Description

The Cummins Rear Crankshaft Seal C3353978 is a premium OEM-spec sealing component engineered to prevent engine oil leaks at the rear of the crankshaft , where it interfaces with the flywheel or flexplate. Manufactured to precise factory tolerances, this rear main seal delivers reliable, long-lasting sealing performance in Cummins diesel engines . Rear crankshaft seals operate under constant rotation, heat, and crankcase pressure. The C3353978 seal is produced from high-quality, oil- and heat-resistant elastomer materials designed to withstand severe-duty diesel operating conditions. Its precision-molded sealing lip maintains consistent contact with the crankshaft surface, helping prevent oil leakage that can contaminate the clutch, flywheel housing, or transmission components. This seal is commonly replaced during rear main seal service, flywheel or clutch replacement, bottom-end resealing, in-frame overhauls, and complete engine rebuilds . Installing a new rear crankshaft seal during service helps restore oil containment, maintain proper lubrication, and prevent costly repeat labor. The Cummins C3353978 rear crankshaft seal is trusted by diesel technicians, fleet maintenance teams, and professional engine builders who require OEM-level fitment and dependable leak prevention.