PIN 7B6641 - Caterpillar

All 3406 Truck, Industrial, Maxine and Generator SetSUPPLEMENT: 01/31/83SERVICE MAGAZINE, NOVEMBER 1, 1982, PAGE 4.In the article, "New Crankshaft Seal Groups Used" the subtitle must be changed to read as follows: 3406 Truck, Industrial, Marine and Generator Set Engines. In the chart, the in effect serial number for 3406 Industrial Engine is not correct. The correct serial number is 90U19273.--------------- END SUPPLEMENT ---------------Reference: See the article "6V6142 and 6V6143 Installers Can Be Used To Install Crankshaft Seals And Wear Sleeves," in this issue.Description of Change: Two new crankshaft seal groups are now used on the above engines. The new seal groups have new seals and wear sleeves. The new seals are different in design from the former seals. The new seals are made from a different material and have hydrodynamic grooves in their lips. These grooves in the lips of the seals move lubrication oil back into the engine crankcase as the crankshaft turns. Because of the action of these grooves the front seal is different from the rear seal. These seals have a mark that shows the direction of crankshaft rotation. If a seal is used on the wrong end of the crankshaft, lubrication oil will flow out of the engine because the grooves in the seal are in the wrong direction in relation to the crankshaft rotation.
The material in the lips of these seals can be damaged very easily. Fingers, fingernails, wires or the edge of the wear sleeve can put a scratch on the surface of the seal lip.
These new seal groups come with the seal already installed on the sleeve. This is done to protect the lip of the seal and make installation easier. The seal and sleeve must not be separated from each other. If they are separated, both the seal and sleeve must be destroyed.
Adaptable As: The new 2W1733 (front) and 2W1734 (rear) Crankshaft Seal Groups are direct replacements for the 7N1999 Crankshaft Seal Group in these applications. Special Instruction, Form SMHS8008, comes with each new seal group. This publication has special handling and installation instructions for the new groups. The procedure for installation of these new groups is similar to the one shown in Special Instruction, Form SMHS7100.