This seal has hydrodynamic grooves in its sealing lip (see Illustration 1). These grooves move lubrication oil back into the engine crankcase as the crankshaft turns. There is an additional lip without grooves on the flywheel side of the seal. This lip acts like a dust lip to prevent small particles or debris from contacting the inner seal lip. The seal offers more durability than the former silicone rubber lip seal group. The 4W452 Crankshaft Seal Group is a direct replacement for the former 1N3216 Crankshaft Seal Group.
The 3300 Family of engines have an oil shelf on the flywheel housing and an oil slinger on the flywheel. When the flywheel housings are partially wet with oil, the single lip crankshaft seal is used. The oil shelf and oil slinger “throw” the oil away from the seal area. See Illustration 2.