exhaust donut gaskets

[jeeptorino68]

separate issue from my other thread. but same jeep . 2002 3.7 with 226,000
i replaced both catalytic converters and i have a muffled exhaust leak. the typical downstream kind you get from a leaky donut gasket or flange.
i used a felpro gasket on the passenger side. the fit was good. but the walker cat on the driver side came with a gasket instead of metal on metal like the OEM cat.
the gasket but a lose fit around the cat. converter pipe. i read some posts about people putting a slit inthe donut. but unsure if this is for the driver or passenger side.

any help?

 

[CWBenjamin]

Same, walker cat, weird metallic clay-like donut, exhaust leak from donut gasket. Wonderin if there is a better gasket / fix.

 

[jeeptorino68]

Still working on mine so I dont have a fix yet. But I cut through it in on spot so I could pull it to a smaller circle. We will see

 

[jeeptorino68]

Thinking I will use this:
Permatex 81878

https://www.oreillyauto.com/detail/...ature-rtv-silicone-gasket-maker/81878/4610391

 

[CWBenjamin]

Hey, I bought some muffler cement and used it around the donut and the two end pieces to add some filler into where it needs to seal up and to create a smoother surface where the flange was all rough and rusted from the old wire mesh gasket... It seems to have worked. The kind I got seems to be great, but im sure any muffler cement will work. They sell the kind I got in a bigger bottle for 7 bucks at advanced auto, or autozone sells a smaller bottle of a different brand. All the gaskets I saw were only rated to 400-500 degrees and everyone said they would just burn off eventually... As long as you are using the cement on a part you are clamping together or using muffler wrap over it should be as permanent of a fix as you can rig.