Suggestions for repairing pinholes in muffler?

[mike911]

Greetings from Canada, all the best for the holidays and health in 2015.

I'm preparing my muffler for re-paint, after a media blast I noticed 3 very small holes approximately 1/8" diameter.

Looking for some suggestions to repair these pinholes, epoxy, muffler cement, or brazing of some type?

Maybe you have experienced this issue or can recommend a fix?

As all ways your help is appreciated.

Regards,
Mike

[1QuickS]

I've brazed patches very successfully, welding is easy to blow thru thin metal.

Pinholes implies remainder of muffler close to suffering the same issue; replace muffler is my recommendation to avoid future irritations by pinholes.

[mike911]

Thanks Paul, I did another closer inspection and found one hole, small diameter, approximately 1/8" that appears to be right through.

The metal all around this hole looks rust free and is quite solid. When I poke at it with a sharp pick there doesn't seem to be any soft or weak area, maybe worth trying to braze it as a short term repair?

Any suggestions on what to use or technique?

Thanks again,
Mike

[1QuickS]

Not much more than to clean the parent metal by sanding and cut a patch of metal to cover the hole and sand it clean also, perhaps 1/2" in diameter, not square since the corners will easily melt during the brazing. It would be good to have the patch of equal to slightly thicker material to help keep it from melting during the brazing process. Create a method for holding the patch in place, something like a stiff wire that can be bent to apply pressure. Braze using 1/16" dia rod and heat the parent material in a circular pattern around the patch and don't try to heat the patch directly. Use a "0" tip if you have it and a slightly "soft" flame, one that has a feathery blue cone and not a sharply defined cone. The soft flame helps reduce the intensity of the heat. Once the area gets dull red it is time to heat the tip of the brazing rod until it is nearly ready to melt and touch it to the edge of the patch. If you have flux coated rod then you are good to go but if not then dip the heated rod into the can of flux and let it cover the end. Hopefully all now is ready to take the filler metal. Once you have started the brazing the remaining perimeter of the patch should fill quickly and due to the connection between patch and parent via the filler rod there is less risk of melting the steel pieces.

Obviously be careful of the flame but I assume your muffler is on your workbench with not much else in harm's way. If the muffler can be positioned so the patch is level and you can easily work then all the better; overhead and other out-of-position work makes the repair much more "interesting".

Once cool, the flux can be chipped off, most are water soluble, in any case, get the flux off and sand the repair to clean-up.

Test your technique on some donor metal first.

[mike911]

Thanks Paul for taking the time to provide clear instructions on doing this repair. I have the muffler on my bench and may solicit the help of a friend who has some experience.

My experience is very limited so I appreciate the details, based on the overall condition of the muffler and the strength of the material in the specific area of this hole I believe brazing will do the trick at least until a good replacement can be sourced.

Thanks again for your help,
Regards,
Mike

[bfunke]

Unless the pinholes are confined to a dependent area where moisture collects, more will materialize after you patch the ones you have. A long term fix may require more than brazing.

[boxster03]

time to find an Ed China trick