I have been unable to keep my muffler tight on each and every flight. This engine is very smooth running from idle to full throttle. There is no shaking of the airframe at anytime. As most of you know the bolts recess into the muffler. I installed the muffler with stock gasket and lock-tight (Red) and flew for ten minutes. Checking the muffler I found it very loose and the gasket destroyed. Muffler had damage around the mounting flange. At home I smoothed the flange with a file and made a new gasket out of material that worked OK on other types of engines. Same thing as previous flight.

Time for a new approach to this problem. I started thinking about safety wire. I decided to use a 3/16 aircraft grade aluminum plate with longer socket head bolts. I drilled the holes for the wire and installed. For the gasket I used the copper RTV by Permatex. Neat installation and I thought this would solve the problem. Short ten minute flight and checking the muffler, yes loose again but not as bad. I had to file the muffler again to smooth the flange. I was at a funfly yesterday and none could come up with a better plan than mine.

I have never had this problem with any of my engines, gas or glow. Thanks for any help you can give me.

My 3.7 came with safety wire--never had a problem. Hard to figure-- I would call Bill

The gasket can't compress if it's not in there..Use Permatex Ultra Copper silicone and no gasket, keep the safety wire.....And brace the other end of the muffler, either to the engine or the firewall...

Radar,
I have Taurus 2.6 that has the exact same problem. My muffler actually came off in flight but was held in by the cowl. I think high temp lock tight would do the trick however, I am not sure you could ever break the bolts loose again. That's why I haven't tried it. I tried the medium strength and it held for 2 flights but when I set it downl on the second flight it was coming loose again.

I like your approach and am surprised it didn't hold. Let us know what you find that works.

The 4.2 muffler is designed to have the socket head screws recessed into the muffler down at the exhaust flange, is it not? You mentioned longer bolts and it looks like you installed them with washers on the outside of the muffler housing? The long bolt setup is not the answer. Think about you are unable to really tighten the flange as you are actually compressing the muffler housing which is welded to the flange.

I have six Taurus Engines and have never had a problem with the Taurus exhaust system. 2.6, 3.2's, 3.7's and a 5.7.

I don't use Loctite it's kinda self defeating, what breaks down thread locking adhesives, heat! The high temp adhesive may help but you'll need to note the working temps. I just don't feel it's required.

I don't use a gasket either the Ultra temp silicone in place of a gasket and metal strap Ralph mentioned is a must to secure the muffler. Apply a light film of the silicone to muffler and allow it to tach up, then install and snug the bolts very lightly. Allow the silicone to dry for an hour or so and then torque down the bolts. Warm up the engine, tighten the bolt's and do it again. Remember there are several dissimilar metals interacting here. Heat cycling will help allow things to settle in.

I also use internal serrated star washers. Like those that come with the metal gear servos on the SHCS.

There are other lock washers, called high collar, the same diameter as the head of the bolt..

Something that was mentioned, but not stressed enough is to be sure that the support bracket is attached and keeping the muffler secure.

I have used teflon tape on exhaust bolts with great success.

I want to thank each one of you for sending me your suggestions. They are great and I will let you know what works. One thing for sure I will install a brace. You would think one with come with the engine from the factory.

Looking at the front of the engine, you will note a black socket head screw on the cannister, logic would dictate a possible bracket. that being said , since all installations vary how would the factory know what size bracket to supply.
Now the muffler weighs aproz 13 ozs and a good part of it hanging back, the first time it loosened up (lacking bracket) the steel bolts (hard) moved in the (aluminum) holes loosening up the fit. No amount of tightening will solve the problem. possible solution.
1) make a bracket
2) use stainless steel SHCS (different expansion rate)
3) because of the slightly oversize screw holes you might consider the next size to tap the existing holes(either metric or SAE)
4) clean out the holes with alcohol put some J B Weld in there and retap.
or as a last resort swallow your pride and call the factory.
in any event good luck.

I know I'm a bit late here but this is just about the only post I can find regarding the Taurus 4.2
Can anyone tell me what thier experiences are with the performance of the engine relative to it's class.
Thank you in advance, Bob