Cummins 3903380 Banjo Connector Seal

The Cummins 3903380 banjo connector seal is a copper sealing washer designed for the injector fuel return line banjo fittings on Cummins B and C series diesel engines. It creates a fluid-tight seal between the banjo bolt and the injector return manifold connection. The seal is manufactured to OEM dimensions of 6.00 mm inner diameter, 10.00 mm outer diameter, and 1.00 mm thickness. This part supersedes to Cummins 4942278 and cross-references multiple OEM and aftermarket numbers. Six seals are required per engine for complete injector return line sealing. Replace seals whenever the return manifold is removed to prevent fuel leakage and maintain injection system integrity. Compatible with Cummins 4B3.9, 6B5.9, 6C8.3, ISB, QSB, ISC, ISL, and QSC engine families used in commercial trucks, construction equipment, agricultural machinery, and industrial applications.