Hi!

We're looking for a exhaust system for our Mx-7-180 O-360 C1F engine that lasts for more than one year.

We've wealded our exhaust system at least twice a year for the last 7-8 years, and I'm now wondering if there is a system to buy which will keep the cracks away.

I know there's a lot of threads here on the forum, but it's a bit hard to sort them out in the search function.

Any recomendations?

Powerflow was offering to produce a tuned system,but they didn't get enough pre-production orders. (See modifications section)

The secret to longevity with Maule exhaust ALL joins MUST be taken apart and cleaned to a lose slip fit,nothing too tight on the reinstall, tale pipes weight fully supported by reinforced rubber straps from firewall and several inches of movement at pipe tip in all directions!!!!
Even the cylinder outlet nipples need some slack between them and muffler header pipes.

I learned this after several re weldings & rigid reassembles.

Lose & Jiggly keeps it from shaking-vibrating itself apart (cracks )

Loose and jiggly. you are talking about the exhaust system.

Yes regarding the exhaust.
Many if not most outher "things" are best taught, firm and tight.
Loose & jiggly is the best I can described the exhaust installation.

Basically the 180HP engine is the shakiest engine out there and is worst then the 235 by far.... Having gone thru an exhaust system and replaced with another design on a field approval, I will say that leaving tubes loose, tp loose, snugging up, or whatever you do, they still crack. I finally got a new system with approx. 1000 TT on aircraft, and probably 50 weld repairs. The new system, not so much as a crack after 500hrs, but is designed considerably different with slip joints allowing for expansion, and rear ball joints at TP joints. The old system maule uses is just that!!! It basically dates back to Stinson days with franklin (very smooth) engines which are totally different animals. Unfortunately maule, inc, who know of these chronic exhaust problems, don't see fit to do anything about it!!! This is unfortunate as it has the potential for starting a fire, and I'm sure resulting law suite could and would be more expensive then a good redesigned system... These Maule airplanes have way more potential then the factory seems willing to work on extracting. And in todays environment, it's much easier for factory to modify, add to TCDS, or an STC... They actually did do some exhaust prototyping, but new system was too heavy. If they'd like a lighter, proven system, I know where and who would build all they want for a reasonable price if anyone at Maule interested. Otherwise, I guess most will just have to live with what they got as there are not enough 180HP versions out there to make an STC worth the investment as some of you found out trying to get powerflow system certified.

Thanks for answer.
Yes we've been welding our exhaust system on every service the last 7-8 years.

So it's time for us to find something new now, I think.

Atlee Dodge of Alaska makes an exhaust system you could check into.

maules.com wrote:Atlee Dodge of Alaska makes an exhaust system you could check into.

Not for the 180HP they don't, but they can and will rebuild mufflers and will also do the ball joint mod on Tail Pipe and Header. Doesn't totally eliminate problem, but does help considerably... And I suspect if you sent the exhaust stubs out of cylinders, they would eliminate that sloppy slip joint, weld a solid SS tube with flange welded on to it like they do on the 235HP systems, which in itself eliminates about 8 places that crack?

FAA approval issues aside and all of those nightmares, and remembering that I have very little mechanical experience (so don't beat me up), why can one not create a flexible exhaust system using something like MD3 High Temperature Duct Hose which is 316Ti titanium stabilized stainless steel? I realize that it is not smooth inside but surely a larger diameter could offset the resistance created by the interior corrugations.

It seems like all the problems with Maule exhausts come from vibration induced stress cracking of the thin metal tubing used to make the exhausts. Which begs the next question; why not use a stronger metal? Surely an extra 10-15 pounds in the exhaust system would not devastate the W&B.

Greg

Maule-Norway, if you can accept a little down time, you could send your mufflers and headers to Atlee Dodge of Alaska, Knisley of California www.knisleywelding.com, or Dawley of Wisconsin sales@dawley.net
All these companies will rebuild your mufflers using one small part and produce a better product than the original at approximately the same price as a new unit from Maule.
It is important to note the O360 Lyc is a rough engine at low rpm so keep the idle at around 900 or wherever the motor smooths out.
Do not over tighten the header bolts to allow interference movement at the attach lugs.
Make sure the tailpipe hanger straps are taking the tailpipe weight.
Set the U-bolt double nuts loose enough to allow the tailpipe to move 2 inch in all directions when hanger is not attached.
Use throttle thoughtfully to avoid backfire.
Check that flame trap baffles are intact at each 100 hours.

Anybody out there have the bucks to fund Powerflow and share the STC with them? I unfortunately don't and for whatever reasons, Maule doesn't see that as a good investment

What Powerflow had seemed like such a great option , more horsepower and more longevity that I was happy to commit to buying a unit; I replaced a muffler last annual (somewhat cheaper than a weld) for much less but it is the 2nd time since 2006 that I have owned the plane since new.

Some types have sugar-daddies; it certainly would be nice if Maule had one.

$4,000 for the Powerflow exhaust just to pick up 4-5 mph just didn't seem worth it.

(Thought I'd resurrect this thread rather than post one with essentially the same title)

Yesterday afternoon while turning base to final the engine started sounding a bit different. Landed full stop safely. Noticed the engine bogged badly when the throttle was opened up, and the fuel mix was acting oddly when I went to lean it for taxi. Removed the cowling today to find this:





Yikes. Less than an hour after the last annual, the first one I haven't assisted with due to a work conflict. Usually I'm able to put the tubes back on myself and I religiously follow Jeremy's description of having the 2" of play etc. This time, they seemed ok after the annual (checked with cowling in place) but maybe they were just that little bit tighter. Or, the exhaust was just ready to break and picked this time to do it. At any rate, we're now faced with a decision. Do we get the current stock Maule system repaired, try to buy a stock new exhaust from Maule (though another thread mentioned an unacceptable lead time), or go with a specialty exhaust repair/rebuild shop? Airplane downtime, lifespan of new / repaired exhaust, and cost are all factors here.

What would you all recommend? The airplane is at KSPB in Oregon.

Thanks in advance,

-Heather

Ok, well, that is a result of poor inspections, AD not complied with, and wrong parts.
You are lucky to get away so lightly.
There is an AD to check for wear or elongation of the locator pin hole and non wearing of the pin.
Your pictures show an incorrect tailpipe clamp being used.
The clamp on the end of the tailpipe would not allow tailpipe movement if it was tight enough to hold the tailpipe on. A Locator pin is required and is part of the U clamp.
I would have strong words with your mechanic unless of course I am not interpreting the pictures correctly.
I wonder what is on the other side muffler.
And what else has not been attended to on the plane.

Jeremy, thank you for the reply. Yes, I did think we got off lightly as well, that could have been bad.

The clamps do have a pin, not easy to see in the original pictures:


I'll be back at the hangar next week and will take the left exhaust pipe off to check it as well. Will post findings to this thread.