Usage:
3406B/C (3ZJ, 5KJ, 4CK) Truck Engines
Reference: "New Cast Iron Inlet Adapter And Impeller For Water Pumps, " in this issue.
Description of Change: New basic water pump groups are being used. These new water pumps use a new tapered roller bearing assembly. The former water pumps used ball bearings and a spacer. The new tapered roller bearings reduce the end play of the water pump shaft. Reduced shaft end play allows the coolant seal spring to maintain more consistent contact pressure between the rotating coolant face seal and the stationary coolant face seal. This will reduce coolant leakage out the external weep hole.
Illustration 1. Location of the ball bearings in the former water pump groups.
Illustration 2. Identification of components in the new basic water pump groups.
Adaptable To: The new 1025939 and new Remanufactured 0R3789 Basic Water Pump Groups are direct replacements for the former 4P9372 and former Remanufactured 0R2400 Basic Water Pump Groups with the non-metallic 7C5479 Impeller. The former basic water pump groups are canceled.
The new 1025941 and new Remanufactured 0R3790 Basic Water Pump Groups are direct replacements for the former 4P2152 and former Remanufactured 0R2856 Basic Water Pump Groups with the cast iron 9Y3778 or former cast iron 9Y5651 Impeller. The former basic water pump groups are canceled.
See the Reference Article for the proper use of the aluminum and cast iron inlet adapters used with the basic water pump groups.
The new basic water pump groups are in effect with 3406B/C Truck Engines 3ZJ31495, 5KJ7916, and 4CK8450. Illustration 2 and the chart identify the components in the new basic water pump groups.
NOTE: Until the new 1025946 Housing is available for remanufacture, the former 9N5034 Housing is being modified to accept the new 1028478 Bearing Assembly (tapered roller) in the Remanufactured 0R3789 and 0R3790 Basic Water Pump Groups. A 1031248 Spacer Plate is used between the modified 9N5034 Housing and the new 1025945 Retainer. For those areas where Remanufactured water pumps are not available, a Special Instruction is being prepared to explain how to modify the former 9N5034 Housing.