Exhaust gaskets are one-time use components. Made from aluminum thread that is woven into a mesh, the gaskets deform upon compression by the exhaust pipe and flange. Round in shape but triangular in cross-section, the outer peak of the triangle receives the pipe end and seals against it as the gasket is crushed.
1 Inspect the pipe with the leaking Exhaust Gasket carefully before attempting to disconnect it. Front-pipe-to-manifold Exhaust Gaskets often require the rear Exhaust Gasket to the converter or pipe be separated in order to access the leaking gasket. Sometimes unhooking an exhaust hanger somewhere down the exhaust stream might allow enough flexibility to forgo the rear Exhaust Gasket disconnection.
2 Determine how the Exhaust Gasket is connected. All front-pipe-to-manifold Exhaust Gaskets are secured by nuts to the studs of the manifold. Downstream Exhaust Gasket connections may use studs on one side and nuts on the other or simple nuts and bolts. Downstream studs can be distinguished by round heads which, unlike a hex bolt head, cannot be held with a wrench. Studs have grooved notches in their shafts and do not require a box-end wrench for removing the nut. Nut and bolt connections will require the bolt of the head be held stationary (with the wrench) while a ratchet and socket loosen the nut (or another wrench).
3 Disconnect the Exhaust Gasket hardware. If necessary, heat the nuts of the connection with an oxyacetylene torch. Using a portable propane torch may not heat the nut up enough or could take a considerable amount of time. Heat just the edges of the nut and not the bolt. This will expand the nut. Once the nut is cherry red, turn off the torch and remove the nut. For front pipes, a ratchet, long extension and socket are most likely required.
4 Repeat for each nut and stud/bolt connection of the Exhaust Gasket until all retaining hardware is removed. The studs will remain intact on their respective exhaust components.
5 Separate the Exhaust Gasket connection. This is where the exhaust pipe hanger tool may come in handy. Releasing one or more exhaust hangers near the Exhaust Gasket connection may give the exhaust system enough flexibility to access the mating surfaces of each mating Exhaust Gasket. As mentioned earlier, it may also require separating the other connection of the exhaust component with the compromised Exhaust Gasket.
6 Clean each Exhaust Gasket connection’s mating surface with emery cloth or medium-grit sandpaper, after allowing the exhaust system to cool down, if a torch was used.
7 Apply a level amount of high-temp Perma-Tex (O2 sensor-safe) compound on both sides of the gasket. Place the gasket between the Exhaust Gaskets. On most Exhaust Gasket connections, there’s a small piece of pipe protruding on the inside of the Exhaust Gasket to place the gasket on, depending on the type of application. Some front pipe gaskets are called “donut” gaskets and fit into a ball-flared exhaust pipe.
8 Reconnect the Exhaust Gasket connection, after replacing the system on hangers, if applicable, with new hardware (nuts, bolts, washers and lock washers).
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