168-6800 Pilot Pump Not Available For Product Support Program Caterpillar

Problem:

Containment Service Letter PS20011 includes the replacement of the entire 168-6800 Pilot Pump Group. The demand for this pump group has exceeded the original projections of the program. Additional 168-6800 pumps are not available from the supplier and the inventory of this pump is now depleted.

Solution:

The defective pilot pump groups that are effective with the above listed models can be reworked into a 168-6800 Pump. The rework of the defective pumps is possible only if the 153-2902 Front Bearing has failed, and if the 153-2663 Front Shaft of the pump is not damaged. The rework procedure is explained below.

Illustration 1.

I. Installation of the new 153-2902 Bearing (refer to Illustration 1):

a) Discard the defective 153-2902 Bearing (A1) from the pump.

b) Loosen the 5W-5351 Nut (B).

c) Discard the 3E-4988 Washer (C) and discard the damaged Coupling (A2) from the Pump Shaft (D).

d) Clean the Front Pump Shaft (D).

e. If the Front Pump Shaft (D) is in good condition, install the new Coupling (A2), the new 3E-4988 Washer (C), and the new 5W-5351 Nut (B) onto Shaft (D).

f) Tighten the 5W-5351 Nut (B) to a torque of 55 ± 5 N·m (40 1 3 lb ft).

Illustration 2.

Illustration 3.

II. Installation of the new 145-4096 plate to the back of the pump ( refer to Illustration 2 and Illustration 3:

NOTE: Do not loosen the 153-2146 Bolts used to hold the pump sections together simultaneously.

a) Plug all openings of the hydraulic pump to avoid contamination of the hydraulic system.

b) Support the pump in a vise (for example at the mounting flange of the pump or the side faces of the priority valve).

c) Remove only one 153-2146 Bolt (A) on the lower side of the pilot pump (refer to Illustration 2).

d) Install the 16 mm (.63 in) threaded end of the 174-5185 Rod into the pump housing. Lock two M10 Nuts (8T-4133) together. Tighten the rod to a torque of 8 N·m (5.9 lb ft). The end of the rod should protrude approximately 36 mm (1.42 in) from the valve housing.

e) Remove the two 8T-4133 Nuts from the threaded rod.

f) Install the 3 mm (0.12 in) 175-0137 Shim and install one 8T-4133 Nut onto the end of the rod. Tighten the nut to a torque of 56 ± 4 N·m (41 1 3 lb ft).

g) Repeat steps c) through f) for the second 153-2146 Bolt.

h) Install the 145-4096 Plate (B) onto the rod ends as shown in Illustration 3. Tighten the other two 8T-4133 Nuts (A) to a torque of 55 N·m.

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