Description

The Cummins Rear Crankshaft Seal 3353978 is a precision-engineered sealing component designed to prevent oil leakage at the rear of the crankshaft where it interfaces with the flywheel housing. This seal is a direct replacement for Cummins OE part number 3804900 , ensuring OEM-level fitment, sealing performance, and long-term durability. Manufactured for Cummins diesel engines , this rear crankshaft seal is produced using high-quality, oil- and heat-resistant materials capable of withstanding constant crankshaft rotation, engine vibration, and extreme operating temperatures found in heavy-duty diesel applications. The precision-molded sealing lip maintains consistent contact with the crankshaft flange, helping retain engine oil, prevent contamination of the clutch or flywheel assembly, and protect surrounding components. Proper rear crankshaft sealing is critical for maintaining oil pressure and preventing costly oil leaks during engine operation. The Cummins 3353978 rear crankshaft seal is commonly replaced during lower engine resealing, clutch replacement, flywheel service, and complete engine rebuilds . Supplied as one complete seal, it is ready for professional installation and is commonly included in Cummins lower gasket sets.