muffler O-ring recommendation

[Scott Richlen]

My muffler O-ring is going south.  Is there a special kind of O-ring to be used or are their some specifications of type of O-ring for this muffler environment?  It's a PA-61 RE.

Thanks!

[Robert Zambelli]

Scott: try McMaster-Carr.
They carry a huge assortment of o-rings, including high temperature.

Bob Z.

[Scott Richlen]

Thanks!

[Dan McEntee]

 You want a high temp O-ring  and these are usually a red colored silicone, at least in industrial use in my experience. Some good hardware stores carry a good variety of o-rings, along with good auto parts stores. An industrial power transmission parts and supply place will carry them also and most will sell to walk in traffic in small quantity.
  Type at you later,
   Dan McEntee

[Dave Hull]

This chart may help, although for guys who memorized the trade names, the symbol system may cause you to have to looks things up....

https://www.gallagherseals.com/pub/media/magefan_blog/2015/11/templimits.jpg

My first thought was Viton, if you weren't getting long enough life out of a silicone seal.

[Lauri Malila]

Silicone O-rings seal well but cannot always tolerate the mechanical loads. Viton is stronger and harder but it tends to permanently deform and harden under heat & compression.
So, both will work when done correctly. In both cases, I'd recommend replacing the O-ring with a new one every time you dismantle the system.
also, when you re-assemble the engine/muffler, it's a good thing to wrap a couple of layers of thin PTFE plumbing tape around the O-rings.
I make my own muffler adapters with 2 O-rings; the first (closer to engine) in Viton and the second in silicone. Viton takes the pressure loads, and silicone protects the Viton from direct contact with hot gases. L