Rework Procedure to Install a New Electronic Control Module (ECM) Bracket on Certain 797 Off-Highway Truck Engines {1901, 1901} Caterpillar

Off-Highway Truck/Tractor

797F (S/N: LAJ1-UP; WSP1-UP)

Introduction

This Special Instruction describes the rework procedure to install a new Electronic Control Module (ECM) bracket on certain 797 Off-Highway Truck Engines.

Note: The C175-20 retrofit engine (serial number prefix Series A4K) is not built from the factory with the series isolation system. The C175-20 retrofit engine is built with the single stage isolation system with the 8T-9655 Isolation Mount.

The vibration profile that the C175-20 retrofit engine is exposed to in a 797 or 797B truck is different than the C175-20 when installed in a 797F truck. The differences in engine mounts and the 797/797B frame contribute to the different vibration profile. If a retrofit serial number ( Series A4K) engine would need to be installed in an 797F truck, the series isolation system would need to be added to the retrofit engine.

Important Safety Information

Do not perform any procedure in this Special Instruction until you have read this Special Instruction and you understand this information. Use only proper tools and observe all precautions that pertain to the use of those tools. Failure to follow these procedures can result in personal injury.

Work safely. Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs.

A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools to perform these functions properly.

Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard.

Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive. Ensure that any tool, procedure, work method, or operating technique you use that is not recommended by Caterpillar is safe.

Ensure that the product will not be damaged or the product will not be made unsafe by the operation, lubrication, maintenance, or repair procedures used.

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Failure to follow all safety guidelines prescribed in this document and by governing authorities and regulatory agencies may result in severe injury or death of personnel or machine damage.

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When removing a major component or attachment, ensure that it is properly blocked or secured before removing mounting hardware. An assembly that is disconnected without proper blocking may shift or fall, resulting in serious injury or death of personnel or machine damage.

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine. To prevent personal injury or death, perform the following: Park the machine on a smooth, level surface. Lower the work tool to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock.

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Personal injury or death can occur from not following the proper procedure or the recommended tooling. To prevent the possibility of injury or death, follow the established procedure using the recommended tooling.

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Do not operate or work on this engine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact any Caterpillar dealer for replacement manuals. Proper care is your responsibility.

Required Parts List

Note: Table 2 contains parts that are used in Step 13.

Removal Procedure

1. Remove the engine ECM and ECM mounting plate.

Installation Procedure

All fasteners should be tightened to standard torque unless noted.

The new series isolation system will install into the same locations that the ECM mounting plate is installed into.

Note: Follow the order of assembly. The spacer blocks are used when installing the series isolation system. The assembly order and spacer blocks ensure that the correct load is carried by each isolator mount. If the procedure is not followed, the force that some of the mounts will be exposed to can cause premature failure.

Note: The 168-2067 Mount As (primary isolation mount) should be inspected, and replaced if worn or damaged at the engine mid-life point.

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Illustration 1	g06145057
Bottom Bracket Assembly (1) 168-2067 Mount As (2) 189-5358 Bolt (3) 243-1277 Hard Washer (4) 479-1499 Bracket As (5) 8T-0106 Bolt (6) 198-4767 Hard Washers (7) 310-2263 Spacer (8) 333-0140 Bracket (9) 096-9986 Bolts

1. Install the bottom bracket assembly (4) to the engine using: bolt (5), washers (6), spacer (7), bracket (8), and two bolts (9).

   Note: Do Not Torque Bolts (5) and (9).There are 2 versions of bracket (4). The previous version shown in Illustration 1 does not have the weld nut attached to the bracket. With this version the ground strap should be attached to bolt (5).

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   Illustration 2	g06145098
   Bottom Bracket Isolation Mount Assembly (1) 168-2067 Mount As (3) 243-1277 Hard Washers (13) 189-5358 Bolt

   Note: Do Not Torque The Bolt (13) At This Time.

2. Install the 479-1493 Bracket As to the bottom 479-1499 Bracket As with two mount assemblies (1) two bolts (13) and four washers (3). The bolts (13) are one time use only. If the mounts are removed, the bolts (13) should be discarded and a new bolt should be installed.

   The mount assemblies (1) should be installed with the primary mount positioned at the top of each bracket, pointing down through the bracket assembly.

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   Illustration 3	g06224275
   168-2067 Mount As Orientation

3. Top and bottom mount should have the primary half installed from the top of each bracket.
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   Illustration 4	g06145070
   Top Bracket Assembly (1) 168-2067 Mount As (2) 189-5358 Bolt (3) 243-1277 Hard Washer (10) 479-1498 Bracket (11) 6V-5844 Bolt (12) 9X-8268 Washer

4. Install the top bracket (10) to the engine using: two bolts (11) and two washers (12).

   Note: Do Not Torque Bolts (11).

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   Illustration 5	g06145078
   Top Bracket Isolation Mount Assembly (1) 168-2067 Mount As (3) 243-1277 Hard Washers (13) 189-5358 Bolts

5. Install the 479-1493 Bracket As to the top 479-1498 Top Bracket with two mount assemblies (1), two bolts (13) and four washers (3).

   Note: Do Not Torque Bolts (13). 189-5358 Bolts are one time use components, if the mounts are removed, the 189-5358 Bolts should be discarded and a new bolt should be installed.

6. Once all brackets and mounts have been installed, but not torqued, torque the 8T-0106 Bolt and 096-9986 Bolt attaching the bottom bracket to the front housing.
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   Illustration 6	g06240608

7. To achieve the correct spacing between the brackets and the correct load is distributed over all four isolation mounts, install spacer blocks between the bottom bracket and the ECM bracket. Also install spacer clocks between the top bracket and ECM bracket.

   Note: The spacer blocks are included in the kit with the 168-2067 Mount As. The tope mount kit part number is 553-1201, the bottom mount kit part number is 553-1202.

   Note: Directions on how to manufacture the spacer blocks can be found at the end of this document.

8. Torque the 168-2067 Mount As bolts connecting the bottom bracket to the ECM bracket to 20 ± 2 N·m (15 ± 1 lb ft). Leave the spacer blocks in place.

9. Torque the isolation 168-2067 Mount As bolts connecting the top bracket to the ECM bracket to 20 ± 2 N·m (15 ± 1 lb ft). Leave the spacer blocks in place.

10. Torque the two 6V-5844 Bolts attaching the top bracket to the front housing. Torque the left side 6V-5844 Bolts first.

11. Remove the spacer blocks from between the top bracket and ECM bracket, and the spacer blocks between the bottom bracket and ECM bracket.
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    Illustration 7	g06206219

12. Install the ECM to the 479-1493 Bracket As using the new 467-5344 Mounts. The ground strap should be installed on the bottom left corner bolt. The other end of the ground strap should be attached to the 479-1499 Bracket As at the weld nut included in the bracket. To install the strap correctly, use one 6V-7673 Bolt, one 5P-8245 Hard Washer, 8X-6418 Ground Strap, and one 198-4767 Hard Washer installed into the weld nut.

    Note: Install the components in the order that is listed in the step.

13. Install the over-mold harness to the 479-1493 Bracket As.

    Note: The parts for the over-mold harness are located in Table 2.

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    Illustration 8	g06145118

14. Possibly the ECM mounting holes may have been damaged by failed ECM mounts. Refer to Illustration 8 which describes acceptable and failed conditions of the ECM holes. If the paint is not worn, the holes do not need to be checked. If there is wear, the inside diameter of the holes should be checked. The ECM mounting holes should not measure more than 20.75 mm on the inside diameter. If the holes measure wider, the ECM should be replaced.

Illustration 9	g06206220

Instructions on Making Spacer Blocks

1. Two spacer blocks should be used to set the correct gaps between the top and bottom bracket and the ECM bracket.

2. The top spacer blocks should be made to a height of 10.85 ± .1 mm. The bottom spacer blocks should be made to a height of 14.2 ± .1 mm.

3. The width and length of the blocks can vary, depending on what materials are available. Make the width of the blocks twice the height, and to make the blocks long enough that to easily remove after inserting into the gaps between the two isolation mounts. Other options are to add a handle to the blocks, or drill a hole though the blocks and thread/tie off string to make removing the blocks easier.

4. The blocks can be made out of metal or hard plastic.

5. As alternative to the spacer blocks is to use four nuts as spacers. The top bracket can use two 1F-7958 Full Nuts to achieve the 10.85 mm (0.43 inch) gap. The bottom bracket can use two 1L-5021 Nuts to achieve the 14.2 mm (0.56 inch) gap.

Illustration 10	g06240608