Tip #6: Re-Using Copper Washers
Its not that I'm cheap… Ok, let me re-phrase that. Its not JUST that I'm cheap, it's that I'm lazy and don't plan well.
Copper crush washers really shouldn't be re-used. To seal effectively the copper must be soft, as it is in an annealed state. The very act of crushing it under a bolt work hardens the metal, and years of being bolted to, say, your turbo, can have a tendency to age harden it as well. There is a decent chance a used, crushed, aged copper washer might seal again, but the only way to be sure is to try. In my experience, copper crush washers are not used anywhere you can afford to be wrong.
Common sense says buy new crush washers before assembling anything important. Reality says I didn't remember to and now its 10:30 on a Sunday night and I'm not stopping now just to wait for the copper washer store to open.
So, if you can't plan either, here's how you refurbish a copper washer.
First, get your propane torch out and heat them unti they are glowing like toilet seats in hell. If you're using Propane, you'll probably have to fashion a little oven from scrap brackets and aluminum tape, like the one pictured above, to contain the heat of the torch. Otherwise you won't be able to get them hot enough to really glow this well. Don't worry, you can't melt copper with propane. (You can melt copper with MAPP gas, though, so be careful!)
Now, let the washers air cool slowly. Once you can touch them, you need to get rid of the ridges left from the last time you crushed them. Get some fine sand paper (at least 300 grit) and something flat. If your garage is too messy to find a flat horizontal surface, tape the paper to a window (of your house, not your car!) Glass that's less than 70 years old is usually very flat.
Now gently press down with your finger and sand simultaneously sand the washer and exfoliate your fingertip.
The washers will have turned black with oxidation as they cooled. You'll know you're done sanding when the whole face of the washer is shiny copper again.
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