Hi
This is slightly off topic but I`m looking for a suitable material to make a exhaust gasket for a two stroke chainsaw. Its a easy shape to make basically its rectangular with a rectangular cutout and two holes for the mounting bolts - just wondering what material would be suitable?
Thanks for reading.
Paul
Car exhaust tyre depots usually have sheets of asbestos gasket material for such a job .. buy a piece off them ..
or as temp ..may even be permanent
i know that silicon high modulouse sealant does a good job ...and stands heat of up to 3 or 4 hundred C or more....make sure you buy the pure silicon ...no mastic mixed in with it ......about a pound a tube........stay away from anything made by Dow corning.........should be Dow coning...all theirs, seem to be 50/50 mastic and silicon .
all the best.markj
On or around Sun, 01 Mar 2009 16:57:28 GMT, Paul M enlightened us thusly:
copper sheet, then anneal it before fitting.
Yup, I'd agree with that. The exhaust gaskets (and head gaskets) on my 2-stroke motorbike are made of copper.
Peter
If the mating surfaces are in good order I'd just be tempted to use a smear of exhaust assembly paste - not the nicest solution but a 30 second job. It's pretty good stuff, I've used it to stop exhaust leaks from pitted cylinder exhaust mating surfaces on engines like the Lycoming TSIO-540 etc in the past. Silicone sealant turns to dust with the heat in these situations.
Julian.
Hi Folks
Thanks for the suggestions - we may have some thin copper sheet at work and I will have a look in the material rack when I`m on shift. What is the procedure to anneal it?
Cheers
Paul
To anneal: For copper, just heat to a dull red then quench or let it cool naturally (for steel don't quench)
AWEM
On or around Sun, 01 Mar 2009 21:18:19 +0000, Peter Neill enlightened us thusly:
it's very traditional. however, it's also out of fashion, I daresay the composite type ones are cheaper and easier to fit.
remember to anneal it before fitting (and before refitting if it's been run) as otherwise it won't work. You also want fairly thick sheet, something at least 1mm.
One useful source of copper and suitable for an exhaust gasket is from domestic copper pipe. Old imperial pipe 1 inch dia is useful as when it's opened out it's about 3 inches wide, and the material is quite thick about
1/16 inch or there abouts, but 28mm should be OK although it will be thinner. For a 3" x 3" x 1/16'ish sheet of copper cut off 3" of pipe; then cut it parallel to it's axis. Don't attempt to open it up yet. Put the bit of pipe over a gas flame, I use the gas hob, and leave it till it's dull red then remove it and drop it into cold water. After it's cool enough to handle it should be soft enough to open up with with GLOVED fingers, but watch out for the burrs, use a pair of gardening gloves or better. Now cut out the gasket soften the copper again and fit it. This works for me for exhaust gaskets.I hope this helps.
Mike
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