Kubota U48-4 U55-4 Injection Pump Unit Removal and Reassemble Guide

This illustration show steps on how to remove and reassemble injection pump unit for Kubota U48-4 U55-4 excavator.

 

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Procedures:

(Removing the fuel injection pump unit)

1.Detach the window cover (2) for the fuel injection pump unit from the flywheel housing.

2.Place the piston of the 4th cylinder at the top dead center in the compression stroke. Fix the flywheel with the flywheel stopper.

 

IMPORTANT

• Look for the alignment mark (6) on the idle gear and the injection pump gear. Using a white marking pen or the like,put an alignment mark (6) on the engaged tooth of the both gears. This helps to reassemble these gears in mesh later.

 

NOTE

• When the already existing alignment marks (6) align with each other, there is no need to put another alignment mark (6).

3.Unscrew the two plugs (3) of the injection pump unit.

4.Tighten the upper fuel camshaft lock screw (8) until it comes into contact with the fuel camshaft. Make sure the camshaft does not move any longer.

5.Tighten the lower fuel camshaft lock screw (8) until it comes into contact with the fuel camshaft.

 

NOTE

• Never overtighten the lock screws when they have come into contact with the camshaft. Otherwise the injection pump itself may get damaged.
• Use of a socket set screw (dog point type) is recommended for best results. Such screw can be constructed as shown in figure (a).

6.Disconnect the lubricating oil pipe (4).

7.Using a white marking pen or the like, put an injection timing mark (7) on the injection pump unit and on the crankcase 1.

8.Loosen the three injection pump unit mounting nuts (1).

9.Remove the injection pump unit support (5) and take out the injection pump unit.

 

(Reassembling the fuel injection pump unit)

1.Place the piston of the 4th cylinder at the top dead center in the compression stroke. Fix the flywheel with the flywheel stopper.

2.Install the injection pump unit to the crankcase 1.

3.Make sure of aligning the alignment marks of the injection pump gear (9) and the idle gear (10).

4.Take off the fuel camshaft lock screws (8) and tighten the plugs (3) for plugging.

5.Moving the injection pump unit clockwise (viewed from front cover side), align the injection timing marks (7) on the injection pump unit and on the crankcase 1.

6.Tighten the injection pump unit mounting nut (1) to the specified torque.

7.Reconnect the lubricating oil pipe (4) and place the injection pump unit support (5) and the window cover of the injection pump unit.

8.Remove the flywheel stopper.

9.Check the injection timing. (See the “Injection Timing”.)

10.If the injection timing is not within the specification, repeat “4.” to “9.” again.

 

More repair case for Kubota,please refer to:Kubota Trouble Repair