793F Off-Highway Truck Engine Supplement Caterpillar

Removal Procedure

Start By:

1. Remove the modular front end.

2. Remove the gear pump (torque converter and transmission).

3. Remove the pump drive shaft.

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Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact skin. At operating temperature, the engine coolant is hot and under pressure. Steam can cause personal injury. Check the coolant level only after the engine has been stopped and the cooling system pressure cap is cool enough to touch with your bare hand. Remove the cooling system pressure cap slowly to relieve pressure. Cooling system conditioner contains alkali. Avoid contact with the skin and eyes to prevent personal injury.

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In order to prevent possible personal injury, release the air pressure from the air tank before disconnecting any components of the air system.

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Personal injury can result from contact with refrigerant. Contact with refrigerant can cause frost bite. Keep face and hands away to help prevent injury. Protective goggles must always be worn when refrigerant lines are opened, even if the gauges indicate the system is empty of refrigerant. Always use precaution when a fitting is removed. Slowly loosen the fitting. If the system is still under pressure, release it slowly in a well ventilated area. Personal injury or death can result from inhaling refrigerant through a lit cigarette. Inhaling air conditioner refrigerant gas through a lit cigarette or other smoking method or inhaling fumes released from a flame contacting air conditioner refrigerant gas, can cause bodily harm or death. Do not smoke when servicing air conditioners or wherever refrigerant gas may be present. Use a certified recovery and recycling cart to properly remove the refrigerant from the air conditioning system.

1. Recover the air conditioner refrigerant from the air conditioner system. Refer to Service Manual, SENR5664, "Air Conditioning and Heating Systems with R-134a Refrigerant". Refer to Special Publication, NEDG2500, "Air Conditioning Tools" for the correct procedure.

2. Turn the fuel supply to the OFF position.

3. Turn the power disconnect switch to the OFF position.
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   Illustration 1	g06214700
   For Tooling (A)

4. Use Tooling (A) to support front frame assembly (1).
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   Illustration 2	g06388403
   For Tooling (A1)

5. Use Tooling (A1) to support front frame assembly (1). Refer to Tool Operating Manual, NEHS1334, "Lift Stands (150 Ton)" for more information on Tooling (A1).
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   Illustration 3	g02023136

6. Attach a suitable lifting device onto cross tube (2). The weight of cross tube (2) is approximately 118 kg (260 lb).
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   Illustration 4	g02023140
   Right-Hand Side

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   Illustration 5	g02023141
   Left-Hand Side

7. Remove bolts (3) and bolts (4). Remove shims (5).

   Note: Note the location and the quantity of shims (5) for installation purposes. In case shims (5) are lost or damaged during removal procedure or the engine cross tube is replaced with new, refer to "Engine Cross Tube Shimming procedure" section for the correct installation procedure.

8. Remove cross tube (2).
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   Illustration 6	g03505496

9. Disconnect harness assemblies (6). Disconnect hose (7).
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   Illustration 7	g03505497

10. Disconnect hose (8). Remove clamps (9).
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    Illustration 8	g03505499

11. Disconnect hoses (10). Remove tube assemblies (11).

12. Repeat Step 9 through Step 11 for the opposite side.
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    Illustration 9	g03505504

13. Disconnect hose assemblies (12).
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    Illustration 10	g03505506

14. Disconnect hose assemblies (13).
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    Illustration 11	g03505507

15. Remove clamps (14).
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    Illustration 12	g03505509

16. Disconnect hose assemblies (15).
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    Illustration 13	g03505511

17. Disconnect hose assemblies (16).
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    Illustration 14	g03505512

18. Disconnect harness assemblies (17).
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    Illustration 15	g03505513

19. Remove clamps (18). Disconnect bellows (19).
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    Illustration 16	g03505516

20. Disconnect tubes (20).
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    Illustration 17	g03505519

21. Use a suitable lifting device to remove each of tubes (20). The weight of tube (20) is approximately 16 kg (36 lb).
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    Illustration 18	g03505521

22. Disconnect hose assemblies (21) and hose assemblies (22).
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    Illustration 19	g03505523

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    Illustration 20	g03505525

23. Use a suitable lifting device to support drive shaft (23). The weight of drive shaft (23) is approximately 172 kg (380 lb).

24. Remove bolts (24). Use a suitable prybar to retract drive shaft (23). Use Tooling (B) and Tooling (C) to retain the yoke of drive shaft (23).

    Note: Bolts (24) are not reusable. Discard bolts (24).

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    Illustration 21	g02023184
    Front of Engine

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    Illustration 22	g02023217
    Rear of Engine

25. Install Tooling (D).
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    Illustration 23	g02796468

26. Attach Tooling (E) onto Tooling (D).
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    Illustration 24	g03505530

27. Remove bolts (25) and cap (26). Repeat this step for the remaining rear engine mount.
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    Illustration 25	g03505534

28. Remove bolt (27) and washer (28). Disconnect harness assembly (29) and remove the connecting hardware.
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    Illustration 26	g03505537

29. Remove bolt (30) and washer (31). Disconnect ground strap (32).
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    Illustration 27	g03505538

30. Use Tooling (D), Tooling (E), and a suitable lifting device to remove engine and torque converter (33). The weight of engine and torque converter (33) is approximately 12115 kg (26710 lb).

Installation procedure

1. Install the engine and torque converter (33) in the reverse order of removal.

   1. Tighten bolts (25) to a torque of 300 ± 40 N·m (221 ± 30 lb ft).

   2. Use Tooling (F) to align exhaust piping before installing bellows (19).

   3. Tighten bolts (4) and bolts (3) to a torque of 520 ± 70 N·m (384 ± 52 lb ft).

2. Use the following procedure to mate the universal joint onto the yoke of the torque converter.

   Note: Prior to the drive shaft installation, make sure that the torque converter yoke and the transfer gears yoke are in phase with each other.

   1. Mate the key and pilot diameter of the universal joint with the yoke of the torque converter. Use a suitable rubber or wooden hammer to seat the universal joint.

   2. Tighten bolts (24) to a torque of 775 ± 40 N·m (572 ± 30 lb ft) in an alternating (X) pattern.

   3. Tighten bolts (24), again, to a torque of 775 ± 40 N·m (572 ± 30 lb ft) in an alternating (X) pattern to ensure that the correct torque has been achieved.

Engine Cross Tube Shimming procedure

The following procedure is only to be used if the shims that the machine was shipped with have been lost during the removal procedure or the engine cross tube is replaced with new. In these events the following procedure is to be used to determine the proper number and location of the shims used when replacing / installing the Engine Cross Tube.

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Illustration 28	g06214740

1. If the front suspension cylinders are installed, inspect the upper suspension mount, the shaft, and the bearing on both sides of the machine. If the front suspension cylinders are not installed skip to Step 5.

2. Fully collapse both of the front suspension cylinders. Refer to SEHS9411 Special Instructions Manual, "Servicing the Suspension Cylinders for Large Off-Highway Trucks", "Collapse the Front Suspension Cylinders" section for the correct procedure.

   Note: After collapsing the front suspension cylinders, ensure that the outlet charging valves remain open.

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   Illustration 29	g06214700
   For Tooling (A)

3. Use Tooling (A) to lift the front frame assembly (1) until 25.4 mm (1 inch) of chrome is exposed on the front suspension cylinders from the fully collapsed position.
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   Illustration 30	g06388403
   For Tooling (A1)

4. Use Tooling (A1) to lift the front frame assembly (1) until 25.4 mm (1 inch) of chrome is exposed on the front suspension cylinders from the fully collapsed position. Refer to Tool Operating Manual, NEHS1334, "Lift Stands (150 Ton)" for more information on Tooling (A1).
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   Illustration 31	g06214817
   (Y) Right-Hand Side (Z) Left-Hand Side

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   Illustration 32	g06215543

5. Install cross tube (2).

6. If cross tube (2) does not fit, continue to lift the machine until cross tube (2) fits and use zero shims (5).

7. With cross tube flush against Side (Y), begin installing shims (5) at Side (Z). Install shims (5).

   Note: If five or more shims are required, install the first five shims at Side (Z) and the remaining shims at Side (Y). If five or less shims are required, install all shims at Side (Z).

   Note: Do not force shims (5) into the gap between cross tube (2) and the frame. Only use enough shims (5) to fill the gap.

   Note: Document shim number and location for future reference.

   Note: The total number of shims (5) should not exceed ten for the following models.

   793 - 10 shims maximum

   795 - 10 shims maximum

   797 - 10 shims maximum

   Note: The total number of shims (5) should not exceed eight for the following models.

   785 - 8 shims maximum

   789 - 8 shims maximum

8. Once the shims are fitted, Install all the cross tube mounting bolts.

9. Tighten the cross tube mounting bolts in the cross pattern to a torque of 520 ± 70 N·m (384 ± 52 lb ft).

10. Lower the machine so that the front suspension cylinders are fully collapsed.

11. Charge the front suspension cylinders with oil and nitrogen. Refer to , SEHS9411 Special Instruction Manual , "Servicing the Suspension Cylinders for Large Off-Highway Trucks".