D8T and D9T Track-Type Tractors Caterpillar

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the power train.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

Probable Causes Of Problems In The Torque Converter

The toque converter is a device that changes the relief of torque to speed between the input and output shafts of the machine. The torque converter is a type of hydrodynamic fluid coupling that transfers rotating power from the engine to a rotating driven load.

Troubleshooting Problem List

• Torque converter pressure is high.

• Torque converter pressure is low.

• The torque converter overheats.

• The stator clutch does not engage.

• The stator clutch does not disengage.

Troubleshooting

Note: Refer to the Powertrain Schematic, UENR4191 for the D9T Track-Type Tractor to identify components that are referenced in the sections that follow.

Use the built-in electrical diagnostics that are performed with the electronic control module (ECM) to determine the service codes for the Transmission ECM and Implement ECM modules.

Note: This machine is equipped with a Transmission ECM and an Implement ECM. The control modules have built-in diagnostics that detect faults in the electronic system.

Torque Converter Pressure Is High

Probable causes:

• There is a restriction inside the torque converter.

• There is a downstream restriction in the power train cooler or brakes and transmission lube passages.

• The torque converter inlet relief valve is stuck in the closed position.

• Power train oil is too cold.

Torque Converter Pressure Is Low

Probable causes:

• The oil level is low.

• There is a restriction in the oil flow circuit or a dirty oil strainer.

• Air leaks on the inlet side of the power train oil pump.

• Power train oil pump failure.

• Leakage inside the transmission.

• Transmission main relief valve is stuck open.

• Torque converter inlet relief valve is stuck in the open position or the seal is cut.

• Seal leakage inside the torque converter is too high.

Torque Converter Overheats

Probable causes:

• The machine is being used for the wrong application. There is too much load.

• Incorrect transmission gear is being used for the load that is on the machine. Shift to a lower gear.

• The power train oil level is incorrectly high or too low.

• The coolant level in the engine radiator is low.

• The oil cooler or oil lines are restricted.

Stator Clutch Does Not Engage

Probable causes:

• The stator clutch valve or solenoid is faulty.

• The torque converter output speed sensor is malfunctioning.

• There is excessive leakage in the stator clutch.

• The stator clutch is damaged.

• Oil flow to the stator clutch valve is restricted.

Stator Clutch Does Not Disengage

Probable causes:

• The stator clutch valve or solenoid is faulty.

• The torque converter output speed sensor is malfunctioning.

• The stator clutch valve solenoid is unplugged or has a bad connection.

• The stator clutch is damaged.

• The stator clutch is not installed or software enabled. Verify the installation parameters in Cat Electronic Technician (CAT ET) Service Tool.