Weld (OA or MIG) or braze muffler repair.

[Captain Dirty]

At 900 hours the muffler on my JD F510 front mower failed; the right (exit) end bulkhead was flapping in the exhaust breeze. A replacement muffler is no longer available, and I decided not to chance a used one from e-bay,

The muffler is an approx. 6” diameter cylinder; the R end was a disk with an approx. 3/8” lip around the periphery and a slightly shorter lip around the exit pipe. The lip faced outward, apparently a press fit, and the end of the cylinder was rolled over the lip. Using heat and pliers I was able to unroll the end of the cylinder and extract the disk. Having it apart I was able to clean the surfaces with a wire wheel, Dremel, and sandpaper. There are slight distortions, small (<1/16”) tears, and rust pits that did not come clean. The metal is 22-24 gauge, and I am wary of removing more metal. My intention is to tack tabs 3/8“ inside the cylinder to prevent setting the end too deeply, fit the end, use pliers to press the lip and the cylinder together, and edge weld.

The methods available to me are MIG (0.030" ER70S-6), OA, or brazing. I am concerned about blow-out, although I could probably cob an unsightly repair plug. Would brazing be a better choice as I could build a bigger fillet or is fluxing the outer side of the lip and inner side of the cylinder and what rust remains a problematic? Which method would most likely give the longest lasting repair? TIA.

 

[sandman2234]

I had a Ford 1100 muffler fail, with replacement over $500. I sold it, and the next owner wanted me to drop by the nearest salvage yard to see about getting a set of replacement tires and rims when I delivered the tractor. I saw another tractor with a muffler that looked like the 1100, and bought it for $50. It actually didn't exactly match, as the bolt pattern was just a little bigger. I machined an adapter out of a block of steel and sent it to the new owner. He was happy!
David from jax

 

[John0829]

I personally am a fan of brazing, done right it will out last the metal you put it on.

 

[yomax4]

I had a similar issue with a tractor that muff rotted out. The header pipe was still good so I cut it off and welded on a totally different muffler that worked better than OEM. I did have to fab some simple mounts to hook it all up.

 

[arto98607]

I had to replace a muffler on boom lift and found out OEM replacement would cost $800+ so decided to make my own out of heavy 6" pipe and 1/4" steel for ends and couple of inside bafflers.

It has worked out great.

No aftermarket direct fit was available due to inlet / outlet orientation.

Rusted out original:


$800+ OEM:



Homemade version installed:

 

[CliffordK]

You'll have to judge how much good material you have left. But, I'd fear that whatever caused you problems will be a headache for quite some time. Unless you can find something that you're sure is good solid steel.

Brazing may be best if you can find some good solid steel. Perhaps look for some flux that is designed to wick the brass.

Congrats to @arto98607, I've wondered about doing scratch made mufflers a bit heavier duty than stock.

 

[rScotty]

I've done a lot of braze repairs to mufflers and exhaust systems in the third world working out of an old mobile repair truck. Brazing exhausts works like a charm.

The trick is not to overheat the steel. Use lots of flux and a soft oxy/acetylene flame.
Heat the area and let the braze flow by itself to the steel. The thicker steel will naturally heat up more, and the braze will go there on its own - which is exactly what you want.
Add more braze & flux then move the molten braze around with the heat of the torch.
Works even better for patches, too.

rScotty

 

[paulsharvey]

I recently wire flux cored sons exhaust on his truck. When he and his buddies cut the muffler off, they cut so close to the muffler, you didn't have enough pipe left to get a clamp on. Used some 2.75" steel fire sprinkler pipe, about 3" long and just ran 0.030 wire. Worked fine, but was ugly. Took several grind and recap to get it completely sealed up.

 

[paulsharvey]

It would have been easier if it wasn't 2-2.75" into the muffler and a single 3" out. The welds are ugly for sure, but they work.

 

[Captain Dirty]

U P D A T E

Brazing was the more prevalent suggestion but all came with disclaimers ". . . done right it will outlast the metal you put it on"(john0829), ". . . if you can find some good, solid steel" (CliffordK), "The trick is not to overheat the steel."(rScotty) I used MIG to tack the tabs so they wouldn't come adrift inside the muffler during brazing, spread flux on the inside lip of the cylinder, the outside lip of the end wall and the mating surfaces on the end wall and exit pipe, installed the end, and tried to close any openings between the flanges with pliers. I may have over-fluxed as it sucked up over 3' of brazing rod; if I were to sell the muffler, I would brand it "Golden End".
I tried to use braze to plug a couple of pinholes in a sheet metal heat shield that partially encircled the cylinder and succeeded in blowing the holes out more. Using the increased mass of the short weld beads that had attached the heat shield to the muffler I was able to MIG-build those welds into something of a hook that held the shield and plugged the holes.
The muffler is now re-installed on the mower and has held for over 2 hours. Hopefully, a further update reporting a failure will not be forthcoming.