Caterpillar 1N4320 Diesel Engine Intermediate Main Bearing

Caterpillar 1N4320 is the intermediate (center) main bearing for the D353 diesel engine, supplied in.025-inch undersize to restore journal clearance after wear. It features an outer diameter of 127.61 mm (5.02 in), designed to fit the engine block’s center main journal and support the crankshaft while minimizing friction between moving parts. The.025" undersize designation indicates this bearing is intended for rebuilds where journals have worn beyond standard tolerances, enabling precise clearance when paired with the corresponding journal dimensions. This part is specified for Caterpillar’s D353 engine line as the center/main bearing and is commonly cataloged in both official Cat listings and aftermarket catalogs under 1N4320 or M-1N4320 references in undersize form. Typical applications include restoration or overhauls of D353-based equipment where the center bearing requires replacement with a.025" undersize specification to achieve correct crankshaft end clearance and oil film stability. When ordering, verify the exact bearing location within the crankcase (intermediate/center) and ensure the journal sizes match the undersize requirement to avoid improper fit or oil clearance issues.