O.S. Engine OS42525310 Replacement S-25 Silencer Gasket for RC Exhausts  [OS42525310]

Replacement Seal for S-25 Mufflers

This S-25 O-ring from O.S. Engine is an aftermarket replacement seal intended for silencers that accept the S-25 type ring. It is referenced with part numbers F-6020 and FSa-155 and supplied as a single sealing component to re-establish a good exhaust joint and reduce blow-by at the silencer interface.

To fit, remove the silencer and inspect the mating face for carbon or sharp edges, place the O-ring into its groove, and reassemble while applying even compression. Avoid twisting the ring during installation and perform an initial leak check once the engine is running.

Properly seated exhaust seals help preserve backpressure and can contribute to steadier idle and improved throttle feel on glow-powered models. Treat this O-ring as a regular consumable and replace when it becomes brittle, cracked, or deformed.