I have owned this engine for a while and its been put through the ringer. i just recently mounted it on a skyraider low wing and during engine run up i noticed the exhaust (aft end) begin to rotate. So i removed that section and put some thread locker on and put it back togther. well it is still backing itself off. just wondering if anyone else has had this same problem and what can be done to correct it. the engine doesnt seem to be vibrating more than normal so im not sure what the problem is. thanks

Did you clean the threads and nut before applying thread locker? I would imagine the exhaust residue would have a negative effect on the thread locker.

The exhaust loosening is a pretty common problem. Just be sure to clean all threads, apply thread locker, and tighten them back firmly.

I took some rubbing alcohol to the threads, nut and exhaust let them sit for a few then reattached. still no joy.

Loosen the nut on the back of the muffler, then tighten the screw head at the front. Then re-tighten the nut at rear.

J

You stated that it doesn't seem to vibrate more than normal. However, I would remove the prop and check its balance. It might be vibrating just enough to cause the problem without noticing. Ditto on Jburry's comment... everything must be tight.

Clean the threads super good, let dry, add locktote then reinstall the bolt and nut. Then if you can, double nut the end-problem solved. Also check the balance on the prop.

Cheers

Curt

I think that I might get some copper rtv and try to use that as a thread lock on the screw and where it attaches to the forward part of the muffler. Double nutting it sounds like a great idea as well. This engine is giving me all kinds off running problems as well..........frustrating.

You need to tighten the screw where it attaches at the rear of the muffler, the front isn't threaded. Then snug down the bolt at the end of the muffler. A lock nut on top of it is also a good idea. Tighten the screw first.

Yeah Jim I did tighten that down, it still came loose after. Tomorow I amd going to head out to the hard ware store and pic up so lock nuts. ill let you all know how I make out.

If you are getting excessive vibrations and running problems that weren't there before, has the motor been involved in a crash or mishap? If it was it could be a slightly bent crank. Also check your bearings for play, they may need replacing also. What color locktite are you using?? I use the Blue medium. Green is the weakest and Red is the strongest.

Curt

Did you try tightening the screw at the front? It is different than the nut on the back. Try doing as Jburry suggested.

Yeah I did tighten the screw at the front. I was using blue locktight but today I am going to try using copper rtv, we shall see what happens, mabey once that is fixed I can move on to the other problem with this engine...........it doesnt like to stay running. I honestly believe that it is a related problem, whener it the exhaust starts to rotate the engine begins to surger then quits. hopefully it cures all my problems........including a nagging girlfriend who wants me to do housework before I go flying!

Try some high heat silicone on the threads then tighten down that should cure the problem.

As everyone has indicated, the screw at the front actually provides the pressure to hold the back part of the muffler in place.

The nut at the back is merely used as lock nut, and doesn't do the real "work".

However, threadlock, etc. is all just a stop-gap measure...

Instead fix the problem altogether by drilling a small screw hole at the junction between the front and the back.

Clean out any debris then tap the hole and insert a locking screw.

No more rotation ever again.

While you have the muffler open, I would remove the baffle. Did on all my evos and don't have any issues after that.

flynte

hmmm thats a good idea, i wasnt sure if it would cause any running problems. i will def consider it. never did make it to the hardware store today. the sofa was much more inviting.

So Today I was able to fix the problem. Picked up a brand new one piece MACS muffler. problem solved. I liked it so much I also got one for my .55 ax. sounds mean, cant wait to fly em.

I found this problem in my evolution tps it seems to be a very common problem