2003/07/01 Caterpillar

Engine:

G3306 (S/N: G6X1-UP; 07Y1-UP; CTT1-UP)

G3408 (S/N: 6NB1-UP; 6RJ1-UP)

G3408C (S/N: 3WR1-UP; 6FW1-UP; BAZ1-UP)

G3412 (S/N: 7DB1-UP; 3NK1-UP; CTP1-UP)

G3412C (S/N: 6ZM1-UP; 8LW1-UP)

Description of Change: New auxiliary water pumps have improved oil seals and improved water seals that are more resistant to wear and to leakage. The new pumps have a hardened shaft that is more resistant to wear. The new pumps also have a threaded impeller that uses a jam nut in order to better retain the impeller on the shaft. All of these changes will improve the service life of the pump for the separate circuit aftercooler (SCAC).

The improved water seal is provided with Special Instruction, REHS1683, "Installation of the 227-9848 Seal " for proper installation of the seal.

Adaptable To: The new SCAC water pumps that are direct replacements for the old pumps are listed in Table 1 and Table 2:

Table 1

G3306
Description	Old SCAC Pump	New SCAC Pump
	Part Number	Part Number
Pump Assembly	116-1856	227-9850
Shaft	116-1855	227-9854
Impeller	1N-8321	227-9853

Table 2

G3408 and G3412
Description	Old SCAC Pump	New SCAC Pump
	Part Number	Part Number
Pump Assembly	9Y-7472	227-9843
Shaft	9Y-1278	227-9847
Impeller	8L-4041	227-9846

If you order the old SCAC pump shaft or the old SCAC pump impeller, you will receive all of the components that are required in order to replace the shaft and the impeller. If you are ordering the old 9Y-1278 Shaft for example, you will receive the following components:

• 227-9847 Shaft

• 227-9846 Impeller

• 227-9851 Lockwasher Set

• 235-4546 Jam Nut

Table 3 lists the serial number effectivity of the engines that are equipped with the new SCAC water pumps:

Table 3

Serial Number Effectivity
G3306	G3408	G3412
(S/N: 07Y9173-UP)	(S/N: 6NB2514-UP)	(S/N: 7DB1802-UP)
(S/N: CTT233-UP)	(S/N: 6RJ95-UP)	(S/N: 6ZM512-UP)
(S/N: G6X327-UP)	(S/N: BAZ190-UP)	(S/N: 8LW226-UP)
	(S/N: 6FW316-UP)	(S/N: CTP280-UP)