Relocation Procedure of the Engine Outlet NOx Sensor On Certain 834K, 836K, and 988K Machines{7490} Caterpillar

Introduction

The following Special Instruction covers the procedure for relocating the engine outlet NOx sensor. The NOx sensor location is being moved from the pre-bellow location to a post bellows location to reduce vibration.

Do not perform any procedure or order parts until you have read and understand the following procedure.

Parts Required

There are four different groups that take only certain parts that are listed in Table 1. Ensure that the correct parts are ordered for the appropriate groups. The effectivity for each group is listed below.

• Group 1 - TWX00150-00260, ; TWY00200-00301

• Group 2 - TWZ00250-00411

• Group 3 - TWX00261-00361, ; TWY00302

• Group 4 - TWZ00412-00432

Inspection and Rework of 464-1103 Harness As

The 464-1103 Harness As , in the above parts list, may have incorrect connector wire locations. Inspect the connector wire locations per the chart below. Rework the harness if required. If the harness wire locations are incorrect, numerous fault codes will be generated. Parts inventory rework is in process.

Illustration 1	g03799445

Use DT tool to remove wedge and move three incorrect wires. Fill position (2) and (3) with 8T-8737 Seal Plugs .

Installation Procedure

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Illustration 2	g03718625

1. Use the existing bosses, add the hardware and jumper harness.
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   Illustration 3	g03826963

   1. Install clips (28) using bolts (35) with hard washers (31) to secure the clip. Install clip (4) using bolt (33) with hard washers (31) to secure the clips.

   2. Secure the harness to the clips using cable straps (30) as shown in Illustration 3.

   3. Connect jumper harness assembly (24) to the connector.

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Illustration 4	g03827063

2. Install clip (4) onto the existing boss shown in Illustration 4. Route the jumper harness as shown in Illustration 4 using cable straps (30) to secure jumper harness (24) to the clips.

Note: Steps 3, 4, and plate (25) only applies to Groups 1 and 2. For groups 3 and 4 the hardware can be directly mounted to the machine.

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Illustration 5	g03827068

3. Install the clips to the plate (25) .

   1. Install clip (4) to the plate using bolt (35) with hard washers (31) and nut (13) .

   2. Install clip (28) to the plate using bolt (35) with hard washers (31) and nut (13) .

   3. Install clip (27) to the plate using bolt (35) with hard washers (31) and nut (13) .

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Illustration 6	g03827077

4. Install plate (25) to the existing hardware using bolts (36) with hard washers (31). Route jumper harness (24) as shown in Illustration 6 using cable straps (30) to secure the harness to the clips.

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Illustration 7	g03827082

5. Install brackets (3) and (5) to the existing boss using bolt (32) with hard washer (31) .

6. Install cable tie mounts (9) to the brackets using bolts (32) with hard washers (31) .

7. Secure jumper harness (24) to cable mounts (9) using cable straps (8) .

Note: Step 8 applies only to Groups 1 and 2.

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Illustration 8	g03720815

8. Modify the area of the scab plate shown in Illustration 8 so the bolts do not push into the shield.
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   Illustration 9	g03735831
   (A) 117 mm (4.61 inch) (B) 50 mm (1.97 inch) (C) 32.4 mm (1.28 inch) (D) 38.1 mm (1.50 inch)

   1. Drill two holes 38.1 mm (1.5 inch) in diameter.

   2. Use the following measurements and Illustration 9 to drill the holes in the correct locations.
      • 117 mm (4.61 inch) from the top surface

      • 50 mm (2 inch) apart from one another

      • 32.4 mm (1.25 inch) from the side

Note: Step 9 applies only to Groups 1 and 2.

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Illustration 10	g03827085

9. Install plate (26) using bolts (1) with hard washers (6) .

10. Install nitrogen oxide sensor assembly (16) with two bolts (29) and two hard washers (37) .

11. Install bracket assembly (10) using bolt (34) with hard washer (31) .

12. Route jumper harness (24) through clip (11). Install the clip to bracket assembly (10) using bolt (33) with hard washer (31) .

13. Route jumper harness (24) through clip (11). Install the clip to plate (26) using bolt (34) with hard washer (31) .

14. Install bracket (17) to plate (26) using bolt (34) with hard washer (31) .

15. Route jumper harness (24) as shown in Illustration 10. Use cable strap (30) to secure the harness to the clip (17) .

16. Connect to the new NOx sensor location.
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    Illustration 11	g03827086

    1. Install plate assembly (3) using bolt (33) with hard washer (31) on one end. On the other end, route jumper harness (25) through clip (11) and secure to the plate assembly using bolt (33) with hard washer (31) .

    2. Install bracket assembly (2) to the existing boss using bolt (33) with hard washer (31) .

    3. Route jumper harness (25) through clip (11) and use bolt (33) with hard washer (31) to secure the clip to the bracket assembly.

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Illustration 12	g03827106
(39) 380-6885 Heat Shield As (40) 380-6886 Heat Shield As (41) 380-6887 Heat Shield As

17. Remove heat shield assemblies (39), (40), and (41) .

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Illustration 13	g03827122
(42) 349-9673 Exhaust Diffuser Adapter Gp (43) 034-3412 Cable Strap (44) 7N-4080 Boot

18. Remove boot (44) by removing cable strap (43). Remove exhaust diffuser adapter group (42) from the turbocharger.

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Illustration 14	g03827123
(7) 1W-5455 Clamp (21) 444-5130 Diffuser (38) 445-7910 Exhaust Lines Gp

19. Install exhaust lines group (38) that consists of clamp (7) and diffuser (21).

    1. Position the diffuser with the outlet 0° to 5° from the engine vertical (straight down).

    2. Position the clamp fastener pointing out or down.

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Illustration 15	g03827126
(39) 380-6885 Heat Shield As (40) 380-6886 Heat Shield As (41) 380-6887 Heat Shield As

20. Install heat shield assemblies (39), (40), and (41) .

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Illustration 16	g03827127
(12) 343-9010 Bellows As (14) 346-0334 Band Clamp (15) 346-0335 Band Clamp (20) 442-8720 Exhaust Tube As

21. Install flexible exhaust pipe group between the turbocharger and the aftertreatment package.

    1. Ensure that the bellows alignment and protective package is on the bellows assemblies. Pre-assemble the slip joint loosely.

    2. Assemble the joint at the turbocharger outlet and loosely tighten band clamp (14) .

    3. Align and assemble exhaust tube assembly (20) at the aftertreatment inlet ball joint and loosely tighten band clamp (15) .

       Note: The slip joint should slide smoothly with a minimum engagement of 40 mm (1.6 inch). Engagement will be verified when ink line on the slip joint inner tube is no longer visible.

    4. Tighten band clamp (15) to 35 ± 2 N·m (26 ± 2 lb ft).

    5. Tighten band clamp (12) to 35 ± 2 N·m (26 ± 2 lb ft).

    6. Verify the ink mark on the slip joint inner tube is still not visible.

    7. Remove the bellows alignment and protective packaging by cutting the straps on these components.

    8. Tighten the clamp at the slip joint to 55 ± 8 N·m (41 ± 6 lb ft)

Note: The step below is for the installation of the exhaust heat shield assemblies, which only applies to the 836K.

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Illustration 17	g03737096

22. Install the exhaust heat shield assemblies.
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    Illustration 18	g03827132
    (12) 343-9010 Bellows As (14) 346-0334 Band Clamp (15) 346-0335 Band Clamp (18) 442-8716 Heat Shield As (19) 442-8718 Heat Shield As (20) 442-8720 Exhaust Tube As (22) 449-2534 Heat Shield As (23) 449-2535 Heat Shield As

    1. Ensure that the bellows alignment and protective package is on the bellows assemblies. Pre-assemble the slip joint loosely.

    2. Assemble the joint at the turbocharger outlet and loosely tighten band clamp (14) .

    3. Align and assemble exhaust tube assembly (20) at the aftertreatment inlet ball joint and loosely tighten band clamp (15) .

       Note: The slip joint should slide smoothly with a minimum engagement of 40 mm (1.6 inch). Engagement will be verified when ink line on the slip joint inner tube is no longer visible.

    4. Tighten band clamp (15) to 35 ± 2 N·m (26 ± 2 lb ft).

    5. Tighten band clamp (20) to 35 ± 2 N·m (26 ± 2 lb ft).

    6. Verify the ink mark on the slip joint inner tube is still not visible.

    7. Remove the bellows alignment and protective packaging by cutting the straps on these components.

    8. Tighten the clamp at the slip joint to 55 ± 8 N·m (41 ± 6 lb ft)

    9. Install heat shield assembly (23) on the rear of the flex pipe.

    10. Install heat shield assembly (22) on the front of the flex pipe. Secure the springs between heat shield assembly (22) and (23). Secure the springs to the turbocharger wraps also.

    11. Install heat shield assembly (18) on the rear of the flex pipe towards the Clean Emissions Module (CEM). Make sure to insert the heat shield assembly into the CEM wrap.

    12. Install heat shield assembly (19) on the front of the flex pipe towards the CEM.

    13. Secure the springs between heat shield assembly (18) and (19) .