ORIGINAL: Jake Ruddy
There are actually 2 different types of red loctite.. one is rated at 300F and one 500F. I would bet the basic red starts to let go with constant heat at less than 300. A big part of it is vibration.. if you aren't dealing with that properly then red is not going to work unless its the high temp red.
I've always used the Loctite 271 which I believe is a lower temp rated red. It is rated at 50% strength at 300 deg. F. Of course there are extensive charts to show its strength at various temps and exposure times. I have never had a problem with this material holding even on exhaust bolts. When I finally remove my mufflers, the bolts always pop loose with a distinctive snap so I know the bond is still good. In most applications, I believe mufflers would stay in place just fine without Loctite if the user would just not use a gasket, insure good flat mating surfaces on the muffler and cylinder flange, clean the bolt and cylinder threads well and use good mechanical support on overly heavy (pitts style) mufflers. A very light coating of Permatex Ultra Copper on one mating surface assures leakproof seals. I don't like this stuff on the threads as I can't see where it holds much of anything .... it is a sealer - gasket maker, not an adhesive.
I always get a chuckle at local fields, some people can't keep mufflers on anything where others never have problems. Those that don't have problems give tips to those who do but they never seem to listen. Hmmmmm .... sounds just like the gas engine forum. [8D] Aquaskiman, I'm not directing this at you in any way .... just making a general observation. I have no way of knowing what caused your muffler loss.