1998/07/01 Caterpillar

3304 (02B18151-Up, 04B27281-Up, 10E5405-Up, 37Y3596-Up) Industrial Engines, 3304B (13E1392-Up, 1PS591-Up, 1NS523-Up) Marine Engines, 3304B (9HK434-Up) Generator Set Engines, 3306 (23C26313-Up, 66D50838-Up, 64Z26313-Up) Industrial Engines, 3306B (1RS602-Up, 84Z3129-Up) Marine Engines, 3306B (2AJ1199-Up, 8JJ446-Up, 9NR2800-Up, 85Z14305-Up) Generator Set Engines, G3306 (07Y6702-Up) Engines

Description of Change: New basic water pump groups are used in the these commercial engines. The new basic water pump groups include:

* A new silicon carbide "unitized" (single-piece) water seal.

* A new lip-type oil seal with a dust lip for reduced water and oil leakage out the weep hole.

* A new hardened stainless steel water pump shaft to help prevent lip seal wear and shaft breakage.

* A new stronger water pump impeller. The new impeller has a "webbed" rather than round shape to help reduced rotating inertia and lower the stresses on the impeller.

Adaptable To: The new and former basic water pump groups and the respective water pump groups are identified in the chart. The former basic water pump groups have been canceled and replaced by the new basic water pump groups. New new basic water pump groups are in effect as shown above.

In order to accommodate the new shaft water seal design, the water pump housing and impeller designs were slightly modified. As a result, the new 154-9291 Water Seal is not compatible for parts service in the former basic water pump groups. The new 154-3945 and 154-3946 Water Pump Housings are required for use with the new 154-9291 Water Seal and 155-8758 Impeller.

The new 160-0461 Impeller is the service replacement for the 7N-5910, 4W-9645, and 134-7422 Impellers in former basic water pump groups.

The 4W-3864 Water Seal and new 160-0461 Impeller must be used to service the former basic water pump groups. The new 149-0791 and 156-7088 Shafts and the new 154-4482 Oil Seal may be used to service the former basic water pump groups.