Looking for recommendation for a Muffler replacement MX7-180 (Lyc O360)

[Christine]

The right side muffler for my 1988 MX7-180 needs either some welding repair (crack in the muffler) or replacement
Anyone who has a different muffler than the stock Maule muffler, please share your experience and whether you recommend it.
I couldn’t reach anyone other than Maule. Have there been any improvements in the original Maule muffler during the last few years?
Happy flying,
Christine

[Kirk]

Christine,

I have had great results with Dawley Aviation over the years. Really they have been the gold standard in the eastern US for as long as I remember. Most recently 4 years ago they rebuilt my exhaust and mufflers. Basically, it came back as a new system with improved welding on the mufflers.

Dawley was purchased by AWI of Minneapolis: https://awi-ami.com/

I have no experience with them under the new ownership, but it sounds like most of the same people doing the work. Might be worth a call to them.

Kirk

[Maule988ms]

I had atlee dodge build mine. They did away with the little slip joints at the cylinders and added their ball joints on the tailpipes. Supposed to relieve stress and let them last longer. Looking though my logs this is the 3rd set of exhaust. Hopefully these lasts longer. Very happy with them so far.

[andy]

Christine, Dawley rebuilt both sides of my exhaust system a couple of times and did a great job. The only alternative that I'm aware of for the Maule muffler is Atlee Dodge.

[DavZeeMXT]

If you can get by with welding the cracks I’d do that but it just puts replacement or rebuild off for a while. New muffler from Maule is expensive. I’ve sent them out for a “rebuild “ , which is pretty much a new muffler, costing about the same but lasts longer.

[Christine]

Thanks everyone.
Attlee Dodge handles only mufflers for 6 cylinder Maules I think.
I will call Dawley/Awi as well as Acorn welding.
If the flame tube is still intact I’ll consider having it welded, if not, putting a new flame tube into the muffler was a tedious job.
Happy flying,
Christine

[Hogy59]

AWI in Eagan, MN “rebuilt” mine.. at the time they were reasonable and have lasted longer that any others I’ve had….

[Flyhound]

Tim's aircraft in Olalla has been working on a crossover exhaust + muffler for the 180 Hp Maules. You might want to prod him on getting that project finished. My entreaties haven't been enough. A crossover exhaust would preclude two exhaust pulses travelling down the same exhaust pipe just micro seconds apart. Since the O-360 firing order is 1324, pulses from cylinders 1 & 3 combine in the same exhaust pipe, causing unnecessary back pressure. That robs some of the engine's power. Then the process is repeated in the other exhaust pipe for cylinders 2 & 4. Modified joints would also relieve some of the mechanical stresses on the system and mitigate the weld cracking problem. Power Flow offered to build a crossover exhaust for the Maules if they could get enough pre-orders. They even showed up at one of the Maule fly-ins in Moultrie, GA, but not enough wallets opened for them. The exhaust system is one of the Maule weak points.

[Maule988ms]

For the record, my engine is an 0-360. Atlee did well. Crossover is exciting to hear about though

[andy]

I tried to find the forum post where Tim's Aircraft described the 6 cylinder version of the exhaust that they created. As I remember, it had ball joints instead of welds where pipes met with spring loaded brackets securing the pipes to the ball joints. I don't remember what they did for the slip joints to the cylinder exhaust headers though. That's a weak point on my MX-7-180. The pipes deform over time due to the additional vibration and movement of the 4-cylinder engine and I get exhaust blow-by on the bottom of some of the cylinders. They can be re-formed with the right tool to fit the headers properly but it's a pain to do. Power Flow never came out with a version for the O-360. I got a good look at the one they showed for the O/IO-540 at one of the Maule Homecomings. Too many curved pieces of pipe and lots of welds in my opinion. It was a lot of money with questionable benefits. Most Maule owners decided to wait and see if the benefits were actually realized by others before investing $5000. That won't happen now since Power Flow decided not to sell any for Maules.

[Christine]

Good morning,
Last I talked to Tim about muffler, his 4 cylinder design wasn’t ready yet.and he has always so much work to do, not sure when he will be able to find time to work on the design. I would really like to wait for that one.
Awi wanted me to send the muffler in first before giving me a quote and said it would be the same or more as Maules new price.
Atlee says I should send them pictures. I just pulled it off and it looks so good except for the one crack of course that I might just have it welded and wait for Tim’s or any other improved design.
Christine