Cummins 3948578 Valve Stem Seal (Inlet/Exhaust Valve Seal)

The Cummins 3948578 Valve Stem Seal (Valve Stem Seal) is a key sealing part of the engine's valve train, used to prevent engine oil from entering the combustion chamber, reducing carbon deposits and smoke. This oil seal is suitable for Cummins ISC 8.3L, ISL 8.9L, QSC 8.3L, QSL 8.9L series diesel engines, and is also compatible with 6C/6CT models. Made of high-quality fluororubber (Viton), with a top hat design, it ensures long-lasting sealing performance under high temperatures. 12 seals are required per engine, making it an essential part for engine overhaul or routine maintenance. It can replace OEM numbers 3943888, 3943889, 5253590, etc. Widely used in construction machinery such as excavators, loaders, and heavy trucks.