SEAL-LIP TYPE 4K7463 - Caterpillar

3406 Industrial and Marine Engines (90U, 91U)Reference: Engine News; January 16, 1985; Page 7; "New And Improved Gaskets In Front Housing Group And Accessory Drive Group".Certain 3406 Engines have experienced oil leakage between the front timing gear cover and plate and between the front plate and the accessory drive group. New gaskets have eliminated this problem. See the reference article. As an alternative to installing the new gaskets, a hollow dowel can be installed that creates an oil passage. This passage keeps oil away from the gasket joints. Refer to the "Procedure To Install Dowel" and the illustration.
Procedure To Install Dowel
1. Remove the air compressor and the accessory drive group from the engine.2. Drill and ream the oil supply hole in the timing gear plate, front cover and accessory drive bearing to a 9.34 mm (.368") diameter.3. Clean the oil passage by cranking the engine with the starter.4. Install the 1S9540 Dowel through the timing gear plate and into the front cover as shown in the illustration. Leave the dowel protruding 9.53 mm (.375") from the timing gear plate.5. Install the drive group and air compressor.
Location of 1S9540 Dowel.