Description

The Cummins Rear Crankshaft Seal 3353978 is a precision-engineered diesel engine seal designed to prevent oil leakage at the rear of the crankshaft , protecting the flywheel housing and maintaining proper lubrication in Cummins diesel engines. This seal is a direct replacement for Cummins OEM part number 3804900 , making it ideal for rear main service, lower-engine repairs, and complete engine rebuilds. Manufactured from high-quality elastomer sealing materials , this rear crankshaft seal is engineered to withstand high rotational speeds, constant oil exposure, vibration, and extreme temperature fluctuations common in heavy-duty diesel engine operation. The precision-molded sealing lip maintains consistent contact with the crankshaft surface, helping reduce wear and provide long-lasting leak prevention. Designed for accurate fitment and dependable sealing , the Cummins 3353978 rear crankshaft seal helps maintain proper oil pressure, prevent oil contamination of the clutch or flywheel area, and protect internal engine components. Replacing the rear crankshaft seal during an overhaul or clutch service is strongly recommended to avoid costly oil leaks and unnecessary downtime. This seal is commonly used as part of a lower gasket set or as a standalone replacement in Cummins diesel engine rebuild and rear-end repair applications , including on-highway trucks, industrial engines, and heavy-duty equipment.