While replacing the tired old engine with a brand new one on the 30+ year old John Deere lawn tractor I needed to do something about the muffler.
My first inclination since it is a new engine was to order a new muffler as well, but the customer decided he didn't want to spend the money for a new one and have to wait a month to get it. even knowing my labor could run as much to rebuild the old one as it would cost for a new one, but what do I care. I'm fairly certain I could have located one for a lot less than he had been quoted by 4 different sources.
So here is how I rebuilt it as such.
First I had to clean enough rust away to be able to administer the repairs. then I refitted the manifold tube to the muffler by welding a disk over the hole.
since the insides were gone as well to give it some muffling ability I decided to pack it with lathe and drill swarth. This is akin to packing a muffler with steel wool to diffuse the exhaust flow but will last 100 times longer.
Then after all repairs were made I sandblasted it with the coal slag and painted it with 2 coats of an extreme temperature paint. good for up to 1800°f. The paint is temperature cured. the same paint I used when I rebuilt my wood stove 6 years ago and that stove still looks the same as it did way back then