ISSUE DATE:
SERVICE BULLETIN SUBJECT:
VINs or MODELS AFFECTED:
COMPLETE BY:
SERVICE BULLETIN #:

12/17/2019
Catalyst 35 Power Steering Noise Reduction Retrofit
Service Specified Catalyst Buses
Next Service Opportunity
SC-19-161

POWER STEERING NOISE REDUCTION RETROFIT
NOTICE! It is expected that this process will require 4 hours per bus. Please
schedule appropriately to minimize vehicle downtime.

Retrofit Description:

This retrofit upgrades the power steering system to reduce the operational noise level of the system.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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Tools/Parts Required
Tools and Supplies Required:
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Wheel Lifts
4 EA
Jack Stands
4 EA
Transmission Jack
Catch Pan
Ratchet
13mm Socket
15mm Socket
16mm Socket
9/16-Inch Socket
13mm Combination Wrench
15mm Combination Wrench
17mm Combination Wrench
1-Inch Combination Wrench
1-1/2 Inch Combination Wrench
7/8-Inch Combination Wrench
7/8-Inch Crow’s Foot Socket
1-Inch Crow’s Foot Socket
1-1/2 Inch Crow’s Foot Socket
Flat Blade Screwdriver
Hose Clamp Pliers
Side Cutting Pliers
Calibrated Torque Wrench
Orange Torque Stripe Paint
Funnel

Parts Required:
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044166
TANK, POWERSTEERING
044870
FITTING, MALE, 90°, 1/2 JIC, SAE #8, LONG
044871
FITTING, HYDRAULIC, 90 DEGREE
045994
FLEX LINE, POWER STEERING
045995
BRACKET, POWER STEERING
051490
HOSE, PUSH LOK, 1"
051491
FITTING, PUSH LOK, 1"
045993
FLEX LINE, POWER STEERING
020891
WASHER, DIN 9021, SST, M8
012138
WIRE TIE, HEAVY DUTY .5WIDE 9.1" BLACK
Dexron VI Automatic Transmission Fluid (Obtain Locally)
Loctite 567 (Obtain Localy)

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

1 EA
1 EA
1 EA
1 EA
1 EA
2 FT
2 EA
1 EA
2 EA
2 EA
3 GL

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Procedure
1. Perform the Proterra approved Lockout/Tagout procedure for safety. Refer to the Proterra
Catalyst LOTO Safety Guide if you are unsure of the proper procedure.
2. Using Wheel Lifts raise the bus. Use four Jack Stands to support the bus after it is lifted.

Safely Raise
and Secure
the Bus

3. Using a 13mm Ratchet/Socket and a 13mm Combination Wrench, remove the front bumper.

4. Place a Catch Pan underneath the power steering reservoir drain plug.
5. Some fittings in this procedure are National Pipe Thread (NPT) fittings. All NPT fittings require
Loctite 567 on the tapered threads. Failure to apply Loctite 567 will cause leaks.

Apply Loctite 567 to Tapered Threads

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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6. Using a 17mm Combination Wrench, remove the power steering reservoir drain plug and allow
the Power Steering Fluid to drain into the Catch Pan.

Remove Drain Plug

7. Using 1-Inch and 7/8-Inch Combination Wrenches, disconnect the hoses that connect the
Power Steering Pump to the reservoir.
Remove Hoses

8. Using a 15mm Ratchet/Socket, remove the two bolts that attach the reservoir to the vertical
surface of the bus body.

Remove Bolts

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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9. Using Hose Clamp Pliers, squeeze the Clamp on the fill neck so that it can be removed. Using
a 13mm Ratchet/Socket, remove the two bolts that attach the reservoir to the horizontal
surface of the bus body. Remove the reservoir.

Squeeze Clamp

Remove Bolts
Remove Reservoir

10. Using a Flat Blade Screwdriver, remove the four screws that retain the motor junction box
cover. Remove the cover.
Remove Screws and Cover
Strain Relief

11. Take photos or make notes to showing the proper wiring connection to the motor. Disconnect
the motor wires and pull them out of the strain relief.
12. Using 1-Inch and 7/8-Inch Combination Wrenches, disconnect the hoses that connect the
Power Steering Pump to the power steering gear.

Disconnect Hoses from 90 Degree Fittings

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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13. Using Side Cutting Pliers, cut the wire ties that secure the hoses to the bus body and discard
them.
Cut and Remove Wire Ties

14. Support the Power Steering Pump/Motor assembly using a Transmission Jack or other
approved lifting device. Using a 16mm Ratchet/Socket, remove the four bolts (circled in red
below) that secure the assembly to the bus body.

15. Lower the assembly from the bus and place it on a workbench.

16. Using a 9/16-Inch Ratchet/Socket remove the four nuts from the bottom of the assembly to
release the motor and isolators from the frame.

Remove Isolator Nuts

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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17. Remove the motor assembly from the frame.

18. Using 1-Inch and 7/8-Inch Combination Wrenches, remove the two hoses shown in the
following illustration. The other end of these hoses were connected to the steering gear.
Remove Hoses

19. Using a 1-1/2-Inch Combination Wrench, remove the 90 Degree inlet and inlet pipe fitting from
the pump.

Remove Fitting and Inlet Pipe

20. Using a 7/8-Inch Combination Wrench, remove the remaining fittings and pressure relief valve
from the pump. Leave only the 90 Degree fitting.

Do Not Remove this Fitting

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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21. Using a 15mm Combination Wrench, remove the two bolts that secure the pump to the
housing. Do not remove the pump from the motor shaft.

Remove Bolts

22. Rotate the pump counterclockwise to the position shown in the following illustration. Using a
15mm Combination wrench, secure the pump to the housing with the bolts that were removed
earlier.
40 Foot Pounds
Ports Oriented Horizontally
40 Foot Pounds

23. Using a Calibrated Torque Wrench with a 15mm Socket, torque the bolts to 40-foot pounds.
Mark the bolts with Orange Torque Stripe Paint.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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24. Using a 7/8-Inch Combination Wrench, install the components shown in the following
illustration on the 90 Degree Fitting as shown. These parts were removed previously and are
being reused. Using a Calibrated Torque Wrench with a 7/8-Inch Crows Foot Socket, torque
the Elbow to 42-foot pounds.

42 Foot Pounds

25. Using a 7/8-Inch Combination Wrench, install the 90 Degree Fitting (016606) and the Straight
Fitting (016538) as shown. Using a Calibrated Torque Wrench with a 7/8-Inch Crows Foot
Socket, torque these fittings to 42-foot pounds.

016538
016606

26. Using a 7/8-Inch Combination Wrench, install the 90 Degree Fitting (044870) as shown in the
following illustration. Using a Calibrated Torque Wrench with a 7/8-Inch Crows Foot Socket,
torque the fitting to 42-foot pounds.

044870

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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27. Using a 1-1/2-Inch Combination Wrench, install the 90 Degree Fitting (044871) onto the pump
as shown. Using a Calibrated Torque Wrench with a 1-1/2 Inch Crows Foot Socket, torque the
fitting to 112-foot pounds.

044871

28. Using a 7/8-Inch Combination Wrench, install the Flexible Hoses (045994) and (045993) as
shown. Using a Calibrated Torque Wrench with a 7/8-Inch Crows Foot Socket, torque the
hose end fittings to 40-foot pounds.
045994
045993
40 Foot Pounds (Both Fittings)

29. Using a 7/8-Inch Combination Wrench, install the Hard Line (016536) that was removed
previously as shown in the following illustration. Using a Calibrated Torque Wrench with a 7/8Inch Crows Foot Socket, torque the fitting to 40-foot pounds.

016536

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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30. Place the modified Pump/Motor Assembly inside the new Power Steering Bracket (045995).
Using a 9/16-Inch Ratchet/Socket, replace the nuts that secure the motor to the bracket.

Replace Isolator Nuts

31. Apply a small amount of Automatic Transmission Fluid to the inside of one end of the 1-inch
Hose (051490) and to the hose barb of Push Lock Fitting (051491) to lubricate them. Press on
one of the Push Lock Fittings into the lubricated end of the hose. The fitting must be inserted
into the hose until it is flush with the yellow ring as shown in the second illustration below. Do
not install the second Push Lock Fitting at this time. These fittings are permanent and cannot
be removed.

Lubricate Hose and Barb
Hose Flush with Yellow Ring
32. Using a 1-1/2-Inch Combination Wrench, attach the Hose (0051490) and Fitting (051491)
assembled in the previous step to the new Tank (044166) as shown. Using a Calibrated
Torque Wrench with a 1-1/2 Inch Crows Foot Socket, torque the fitting to 112-foot pounds.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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33. Using a 1-Inch Combination Wrench, install the new Hose (025623) as shown. Using a
Calibrated Torque Wrench with a 1-Inch Crows Foot Socket, torque the fitting to 54-foot
pounds.
025623

34. Using a 1-Inch Combination Wrench, remove the level sensor from the old tank and install it on
the new Tank (044166).
Level Sensor

35. Move the new Tank Assembly to the bus. Thread the hoses through the opening in the bus.
Place the Hose Clamp on the Filler Neck hose that is protruding through the bus body.
Carefully attach this hose with the Hose Clamp to the Filler Neck.
Note: It may be necessary to access the filler hose from inside the Driver Workplace if the
hose cannot be connected from outside the bus.

Hose Clamp

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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36. Using a 13mm Ratchet/Socket, install the two lower tank bolts that were removed earlier.
Using a 15mm Ratchet/Socket, install the two upper tank bolts that were removed earlier along
with two new Flat Washers (020891).
Washers
15mm Wrench
13mm Wrench

37. Using a Calibrated Torque with a 15mm Socket, torque the upper bolts to 15-foot pounds.
Using orange Torque Stripe Pain, mark the torqued fasteners.
38. Using a Calibrated Torque with a 13mm Socket, torque the lower bolts to 37-foot pounds.
Using orange Torque Stripe Pain, mark the torqued fasteners.
39. Connect the Tank Level Sensor to the bus harness.
40. Lift the Power Steering Pump/Motor assembly using a Transmission Jack or other approved
lifting device. Using a 16mm Ratchet/Socket, secure the assembly to the bus body using the
bolts that were removed earlier. Using a Calibrated Torque Wrench with a 16mm Socket,
torque the bolts to 74-foot pounds. Mark the bolts with Orange Torque Stripe Paint.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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41. Using a 7/8-Inch Combination Wrench and a 1-Inch Combination Wrench, connect the smaller
Hose (025623) to the fitting as shown in the following illustration.

Connect Hose (025623)

42. Using a Calibrated Torque Wrench with a 7/8-Inch Crows Foot Socket and a 1-Inch
Combination Wrench, torque the fitting to 40-foot pounds.
43. Carefully measure the length of 1-Inch Hose (051490) required to connect the Hose to the
pump using a Push-on Fitting (051491). The Hose should be cut long enough to allow it to be
seated flush with the yellow ring on the fitting, but not so long as to cause kinking. Using a
Tubing Cutter, cut the Hose.

Cut Hose

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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44. Apply a small amount of Automatic Transmission Fluid to the inside of the free end of the 1Inch Hose (051490) and to the barb on the Push Lock Fitting (051491) to lubricate them. Pross
on the Fitting into the lubricated end of the Hose. The fitting must be inserted into the hose
until it is flush with the yellow ring as shown in the second illustration below. These Fittings are
permanent and cannot be removed without destroying the Hose.

Lubricate Hose and Barb
Hose Flush with Yellow Ring

45. Using a 1-3/8 Inch Combination Wrench and a 1-1/2 Inch Combination Wrench, connect the
Hose (051490) and Fitting (051491) to the pump as shown in the following illustration.

46. Using a 1-1/2 Inch Combination Wrench and a Calibrated Torque Wrench with a 1-1/2 Inch
Crows Foot Socket, torque the fitting to 112-foot pounds.
47. Using a 7/8-Inch Combination Wrench, connect the pump hoses to the steering actuator as
shown in the following illustration. Using a Calibrated Torque Wrench with a 7/8-Inch Crows
Foot Socket, torque the fitting to 40-foot pounds.
Note: The bus body is removed for clarity.

Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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48. Using two Wire Ties (012138), secure the pump hoses to the bus body as shown.

Wire Ties

49. Reconnect the motor wiring according to the diagram that was created earlier. Using a Flat
Blade Screwdriver, replace the motor junction box cover and the four screws that secure it to
the motor.

50. Using a Funnel, fill the Tank with 3 Gallons of Dexron VI Automatic Transmission Fluid.
51. Leave the Fill Cap off the Tank.
52. Locate and remove Circuit Breaker CB-423 from the ECAB panel to disable the automatic ride
height system.
53. Remove the Wheel Lifts from the front of the bus.
54. Remove the Lockout/Tagout devices.
55. Enter the bus and power it on.
56. Turn the Steering Wheel back to its right and left limits several times to remove the air from the
system.
57. Check the Power Steering Fluid level and add additional fluid if needed.
58. Replace the Filler Cap.
59. Lower the bus.
60. Reinstall Circuit Breaker CB-423 in the ECAB panel to disable the automatic ride height
system.
61. Return the bus to service.
Headquarters: 1815 Rollins Road, Burlingame, CA 94010
East Coast Manufacturing: 1 Whitlee Court, Greenville, SC 29607
West Coast Manufacturing: 383 Cheryl Lane, City of Industry, CA 91789

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