ORIGINAL: BarracudaHockey
RTV to seal mufflers is a recipe for disaster. First, you don't need it. Second, if you use anything more than the very thinnest smear, it can/will fleck off and get sucked into the combustion chabmer during the intake portion of the stroke. If that happens it will snuff the glow plug immedately.
A properly faced muffler/engine joint doesn't need any gasket or RTV. If the surfaces aren't flat, then a thin smear of 5min epoxy will seal it without the issues of RTV
I dont see the argument that RTV kills glow plugs to hold water, at least with my experiences. I've never had a glow plug get snuffed out because I used RTV to seal any part of the engine. Every engine I own has a leaky muffler without any sealant on it. Whether it leaks from where the two halves meet, the end caps, or the flange at the exhaust port.... they all weep a little bit. I'm lucky I haven't lost a muffler or part of one. Since I used some black or orange RTV to seal the muffler, they don't come loose and leak anymore.
No offense, but epoxy would be the LAST thing (remember, this is my opinion) I would ever use to "fix" a leaky mating surface. What would happen if a little fleck of that epoxy got into your engine...? That would be more damaging to the glow plug than a little silicone rubber IMO.