Procedure for Replacing the Pump Control Valve on Certain Mini Hydraulic Excavators{5455} Caterpillar

Mini Hydraulic Excavator:

305C CR (S/N: HWJ1-UP)

303.5C CR (S/N: DMY1-UP)

303C CR (S/N: BXT1-UP)

304C CR (S/N: FPK1-UP)

Introduction

The 279-4712 Pump Control Valve Gp can leak on certain 303C CR, 303.5C CR, 304C CR and 305C CR Mini Hydraulic Excavators. The leak is due to an error in the machining process.

Machine Requirements

Table 1 lists all of the affected machines.

If your machine leaks at the pump control valve, replace the pump control valve. Use the procedure that follows. Refer to Table 2 in order to determine the repair kit that is needed for the machine.

Note: Cleanliness is an important factor. Before the procedure, the exterior of the components should be thoroughly cleaned. This will help to prevent dirt from entering the internal mechanism.

Removal Procedure

1. Place a suitable piece of material in a location that is suitable for setting down the rear door and the cover that holds the fuel filler cap. These items will be removed as an assembly and a place must be provided in order to store the assembly without damage.

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Illustration 1	g01595888

2. Refer to Illustration 1. Open the door for the engine compartment and locate the four bolts (1) and (2). Mark the positions of the bolts and the mounting bracket. This will help with adjusting the door when you reinstall the door.

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Illustration 2	g01595891

3. Refer to Illustration 2. Remove the fuel filler cap (3) and remove the seal (4). Use a blunt screwdriver or a similar tool to lift the edge of the seal. Remove the seal.

4. Support the weight of the door and remove the four bolts (1) and (2). Grasp the door and the side cover together and remove the assembly by pulling backward. Place the assembly on the material in order to prevent damage.

5. Assemble the seal (4) and the filler cap (3) to the fuel filler assembly.

   Note: Steps 6 and 7 that follow are optional. On 303C CR and 303.5C CR machines, space is limited. It is easier to remove the fuel filler assembly. On 304C CR and 305C CR machines, there is more space and it is not necessary to remove the fuel filler assembly.

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Illustration 3	g01595893

6. Refer to illustration 3. Remove the two bolts that secure bracket (5) .

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Illustration 4	g01595898

7. Refer to illustration 4. Mark the position of the filler tube and loosen band clamp (6). Remove the filler tube. Place the parts aside in a clean location.

8. Cover the filler hole with a clean cap in order to prevent contamination.

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Illustration 5	g01595899

9. Refer to illustration 5. Open the side cover and locate the hydraulic overflow hose (7). Connect a vacuum pump to the open end of the hose and run the vacuum pump.

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Illustration 6	g01595900

10. Refer to illustration 6. Note the orientation of the fittings that join the following hose assemblies to the valve: (8), (9) and (10). Make sure that you collect spilled oil with shop towels when you disconnect the three hose assemblies. Plug the open ports in order to prevent contamination.

11. Loosen and remove four screws (11) that secure the valve to the pump. Remove the valve from the pump.

Assembly Procedure

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Illustration 7	g01595903

1. Refer to Illustration 7. Check the color of the band (12) on the new pump control valve. Refer to Table 3 in order to determine the necessary band for your machine.
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   Table 3

   Sales Model	Color of Band
   303C CR	Pink
   303.5C CR	White
   304C CR	Blue
   305C CR	Black

2. Transfer the fittings from the old pump control valve to the new pump control valve. Use the same orientation. Use new O-Ring Seals.

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Illustration 8	g01595906

3. Refer to Illustration 8. Remove the tape from the mounting face of the new pump control valve. Clean the mounting face thoroughly and make sure that the five O-Ring Seals are in place.

4. Make sure that the mounting face on the pump is clean. Assemble the new pump control valve to the pump. Make sure that the five O ring seals are not dislodged. Tighten the four screws (11) evenly to a torque of 12.7 N·m (9 lb ft).

5. Assemble the following hose assemblies to the pump control valve: (8), (9) and (10). Use new O-Ring seals.

6. Stop the vacuum pump and disconnect the vacuum pump.

7. Install the filler tube and clean up any spilled oil.

8. When all of the hoses have been correctly installed, start the engine and operate the upper structure slowly in both directions in order to remove air from the system. Exercise all of the hydraulic functions at slow speed through the full stroke of the respective cylinders.

9. Stop the engine and check for leaks.

10. Reference the marks in order to install the rear door and the side cover. Make sure that the door opens and that the door closes correctly.

11. Install the seal (4) and the fuel filler cap (3) .