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Personal injury or death can result from sudden machine movement. Sudden movement of the machine or release of air pressure or oil pressure can cause injury to persons on or near the machine. To help prevent possible injury before testing and adjusting any air system or hydraulic system, perform the procedure in the Testing and Adjusting, "General Information" section. |
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Perform the visual checks before you troubleshoot a problem. Make sure that the transmission is in neutral and stop the engine. During the visual checks, use a magnet to separate ferrous particles (iron and steel) from nonferrous particles (aluminum, rubber and paper).
Check: Check the oil level in the hydraulic tank.
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| Illustration 1 | g00634778 |
(1) Brake oil cooler | |
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| Illustration 2 | g00634789 |
(2) Torque converter, pulled unit and brake oil cooler | |
Check the oil level in the hydraulic tank. Look for air or water in the sight gauge. Many problems in the torque converter are caused by low oil level or air in the oil. Add oil to the hydraulic tank, if necessary. See the Operation and Maintenance Manual for the correct type of oil.
Problem: There is an indication of water in the oil
Probable Cause
- Failure of brake oil cooler (1)
- Failure of torque converter, pulled unit and brake oil cooler (2)
Problem: There is an indication of air in the oil
Probable Cause
- There is a leakage in the oil lines. See "Check for oil leakage".
Problem: The oil level is too low
Probable Cause
- There is a leakage in the oil lines. See "Check for oil leakage". Add oil before you perform any tests.
- Brake cooling oil can leak into the final drive. Check the oil level in each final drive.
Problem: The oil level is too high
Probable Cause
- The engine crankshaft rear seal is allowing engine oil into the torque converter housing.
Check: Check for oil leakage.
Inspect all oil lines, all hoses and all connections for damage or for leaks. Look for oil on the ground under the machine.
Note: If oil can leak out of a fitting or out of a connection, air can enter the system. Air in the system can be as harmful as having too little oil.
Check: Check the parking brake release oil filter.
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| Illustration 3 | g00634850 |
(3) Parking brake release oil filter | |
Remove parking brake release oil filter (3). Inspect parking brake release oil filter (3) for foreign material. Cut the filter open, if necessary.
Problem: Rubber particles are found
Probable Cause
- Seal failure
- Hose failure
Problem: Shiny steel particles are found
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| Illustration 4 | g00634879 |
Pump for torque converter charging, scavenge, and pakring brake release. (4) Parking brake release pump section (5) Torque converter charging pump section (6) Torque converter scavenge pump section | |
Probable Cause
- Mechanical failure of parking brake release pump section (4) .
Check: Check the torque converter charging oil filter.
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| Illustration 5 | g00634900 |
(7) Torque converter charging oil filter | |
Remove torque converter charging oil filter (7). Inspect torque converter charging oil filter (7) for foreign material. Cut the filter open, if necessary.
Note: Torque converter charging oil filter (7) has an oil bypass valve. The bypass valve allows the oil to bypass the oil filter element or the screen whenever the pressure difference between the inlet oil and the outlet oil becomes too high. Any oil that does not flow through the filter element or through the screen goes directly into the hydraulic circuit. Dirty oil can cause sticking valves and restrictions in valve orifices.
The pressure setting of the bypass valve in torque converter charging oil filter (7) is 140 kPa (20 psi).
Problem: Rubber particles are found
Probable Cause
- Seal failure
- Hose failure
Problem: Shiny steel particles are found
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| Illustration 6 | g00634879 |
Pump for torque converter charging, scavenge, and parking brake release . (4) Parking brake release pump section (5) Torque converter charging pump section (6) Torque converter scavenge pump section | |
Probable Cause
- Mechanical failure of the torque converter charging pump section (5)
Check: Check the torque converter scavenge screen.
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| Illustration 7 | g00634905 |
(8) Cover for the torque converter scavenge screen | |
Make sure that the oil has been drained from the hydraulic oil tank and from the torque converter for the next check.
| NOTICE |
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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
Remove cover (8) for the torque converter scavenge screen. Inspect the torque converter scavenge screen for foreign material or restrictions.
Problem: Rubber particles are found
Probable Cause
- Seal failure
- Hose failure
Problem: Shiny steel particles are found
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| Illustration 8 | g00634879 |
Pump for torque converter charging, scavenge, and parking brake release. (4) Parking brake release pump section (5) Torque converter charging pump section (6) Torque converter scavenge pump section | |
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| Illustration 9 | g00634912 |
(9) Pump drive (10) Pulled unit pump | |
Probable Cause
- Mechanical breakdown of the oil pump drive (9) .
- Mechanical failure of the parking brake release pump section (4). See "Check the parking brake release oil filter".
- Mechanical failure of the torque converter charging pump section (5). See "Check the torque converter charging oil filter".
Problem: Aluminum particles are found
Probable Cause
- Mechanical failure of the torque converter
Problem: Black fiber is found
Probable Cause
- Worn lockup clutch in the torque converter
Check: Check the screen for the brake oil cooler.
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| Illustration 10 | g00634958 |
(11) Screen for the brake oil cooler | |
Remove screen (11) for the brake oil cooler. Inspect screen (11) .
Problem: Rubber particles are found
Probable Cause
- Seal failure
- Hose failure
Problem: Shiny steel particles are found
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| Illustration 11 | g00634912 |
(9) Pump drive (10) Pulled unit pump | |
Probable Cause
- There is a mechanical failure of pulled unit pump (10) .
Check: Check the screen for the torque converter, pulled unit and brake oil cooler.
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| Illustration 12 | g00634956 |
(12) Screen for the torque converter, pulled unit and brake oil cooler | |
Remove screen (12) for the torque converter, pulled unit and brake oil cooler. Inspect screen (12) .
Problem: Rubber particles are found
Probable Cause
- Seal failure
- Hose failure
Problem: Shiny steel particles are found
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| Illustration 13 | g00634879 |
Pump for torque converter charging, scavenge, and parking brake release. (4) Parking brake release pump section (5) Torque converter charging pump section (6) Torque converter scavenge pump section | |
Probable Cause
- There is a mechanical failure of torque converter charging pump section (5). See "Check the torque converter charging oil filter".
Problem: Large quantities of aluminum particles are found
Probable Cause
- Mechanical failure of the torque converter
Problem: Black fiber is found
Probable Cause
- Worn lockup clutch in the torque converter
Check: Check the inside of the hydraulic tank (torque converter, pulled unit, and brake section).
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| Illustration 14 | g00635050 |
(13) Suction screen for pulled unit pump (14) Suction screen for the torque converter charging pump section and for the parking brake release pump section | |
Drain the oil from the hydraulic tank. Remove the outer cover from the hydraulic tank. Inspect the bottom of the hydraulic tank for debris. Remove the hoses from the back of the hydraulic tank in order to remove suction screens (13) and (14). Inspect the suction screens. Clean the suction screens.
| NOTICE |
|---|
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
Problem: Rubber particles are found
Probable Cause
- Seal failure
- Hose failure
Problem: Shiny steel particles are found
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| Illustration 15 | g00634879 |
Pump for torque converter charging, scavenge, and parking brake release. (4) Parking brake release pump section (5) Torque converter charging pump section (6) Torque converter scavenge pump section | |
Probable Cause
- Mechanical failure of parking brake release pump section (4). See "Check the parking brake release oil filter".
- Mechanical failure of the torque converter charging pump section (5). See "Check the torque converter charging oil filter". Also, see "Check the screen for the torque converter, pulled unit and brake oil cooler".
- Mechanical failure of the torque converter scavenge pump section (6)
Problem: Aluminum particles are found
Probable Cause
- Mechanical failure of the torque converter. See "Check the torque converter scavenge screen".
Problem: A large quantity of aluminum particles are found
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| Illustration 16 | g00634912 |
(9) Pump drive (10) Pulled unit pump | |
Note: A small amount of aluminum particles is normal.
Probable Cause
- Mechanical failure of the pump drive (9). See "Check the torque converter scavenge screen".
- Mechanical failure of the pulled unit pump (10). See "Check the screen for the brake oil cooler".
Problem: Black fiber is found.
Probable Cause
- Failure of the wheel brakes
- There is a worn lockup clutch in the torque converter. See "Check the torque converter scavenge screen". Also, see "Check the screen for the torque converter, pulled unit and brake oil cooler".
Problem: Shiny steel particles and/or chrome particles are found
Probable Cause
- There is a mechanical failure of a hydraulic cylinder and/or of a cylinder rod. Inspect the cylinder rods for scoring.
Note: If any of the above particles are found during any visual checks, all components of the hydraulic system and of the brake cooling system must be cleaned. Do not use any damaged parts. Damaged parts must be replaced with new parts.