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loose pitts style muffler on dle55

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Old 02-21-2012, 11:50 AM
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SWORDSN
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Default loose pitts style muffler on dle55

I can't keep the muffler tight on my DLE55 engine. I have tried blue thread lock, red thread lock, with and without mfg gasket, with and without high heat silicone all with the same results and I have replaced the threads with helix-coils. Does anyone have a fix?
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Old 02-21-2012, 11:52 AM
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Default RE: loose pitts style muffler on dle55

buy some nori lock washers from places like Amazon and never look back
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Old 02-21-2012, 11:54 AM
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Default RE: loose pitts style muffler on dle55

Well, since we use heat to loosen thread lock, unless you got it specifically made for high temp then it won't do anything but liquify and lubricate the screw.

Clean all the threads thouroughly, replace the bolts as you probably lost their spring by over tightening them, and install them dry.

Warm up the engine, and snug the screws.

Use the manufacturer gasket.

You might but a small dab of RTV on the screw but IMO you really don't need it.
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Old 02-21-2012, 11:55 AM
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Default RE: loose pitts style muffler on dle55


Quote:
ORIGINAL: krayzc-RCU

buy some nori lock washers from places like Amazon and never look back
I think you mean nord-lock

http://www.mcmaster.com/#nord-lock-washers/=gcjv0z

Yes, those are effective as well.
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Old 02-21-2012, 12:04 PM
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Default RE: loose pitts style muffler on dle55

I used red loctite which is good to 500 degrees. Do you know the temp of the exhaust gas?
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Old 02-21-2012, 12:06 PM
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Default RE: loose pitts style muffler on dle55

thx BH

http://www.youtube.com/watch?v=mgwmuZuJ02I
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Old 02-21-2012, 02:57 PM
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Default RE: loose pitts style muffler on dle55


Quote:
ORIGINAL: SWORDSN

I used red loctite wich is good to 500 degrees. Do you know the temp if exhast gas?
It's around 550F as it exits the engine exhaust port. Your bolts see that amount of heat especially on hot summer days.

I use Nordlock washers and Permatex Ultra Copper rtv super high heat. This particular rtv is good to around 650 continuous and over 700 intermittent. I also use it on the threads of the bolts. Easy on and easy off without heat.
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Old 02-21-2012, 04:03 PM
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Default RE: loose pitts style muffler on dle55

I had trouble keeping a muffler on a DA50. Did the same as MTK, Nordlock washers, Permatex copper rtv, plus safety wired the bolts. Don't have a hugh number of flights with this setup but it has worked so far. Previously the muffler would loosen up after a couple of flights.
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Old 02-27-2012, 06:01 AM
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Default RE: loose pitts style muffler on dle55

Well I tried the above solutions with the same results. Nord-lock washers and all .Three flights and the muffler was loose again. This muffler is made of alum. Does anyone know of a steel muffler made for this engine?
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Old 02-27-2012, 06:47 AM
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Default RE: loose pitts style muffler on dle55

The problem here is the engine is just running too hot. For going on 15 years running gassers, I have cleaned the threaded holes in the engine and the bolts with acetone. Then apply red Loctite. The only time I have had issues with the muffler coming loose is when the engine was run too hot. If you are running a pitts type muffler I would also strongly suggest a strap running from the muffler to a mounting lug as it seems that just the 2 screws just arent enough. On a side note, you may want to verify that the muffler screws you are using are 5mm and not 10-23 for the DLE. DA uses 10-32. I know you have had them heli coiled but I see where other people could easily make this mistake as 10-32 will thread into a 5mm tapped hole however is not going to stay there for very long with any kind of heat cycle.
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Old 02-27-2012, 08:01 AM
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Default RE: loose pitts style muffler on dle55

+1
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Old 02-27-2012, 08:14 AM
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Default RE: loose pitts style muffler on dle55

Thanks for the info. The coils were put in by a pro so im sure they are metric. I did clean with alcohol. I don't think it is running hot since im running with the cowl off I have noticed that the coils are not as deep as the DLE threads. I may have to install new head.
The brace is a good idea to try. Tkanks
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