Granpooba

My Feedback: (5)

Running an OS .60 with a Pitts Style muffler in a Great Planes Shoestring. It has nosed over a couple of times for me on landing and yesterday I noticed one exhaust stack cracked and the other cracked enough that when I pulled on it, it broke off.

Guess, I am getting cheap in my Senior Years, but I just did not feel like buying a new muffler, thus I thought, hmmmmmmmmmmmmmm how about trying good ole JB Weld. It seems to hold well for every other use, so why not try it on a muffler stack. Thus, I applied JB Weld to the base of the cracked stack and used JB Weld to put the other stack back in place.

Has not hardened enough to make a report on it, and will probably be flying it within a week or two, but in the meantime I am just wondering if anybody has tried or used for the same fix that I have stated above ?

1QwkSport2.5r

High heat and methanol weaken JB weld. I wouldn't expect the repair to last very long.. You might have a better shot if you rough up the metal around the broken joint to be JB Welded. Even then it's a crapshoot if it'll hold or not.

speedracerntrixie

My Feedback: (29)

I agree that the end result will be the same. The big issue is that the aluminum is now contaminated with oil. Almost impossible to get clean enough to yield a good bond. If the contamination was not there you would have a good chance of it working by doing a multiple temp heat cure to increase the JB welds TG. Start off by curing at 150 for an hour then bump up to 200 and then 300. During normal operation that part of the muffler should not see 300 degrees, if it were then the odds are the joint would fail. The key to any epoxy bond is surface prep, the surface has to be clean and you need to abrade in order to "excite " the surface.

TomCrump

Let us know how it works out.

I've had mufflers repaired at the local welding shop. The cost has never been more than $30.00.

coralcape

My Feedback: (4)

I have had good luck with lo temp aluminum rod. Clean muff in laquer thinner, abrade the joint on your wire wheel 'till it;s shiny. Use MAPP gas. Most important step is to pre-tin the joint, If you have success be prepared to fix everyone else's muff in your group (ask me how I know). Good luck. red

Granpooba

My Feedback: (5)

Before I applied the JB Weld, I did clean both the stacks and the muffler body with acetone. Seems like acetone is my favorite for cleaning and type of gas / fuel / oil residue.

I also thought about taking the muffler to a welding shop. Have not checked any prices, but as one fellow stated, he paid about $30.00 for repair. For that kind of money, I would just skip the repair and purchase a new muffler.

Did not want to put to much $$$$ into this model as I only fly it 2 or 3 times a year.

If the repair holds for a couple of years, great ! If not, then ohhhhhhhhhhhhhhh well , lessoned learned.

aspeed

I think the low temp rod would be good too. It is likely what was used originally. Having said that, see how long the JB works, silicon RTV may hold too for a while. I have built a muffler with just machining and press fits, Fine thread extensions may work too if there is enough meat to thread into.

earlwb

I have used aluminum solder to fix mufflers before. So it is a good alternative. But someone that does welding is also a good choice too.

Granpooba

My Feedback: (5)

Quick update:

Just checked the JB Weld after allowing to set up overnight. Everything seems to be real solid. Just as if the stacks were never broken or cracked. With that said, we all know that only flying the model will be the true test. That will most likely happen within the next week or so.

If you see a smiling Icon you will know it worked. If you see one with tears, well you know. LOL

flybyjohn

My Feedback: (2)

In the future, I think the alumirod or aluminum solder/braising rod is your best bet. (sold at home depot, harbor freight, and other places) I have used it a few times and just used a propane torch. Read up on the proper technique and you will be miles ahead. Use a stainless brush to brush the metal. Heat the metal and rub the rod on the metal until it melts, thats the only way I have been able to get a good bond with it, but the bond is very strong.

Granpooba

My Feedback: (5)

This is one of the problems when you have to many models. After awhile you spend more time doing maintenance and repairs than you do building.

Luckily / happily my Father who is now flying models in heaven was a welder by trade and did teach me a few welding tricks. Everything that you have mentioned, I know are the proper procedures to follow.

thepamster

I am interested in your result as well Grandpooba. I just tried this on a Bennitt muffler for my dle55ra. The stacks are just loose, no physical damage. I cleaned the surfaces real well then roughened them up good and cleaned again. I haven't run it yet but we will see. I will post my results here as well.

coralcape

My Feedback: (4)

If you want the JB to hold, you have to eliminate vibration. I think you could use a tie strap between the muff body and exit pipes. Good luck, red

aspeed

Shortening the stacks to the shortest possible length would not hurt either, as well as little stubs or pressure type nipples that thread in, and silicone extensions to eliminate the vibration. This is all kind of a lot of effort, but an improvement from stock I suppose. It did fail in the stock form and would continue to do so.

Granpooba

My Feedback: (5)

UPDATE:

Flew the Shoestring with the JB Weld repaired muffler today. Flew it a few times and did not find any fatigue, looseness, weakening, movement, etc, etc, etc.

Also to note, because some IDIOT decided to drive their vehicle across our runway when it was wet and muddy recently, it left some pretty good size ruts. Well, needless to say on the last landing of the day, my landing took me across one of the ruts and the model nosed over and rolled a short distance on its nose. I thought, well their goes my repairs, but to my surprise, no damage at all.

With all of this said, to date, my JB Weld Pitts style muffler on my OS .60 is holding just fine. Hopefully it will continue to do so ..............

thepamster

Thanks for the update pooba. I haven't flown my Pitts yet with the repaired muffler. I will post my results as well here in the next week or so.

thepamster

Well mine didnt work. After the first flight the tubes were getting loose. By the third flight they are about to fall out.
I am really disappointed with my Bennitt muffler as I have had good experience with them in the past. My G38 has a Bennitt muffler which is essentially the exact same muffler as the dle 55ra and after 20 years the tubes are still solid.

Granpooba

My Feedback: (5)

Another UPDATE:

My JB Weld repaired muffler to date is still holding . Have been flying it quite a bit and to date shows no signs of fatigue or loosening, or coming apart.

I am very pleased with the repair.

vasek

My Feedback: (4)

That's good news, I was wondering about the use of GB weld in mufflers. Thanks

blw

My Feedback: (3)

Any photos?

1QwkSport2.5r

I used JB Weld to hold an old Saito .40 muffler together I got from a friend (the outlet end broke off or the weld failed) and within 1 minute of running it on my Enya 60-4C it fell off. I sanded the parts to be joined with 120 grit dremel sanding drums and cleaned with acetone twice and let the JB cure fully (48hrs) and it didn't hold. Perhaps the exhaust temp being that much higher sealed its fate (no pun intended) but a 2-stroke running cooler (richer) than screaming lean might have a fighting chance of the JB holding. I personally wouldn't put much faith in JB Weld holding for any extended period of time but in this case, time will tell. I too would like to see photos of others' attempts of using JB on mufflers.

earlwb

Well it sort of depends on the muffler temperature at where JB weld epoxy is being used. Different engines and different mufflers will have different temperatures. So it will work for one guy and not the next. Usually if the temperatures at the joint exceed some certain temperature limit then the epoxy fails to hold. Vibration could have a effect too as different planes and engines will vibrate less or more strongly.

So I would use a file and wire brush and remove the epoxy and then clean it with a new stainless steel brush and go the aluminum solder route or even find a welder to weld it for you.

1QwkSport2.5r

The Saito .40 muffler I spoke of was too small for my .60 anyway, I tried it for the heck of it because my 60-4C never came with a muffler. No bother because it sounds fine and isn't that loud without the muffler anyway. I'm not out anything.

aspeed

I wonder if RTV silicon would be any good. It may flex a bit and take the heat too. You could forget about resoldering it again.

1QwkSport2.5r

RTV doesn't set hard enough. It would fall apart sooner than you could say "poof". If 3M's 5200 marine adhesive could handle the temperature without breaking down, your have a winner there. That stuff is so strong, it (when used on the mounting bracket between engine and transom) will hold a Yamaha 225hp 4-stroke outboard to the back of a fishing boat without bolts. That is some serious adhesion power. Don't think it can take the heat though.