be installed dry or are made to work best with copper sealant. Follow the service manual or the gasket mfg's recommendations. Only use enough to cover the sealing surfaces. There you go. You should never have a oil leak and the next time you disassemble the parts, it should come apart easily and be easy to clean up again.

[mattyo]

Thanks Roadrash, that was a very good walk-through. Have you used the copper sealant before? I don't know if any of my gaskets will call for that but I'm curious about the theory behind it. Is the copper generally used for the gaskets that are metal with some compressible material sandwiched in-between?

[Roadrash53]

Yes, you are correct. Copper sealant is generally used on metal gaskets and/or metal/fiber sandwich gaskets. For paper or fiber gaskets, use silicone or Permatex(yuck!) Silicone is SOOOOO much easier to clean off during a disassembly!

[mattyo]

Originally Posted by Roadrash53

Yes, you are correct. Copper sealant is generally used on metal gaskets and/or metal/fiber sandwich gaskets. For paper or fiber gaskets, use silicone or Permatex(yuck!) Silicone is SOOOOO much easier to clean off during a disassembly!

Hahaha, then I think I'll be going with the silicone!

[luisr320]

I'm stuck at the "30 years old gasket removal". Whatever I do I keep making small scratches on the gasket surface. Is it enough to get a very light coat of silicon liquid gasket and the paper gasket itself? What about Permatex Indian Head Gasket Shellac Compound and the gasket?

[adlowe]

Since I don't have a blasting setup available, it's moot but I would NEVER sandblast a gasket surface -- if I was going for fast and shoddy I wouldn't put that much effort into it. I might clean the surface with a media blast, maybe, if I had one that was quite a bit softer than the metal -- crushed walnut shells? The biggest thing that would hold me back is ensuring that I could be certain I cleaned off/out ALL the media without leaving a trace behind. (I would definitely view difficulty in cleaning out the media as a far bigger concern than wearing away the gasket surface.)