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MG MGA - Fuel tank bung washer

What is best, a copper or fibre washer?
Gary Lock

Fiber may work. Prefer copper for longevity.
Barney Gaylord

I found that the copper did not seal properly on mine so I had so use some 'plumbers horse hair' to get a tight seal.
I always wondered if a cork/rubber material would be better.
Gonzalo Ramos

Anglo Parts show it as a fibre washer and Moss show a copper washer (6K638)as the seal, the same part# as used with the sump drain plug. Take your pick, a fibre washer will seal easier if the surface of the hole or the plug is rough, but if the mating surfaces are good the copper washer, as Barney says, will last forever or at least until you disturb it again.
Lindsay Sampford

I've had the same copper washer on mine that it came with 14 years ago, and with the old sender unit problem I've drained the tank a few times now.
To seal a copper washer has to be soft as they are when new. When you do the job you never have a spare copper washer handy. So soften it yourself.
Ensure there is no petrol on the washer after its removed from its bolt. Heat it to red heat and quench it in cold water. Hooking it on a piece of iron wire over a gas flame on the cooker / blow lamp will make it easy. Clean up the washer and refit it. This works for all those copper washers around the car too!
Pete
P N Tipping

PT purely out of academic interest I though the process you describe is for hardening. Isn't slow heating to temper/anneal the metal the way to go or is copper the reverse of steel when it comes to heat treatment?
J H Cole

What Pete describes for annealing is correct, but don't ask me why it's the opposite for steel!
Lindsay Sampford

Lindsay - steel is something else all martensitic and austenitic stuff going on. With a high enough carbon content quenching will harden it dependant on the temperature its heated to.
With the non ferrous metals we play with like brass, copper and aluminium when you heat them up they will recrystalize. You don't have to quench these but it is quicker.
When we tighten up our copper washers they 'work harden', annealing by heating to red heat will soften them again. Brass is similar in needing a red heat. To anneal aluminium first rub a bar of soap over the surface leaving a mark. Heat just until the soap mark turns black and then quench. This works fine on my ally MGF sump washer.
Pete
P N Tipping

Thanks for that Pete. The information on annealing aluminium washers is particularly useful.
Lindsay Sampford

This thread was discussed between 13/07/2011 and 20/07/2011

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