This is actually sortof a Subaru question, but on my SAAB's for years I've been reusing the copper washer when I do oil changes. I think that SAAB recommends a new one every time right?
On the Subaru it's a crushable washer that starts at 0.080-0.083 and ends up 0.058-0.061. Can anyone tell me of other options used for this function and if they've moved the copper idea from SAAB elsewhere?
Thanks,
-meld
I'm not sure what the question is, but you can buy the Saab washers for about .74 cents each from the dealer. But, they never look worn and it does seem like a waste to toss it.
I have some Nissans that use a crush washer and I changed them for years without changing the washers. I kept looking at the plug thinking "I should look into getting a new flat washer for that". It wasn't until I bought them at the dealer that I realized they were the crush variety. They never leaked even when reused many times.
The copper washers can be reused if they are heated in a gas flame until red hot and then quickly cooled in cold water. This process makes the copper soft again. Reuse of the coppper washer as is not recommended as the hard copper washer will not seal as well as a soft copper washer.
SO you're saying that the copper gets hardened through the heating and cooling cycles of the engine running? I've always wondered about these things... I thought we changed them due to scratching during tightening. But, I was just guessing.
Just in case this doesn't get said... Vibration and generalised "working" (ie, mechanical flexing) of the copper will harden it. Some of this will come from temperature cycling; but don't forget how much vibration happens during everyday operation.
Work-hardening, I was once told, is why chains used for carrying loads should be annealed (put through a softening heat treatment) at intervals, to stop them getting too brittle.
-- Andrew Stephenson
Interesting. I knew you could harden copper this way but I never thought of general vibration as being enough to do the job. Makes sense through.
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