Loose muffler

[fastone93]

Originally Posted by raylepper

I respectfully disagree on two points. I don't think our pipes reach over 450F and I have used Nylok nuts on my OS50 and 55 pipes where the internal threads are gone. They stay tight. Maybe I'm just lucky. My crash frequency would say I'm not, though. Having said that, I could certainly be wrong. Maybe somebody can use a temp gun this weekend and get the temp of the motor and the pipe. Would be interesting.

I tried this with a funtech pipe on my 600 and they melted and came loose the very first flight, lean run, new piston and ring.

head temp on a full scale airplane is +/- 350 degrees, exhaust temp is +/- 1300 degrees, almost 4 times higher.

Using this, the exhaust on a heli engine that has a head temp of 200 degrees would be around 750 degrees roughly. This comparison may not be 100% accurate, but I will promise you that the exhaust pipe connection on your heli is waaaaaaaaaaaaaaaaaaaay over 450 degrees.

[fastflyer20]

Alignnitro, it is best to get them relatively flat, a Dremel and a carbide bur makes it a quick fix.

[stephenwagner]

fast one,

The melting point of aluminum is 1220 deg F. Did you melt your muffler?

What makes you think the muffler came loose and caused your lean run?

Maybe your muffler became loose from a lean engine tune.

I have been flying for over 20 years with elastic stop nuts behind all my mufflers. Never had one melt. Never had one come loose. I also use heavy duty aluminum foil for muffler gaskets. Never one leak.

Here are my inputs. Tighten the x-long muffler bolts with a small 3mm driver. Make them snug and not tight. Put a small washer behind the muffler flange and then an elastic stop nut. Tighten the nut with a small 5.5mm wrench. Make the nut snug and not tight. Go fly and have fun. Check the nuts and bolts. If they are loose, well then, make them a little tighter next time.

I tune my engines for smooth operation, lots of mosquito killing smoke, 1800 RPM head speed and not max power. I even put an extra shim under the head. My OS 50 is three years old on the original bearings and rings. The top of the piston is like new. The inside cylinder head is like new and shiny. The rear bearing? zero slop. I prefer reliability over performance.

SJW

[Alignnitro]

Okay so if it isn't settled I think I can do so with this !! A lot of pro pilots including Tim jones uses this http://www.epoxywarehouse.com/pc-fah...tty-epoxy.html its called pc Fahrenheit. I know a lot of others have since used it after hearing Tim say it works great and never having a problem. Claiming its the best stuff to use. If you read the listing it says do not use on anything over 500 degrees.

[Brian4301]

Little update for any "newbies" like me.

Put on the locking nut, heated it up with couple minutes of flight, snugged down a little more and no problems since.

So for all the pro's out there with their help...

[Bengsch85]

Originally Posted by fastone93

I tried this with a funtech pipe on my 600 and they melted and came loose the very first flight, lean run, new piston and ring.

head temp on a full scale airplane is +/- 350 degrees, exhaust temp is +/- 1300 degrees, almost 4 times higher.

Using this, the exhaust on a heli engine that has a head temp of 200 degrees would be around 750 degrees roughly. This comparison may not be 100% accurate, but I will promise you that the exhaust pipe connection on your heli is waaaaaaaaaaaaaaaaaaaay over 450 degrees.

I temped it one day just out of curiosity. On both my 600N and my 1/8 scale nitro truggy the hottest part was the expansion chamber and it never seemed to be over 350F. But it may cool off quickly at idle before I could get a reading so that may be off. The header connection wad always about 50F cooler then the can.

[Inverse]

Originally Posted by raylepper

Melting temp of nylon is over 450 degrees F. Not sure if NYLOK nuts actually have nylon in them. But mine have never melted. Though I do try to keep my engine below 450F

How ca you be sure your nyloc nuts don't melt?
I know using a nylon cable tie on my exhaust pressure nipple is a no go as it melts and fails.
I just use a second piece of fuel hose over the the top and it doesn't come off now.
Been having all sorts of issues getting my pipe to not leak, I've just ordered some PC Fahrenheit high temp epoxy, some more M3 nuts, some star washers as well as just spending about 3 hours 'facing' the pipe and exhaust flange on the crankcase using a whetstone. They now mate up perfectly.
I'll be using the epoxy as a gasket and double nutting it with a star washer.
I don't care if I need an angle grinder to seperate them.

[Himilou]

Originally Posted by Brian4301

Longer bolts, nylon lock nuts. I burned one tank and snugged down a little more and all seems well.

The exhaust gets crazy hot, does that cause problems with the nylon in the lock nuts melting?

Just an observation

I've had mine melt, split loc washer and a nut is what works for me, quick afterthought though if you put the bolt heads on the muffler side and the nuts on the cooler crankcase side they might be ok. I had my nuts on the exhaust side