REAR CRANKSHAFT SEAL

The PAI 336012 Rear Crankshaft Seal (offered by Wofford Truck Parts) is a premium aftermarket replacement for the rear main seal position on a wide range of heavy-duty Caterpillar engine families. According to the product specification, it has dimensions: free ID 6.06″ (≈153.92 mm) × OD 7.34″ (≈186.43 mm) × thickness 0.75″ (≈19.05 mm).

It is designed for engine families including the CAT 3400 / 3406 / 3406E / 3408 series, and the C15 / C16 / C18 series engines. The seal replaces OEM CAT part numbers such as 142-5868, 2W-1734, 4P-2734, 130-8107, thereby providing a direct fit for engine rebuilds or maintenance installations.

Because this seal addresses the rear crankshaft interface, proper installation is critical to avoid oil leaks, ensure crankshaft end-play and maintain correct lubrication. PAI states this is a heavy-duty elastomer seal with reinforced sealing lip for exposure to crankcase oil and high temperatures. Before installation, users should confirm the rotation direction of the crankshaft (the spec states “Counter-Clockwise rear crankshaft rotation” for the listed family) and dimension match with the original.

Installation tip: Clean the crankshaft journal and seal housing thoroughly, inspect for wear or scoring, and apply the correct lubricant or break-in coating from the engine builder’s specification. If the old seal leaked, inspect the crankshaft snout, key-way and housing for wear before installing the new seal.