muffler gasket sealant?

I've always been of the belief that muffler gaskets should never have any kind of sealant. But more and more I am running into people who swear by things like RTV Ultra Blue, or RTV red... not AS a gasket, but in addition to a gasket.

I'm starting to find now that even with fresh gaskets my exhaust systems aren't sealing as well as I would like.

I am curious what GRMers think...

to sealant, or not to sealant?

on gaskets i have always made it a ritual to use either copper coat or copper rtv. sometimes in replacement of the gasket but often just to be sure it seal.... ultra blue would burn out right away.

ive used the copper rtv with success

gasket should seal by clamping force alone. IMO, any viscous coating: copper spray, aliminum hi-temp paint, anti-seize etc. will wet the gasket or donut and help deform it to the fit of the flanges.

Red rtv. I've cobbled lots of exhaust repairs, works.

All I know is a taiwanese 1.75" vs american 1.75" doesn't seal all that well. I have used copper tape to seat an exhaust but that isn't a great solutiion.

I know the turbo dodge guys use bearing grease (non synth) on the turbo downpipe flange and turbo flange to stop it from leaking...

Depends on the gasket type. White fiberus (header gasket to block) one get soaked in BOILING hot water for 5 minutes before being installed. It softens and swells the gasket and lets it form to the header better. Compressed metal coned type (look like brillo and lead) i normaly just make sure flanges are smooth and install dry. Metal flat like two bolt flanges get red RTV

If its a work in progress. All pipes get red RTV and 2 spot welds with very little clamp presure. This helps with removal down the road.

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How many sealing compounds will stand up to exhaust temperatures ?

iceracer wrote: How many sealing compounds will stand up to exhaust temperatures ?

I know Permatex Ultra Copper RTV has been sealing up my broken exhaust manifold, it is also missing one manifold to head bolt, for 30k so far..... I have had to replace it once because I couldn't stand the exhaust tick all the time.

DEI/Spal is selling a gasket eliminator that's specifically meant for turbo/exhaust applications.

http://www.designengineering.com/press/spa-turbo-usa-gasket-eliminator-and-flange-sealant