Muffler Internal Failure

by Dennis Urban in 912 / 914 Technical Questions 8 years ago

Does anyone have experience with a muffler failing internally? If so, what did you do to fix it? Or did you spend $1,200 for a new one? Do your mufflers have an internal pipe as I am describing below?

My muffler on my Rans S-7 Courier has an internal tube, centered in the muffler, running from side to side, approximately 2 inches in diameter. It has holes drilled in it to make it perforated. This tube exits through the outlet pipe. When gases come from the engine, they enter the outer part of my muffler and then must go through these holes into the inside of the inner tube before exiting the muffler at the exhaust outlet. It is this inner tube that broke on each side about an inch from the ends and at the outlet. The tube now rattles around in the muffler and exhaust gases can go directly out the exhaust pipe. I wonder if I could simply remove the rattling piece, and if so, what the other consequences might be. Another Rotax Owner (Kevin) suggested I might try to have it opened, fixed, and re-welded shut, which I may attempt. The way it broke on both sides and at the outlet makes me think this will not be easy.

What got me troubleshooting was the engine sounded all wrong while everything else was in the green, as explained during my troubleshooting period here:

Troubleshooting

If anyone has experience with this, I would appreciate the help.
Thanks,
Dennis

Re: Muffler Internal Failure

by Bill Hertzel » 8 years ago

Bill Hertzel

13 1.95k 7.96k

If this is a new muffler with low time on it, you should contact the Manufacturer.
There is no reason the internal baffles and tubes should be detaching.
This would be a defect in materials and/or workmanship.

If this is a muffler that has seen a lot of hangar time, it may just be rusted out and there will be no reasonable way to repair it.
A new exhaust may be in your future.

Engine hours matter little to the exhaust system.
Once you get wet exhaust gasses on the internals, the clock starts ticking.
Flying for 30 minutes a month will kill a muffler faster than flying it every day.
Exhaust Desiccator Plugs Might help but even they are pricey.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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Re: Muffler Internal Failure

by clyde lind » 8 years ago

clyde lind

0 1 0

Dennis, I recently had to replace my muffler on my S-7S at about 1050 hours and 10 years old. Same symptoms as yours, you could hear the parts vibrating around inside the muffler. I borescoped it and could see that the central tube had corroded and broken up.

I replaced it with new from Rans, I think about $1000. I cut the old one open to examine it, the can was in good shape but the internals were shot. There are shops that will rebuild a aircraft muffler but I don't think the savings is all that great.

As an A&P, I've replaced many mufflers that cracked out with less then 500 hours on them so I felt I got my money out of this one. Like Bill said, moisture is the killer, you didn't mention how many hours you had on yours.

Bill

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Muffler Internal Failure

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