Another annual and another muffler welded and or replaced. I have a 1996 MX7-180b and am looking for ideas on fixing this broken muffler problem.

First, GET THE PROPELLER DYNAMICALLY BALANCED!!!

O-360's all vibrate a lot-those are big pistons in there, and only four of them, so they thrash about a good bit.

I am always amazed at how few people get their prop/engines dynamically balanced. It is simple and cheap (~$200), and it will save on a LOT of vibration related issues.

This may not be the whole issue with your muffler, but I'll bet it will help.

MTV

DO NOT CRANK DOWN ON / TIGHTEN THE JOINT CLAMP!!! The weight of the muffler should be held by the hangars on the firewall and not the clamps near the engine. The tailpipe should basically just hang on the joint clamp and dowel like a ball joint...this will prevent the cracking. You should be able to grab the tailpipe and move it freely about an inch or so in all directions when it is installed correctly. Just snug the joint clamp enough to prevent rattling...only 40 - 50 inch pounds and then back off 1/4 turn! Our tailpipe ID was too tight to slide on the muffler easily so we took it to a local muffler shop and had them "swell" it about 1/8th inch...just enough to give it a little play.

If you do not install the muffler correctly, you will be replacing them at every annual. When done correctly they will last between 800 - 1000 hours.

See Maule Service Bulletin #23 and pay close attention to step #5

http://www.mauleairinc.com/Service_Lett ... tin_23.PDF

Give AWI (http://www.awi-ami.com/) a call. No, I don't have any financial interest in the company, nor do I know much about Maules in particular. I just happened to have a random conversation with someone there and he mentioned that they are now making OEM mufflers for Maules. They found that the original Maule mufflers (made in house by Maule) could be improved upon and set out to do just that.

Good luck!

Vick wrote:Give AWI (http://www.awi-ami.com/) a call. No, I don't have any financial interest in the company, nor do I know much about Maules in particular. I just happened to have a random conversation with someone there and he mentioned that they are now making OEM mufflers for Maules. They found that the original Maule mufflers (made in house by Maule) could be improved upon and set out to do just that.

Good luck!

Unless I am mistaken, all their Maule mufflers are overhauled and not original fabrication...did I miss something?

atlee dodge also has a few tricks to improve upon the maule design. they can repair, overhaul, or replace them for you.

Here's the Scoop on AWI

AWI is in the prosess of makeing a NEW system for Maule, it will be an equil lenth tuned header system. I have seen the 6 cyl vertion and am pretty impressed, the 4 cyl setup is in the works hopefully ready in the next month or two. I had the pleasure of talking with Tom (AWI Pres) on the two swstems and hope to have a set of both systems to test fit and run in the next month. I will take lots of pictures and give a Pirep when it is ready.

Hottshot,
I've heard that Maule was playing with a tuned header system. Is this the one? Put one one your airplane and bring it to the fly-in.

a64pilot wrote:Hottshot,
I've heard that Maule was playing with a tuned header system. Is this the one? Put one one your airplane and bring it to the fly-in.

Yep it is! and I don't think it will be ready by then buy maybe!! I will give Tom call and see.

Tom is who I spoke with also. If I understood it correctly, they will begin providing systems that Maule will install on the production line as well as offer aftermarket replacements for older aircraft. Because AWIs design is superior, that should reduce the failure rate that many current Maule owners experience.

i only have 200 hours or so on $1000 worth of new mufflers, but i would be very interested in an improved design. is there talk of performance improvements due to the tuned length design? will there be an stc? will we be able to keep our aux heat muff?
keep us updated, wup. and get some spy photos for us

There will be heat muffs. If they are successful when tried and tested, Maule will be fitting as original equipment and selling as replacement. However, better means stronger and that means heavier, about 6.5lbs on the 6 cyl engines, a little less on the 4 cyls.
Lowflyby suggestion is on the money, another place to watch is overtightening of the header to riser attach bolts. The cyls all expand and contract at different rates and directions and too tight will crack the brackets. Lastly, as mtv says the O360 is shaky so don't idle at the shaky rpm usually from 650-850, find a sweet smooth spot.
Jeremy

UP_M5 wrote:i only have 200 hours or so on $1000 worth of new mufflers, but i would be very interested in an improved design. is there talk of performance improvements due to the tuned length design? will there be an stc? will we be able to keep our aux heat muff?
keep us updated, wup. and get some spy photos for us

I will work on the photos,

What happened to the tuned header?