IGNITION SYSTEM GROUP 6L5761 - Caterpillar

Rear (4W452) Hydrodynamic Crankshaft Seal Group
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 4W452 Rear Crankshaft Seal Group is packaged with the wear sleeve installed into the seal. DO NOT REMOVE the wear sleeve from the seal for any reason. When the wear sleeve is removed from the seal body, the seal group cannot be used. Attempts to reinstall the wear sleeve will cause damage to the seal surfaces.
Illustration 1. Cross section of hydrodynamic seal.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.
Illustration 2. 3300 Rear crankshaft area.Front Single Lip Silicone Rubber (5S6296) Crankshaft Seal Group
Illustration 3 shows a seal with a single silicone rubber sealing lip.
Illustration 3. Cross section of single lip seal.Rear Double Lip Silicone Rubber (1W2556) Crankshaft Seal Group
The seal shown in Illustration 4 has double silicone rubber sealing lips. It is used in applications where the rear crankshaft seal area is totally covered or flooded with oil during operation. When the seal area has SOME oil present, the 4W452 Hydrodynamic Seal Group will perform adequately with the oil slinger design of the flywheel and flywheel housing.
Illustration 4. Cross section of double lip seal.Seal Usage
Most engine and vehicle applications will use the rear single lip hydrodynamic seal group. Vehicles listed in the chart should use the 1W2556 Double Lip Silicone Seal Group. Use the 4W452 Hydrodynamic Seal Group with all other models.
Seal Installation
For installation of the new hydrodynamic rear crankshaft seal, see Special Instruction, Form SMHS8396, "Installation of 4W452 Crankshaft Rear Seal Group."