I was running my engine for some break in and found that the muffler is working its way loose after some time. Can I use some gasket stuff to give the screws something to keep them from working loose or is there a better way?

Thanks

J

Use RED locktite. It is heat resistant, yet you can still remove them at a later date.

Theres two possibilities I know of... One is you can use some RTV silicon... The heat doesn't bother it and it generally keeps a pretty good bite on the screws... The other, is what us heli guys do.... Tighten it down good, then go up and fly around a bit to get the engine nice and hot.... Land, then tighten the screws down again.... I've RARELY ever had a muffler screw come loose after doing this, and BELIEVE me, a heli can shake a screw outta damn near anything!

Also, I myself have never had much luck with locktite on a muffler, even the red... Just doesn't seem to hold when it gets hot in my experience... I dunno may have just been me...

jrhelm,

First of all, get rid of the gasket. The gasket allows the muffler screws to loosen due to vibration. Use RTV in place of the gasket. It doesn't take much to seat the metal-to-metal surfaces. The clear 732 type is fine, but if you want to spend a little more, the high heat types will also work. Personally, I just use the clear.

Second, use locktite (red or blue) on the screw threads making sure they are as clean as you can get them. I generally use acetone for this. Let it set over night and you sould be good-to-go.

A silly question, maybe, but do you have lock washers behind the screw heads? What Ed said previously had been my experience as well, as the gasket gets wet and compresses, it allows the scew tension to lighten and vibrate loose. Personally, I do what rusirus suggested. Run it for a minute or two at full throttle so it gets hot, then tighten them again. I would not recommend red locktite as it will build up in the internal threads and may make future removal difficult if you don't chase the thread with a tap. I have had more trouble getting them loose when cold, after a "hot tighten-up" and had to run the engine so I could remove them. I don't use any gasket material or silicone sealer, since most muffler to engine surfaces are machined so smooth the gas pressure leakage is minimal.

Thanks for all the good suggestions!!

Mike,
I don't have lock washers there as the engine did not include them. perhaps that would also help as a fix.

j

RTV if too liberally applied can break off and get sucked back into the engine and foul the glo plug resulting in an immediate dead stick. Not so much a big deal on fixed wing but be aware.

As stated earlier, you really don't need anything more than clean surfaces and let the engine warm up enough to get everything up to temp then snug the bolts.

Locktite my make you feel better but most of the common brands will liquify under the heat and be useless anyhow.

fwiw, Loctite brand foruma 222 (purple) works pretty well for me. Most "blue" threadlocker is meant for larger bolts (larger than 1/4"), so it doesn't hold well on smaller bolts. Some red is also that way (Loctite makes a ton of different forumlas that are "red").

They have high heat, oil resistant forumlas that will easily handle anything our engines throw at it.

fwiw, I also ditch any gasket, use bare metal-to-metal, and usually use a split washer under the bolt head. Sure doesn't hurt any.

Dont tell the helicopter guy's that locktite blue doesn't hold well.

Yea I know they make all sorts but if you goto NAPA and ask for locktite your going to get plain ole blue locktite in most cases.

When I get a locktited bolt that won't come loose I heat it up a bit with a soldering iron. That is generally all it takes.