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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. |
Before troubleshooting a problem, perform the visual checks. Perform the checks with the engine OFF and with the parking brakes ON. Put the transmission control in NEUTRAL and the transmission rotary selector spool in NEUTRAL. During the checks, use a magnet to separate ferrous particles from nonferrous particles.
Note: Modulating reducing style and ECPC style lock up clutch valves require software with different application codes. Refer to Special Instruction, REHS4541, "Software Configuration Guide{3168, 4800, 4808, 7600, 7610, 7620}".
Problem: The oil level is too high.
Note: The transmission oil must be at operating temperature and the transmission must be run in NEUTRAL to circulate oil in the lines, cooler, and planetary before an accurate oil level reading can be taken.
Probable Cause
- Oil is leaking from the pump drive into the transmission gear pump.
Problem: The oil level is too low.
Note: The transmission oil must be at operating temperature and the transmission must be run in NEUTRAL to circulate oil in the lines, cooler, and planetary before an accurate oil level reading can be taken.
Probable Cause
- Perform "Check: Check for oil leakage.". Add oil before any tests are performed.
Problem: There is an indication of water in the oil.
Probable Cause
- Failure of the transmission oil cooler
Problem: There is an indication of air in the oil.
Probable Cause
- Perform "Check: Check for oil leakage.".
Problem: Rubber particles are found.
Probable Cause
- Seal failure
- Hose failure
Problem: Black coarse material is found.
Probable Cause
- Worn clutches in the transmission
- Failure of a thrust disc
Problem: Black fiber is found.
Probable Cause
- There is a worn lockup clutch in the torque converter. See "Check: Check the suction screens.".
Problem: Thin strands that are elastic are found.
Probable Cause
- Worn clutches in the transmission
Problem: Iron chips or steel chips are found.
Probable Cause
- Broken components in the transfer gears or in the transmission
Problem: Shiny steel particles are found
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| Illustration 1 | g03028758 |
| (1) Transmission section of the gear pump. | |
Probable Cause
- Mechanical failure of the transmission section (1) of the gear pump. See "Check: Check the transmission oil filter.".
Problem: Aluminum particles are found.
Probable Cause
- Worn housings, load pistons, or selector pistons in the pressure control valve
- Mechanical failure of the pump drive. See "Check: Check the suction screens."
Check: Check the oil level in the transmission section of the hydraulic tank.
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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, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates. |
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| Illustration 2 | g03028759 |
| (2) oil level sight gauge for the transmission | |
Check the oil level in the transmission section of the hydraulic tank. Look for air or for water at sight gauge (2). Many problems in the transmission are caused by low oil levels or by air in the oil. If necessary, add oil to the transmission section of the hydraulic tank. In order to determine the correct oil to use, refer to your Operation and Maintenance Manual, SEBU8133.
Inspect all the oil lines, the hoses, and the connections for damage or for leaks. Look for evidence of an oil leak under the machine.
Note: If oil can leak out of a fitting or a connection, air can enter the system. Air in the system can be as harmful as not enough oil.
Check: Check the transmission oil filter.
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| Illustration 3 | g03028736 |
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(3) Transmission oil filter
(4) Bypass valve | |
Remove transmission oil filter (3). Inspect the filter for foreign material.
Note: Transmission oil filter (3) has an oil filter bypass valve (4). Oil filter bypass valve (4) allows oil to bypass the oil filter element whenever the pressure difference between the inlet oil and the outlet oil at the oil filter gets too high. Any oil that does not go through the filter element flows directly into the hydraulic circuit. Unfiltered oil may cause sticking valves and restrictions in valve orifices.
The pressure bypass valve (4) in the transmission oil filter (3) senses the difference in inlet and outlet pressure. The bypass valve (4) is set to open when the differential pressure between inlet and outlet exceeds
Check: Check the suction screens.
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| Illustration 4 | g03028739 |
| (5) Cover for the suction screen | |
Remove the magnetic screen. Inspect the magnetic screen for foreign material and/or for restrictions.
Check: Check the inside of the transmission case.
Drain the oil from the transmission. Separate the transmission case from the torque converter housing. Inspect the bottom of the transmission case for debris and inspect the bottom of the torque converter housing for debris. Inspect the suction screen. Clean the suction screen.