Description

The Cummins Rear Crankshaft Seal 3353978 is a precision-engineered rear main seal designed for Cummins 6C 8.3 diesel engines . This seal is installed at the rear of the crankshaft to prevent engine oil leakage between the crankshaft and flywheel housing. Manufactured to OEM specifications , the Cummins 3353978 rear crankshaft seal is made from high-quality sealing materials engineered to withstand constant rotation, high temperatures, and continuous oil exposure common in heavy-duty diesel applications. Proper rear crankshaft sealing is critical to preventing oil leaks that can contaminate the clutch or torque converter and lead to costly repairs. This rear crankshaft seal is commonly included in bottom-end, lower, and in-frame gasket sets and is typically replaced during clutch service, flywheel removal, crankshaft repairs, and full engine rebuilds . Replacing the rear seal during service ensures a clean, leak-free assembly and long-term engine reliability. The Cummins 3353978 rear seal is ideal for professional diesel repair shops, engine rebuilders, and fleet maintenance operations servicing Cummins 8.3L engines.