69D and 769D Off-Highway Truck/Tractors and 771D Quarry Truck Power Train Caterpillar

Note: Make sure that the filters and the screens are clean before you test any pressures. Make sure that the oil is at operating temperature before you perform this test.

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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.

Illustration 1	g00525844
(1) Torque converter outlet relief valve (A) Pressure tap for torque converter outlet pressure

This test will show the following conditions if the conditions exist:

• The torque converter operates correctly.

• Torque converter outlet relief valve (1) is correctly set.

Procedure

1. Connect the Electronic Technician (ET) to the machine. Use ET to measure the engine rpm.

   Note: The 9U-7400 Multitach or the Electronic Control Analyzer Programmer (ECAP) can be used instead of ET.

2. At pressure tap (A), connect a hose to the nipple. Connect a 8T-0854 Pressure Gauge (1000 kPa (145 psi)) to the hose.

3. Start the engine. Run the engine at the low idle rpm in NEUTRAL.

4. The drive wheels must not turn during a stall test. Be certain that the air pressure is at the normal pressure for operation. Engage the parking brakes and the service brakes.

   Note: If the brakes do not keep the machine from moving, put the machine against a solid object that will not move.

5. Be certain that the oil is at 82° to 138°C (180° to 250°F).

6. Move the transmission control to the FIRST position.

   Note: Make sure that the body is lowered to the frame before performing the remainder of the procedure.

7. Slowly increase the engine rpm to the maximum governor setting. The machine will try to move.

8. The engine rpm must be 1908 ± 65 rpm with the torque converter in a stall condition.

9. The pressure on the gauge must be 414 ± 34 kPa (60 ± 5 psi).

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NOTICE
Do not keep the torque converter in a stall condition for long periods of time. Damage could occur in the torque converter, the engine, and the brakes.

10. When this test is complete, put the transmission control in NEUTRAL. Stop the engine. Remove the test equipment.

Problem: The engine speeds are out of specification.

Probable Cause

• Refer to the engine system Troubleshooting, SENR1062, "P-312 Can Not Reach Top Engine RPM" for problems that involve the engine.

• The torque converter failed.

Problem: The high idle rpm is correct, but the stall speed is too high and the torque converter outlet pressure is correct.

Probable Cause

• The torque converter failed.

• The engine has too much power.

Problem: The torque converter outlet pressure is too low, and the oil gets too hot during normal operation.

Probable Cause

Perform the test in the Testing and Adjusting, "Relief Valve (Torque Converter Inlet) Pressure - Test and Adjust".

Problem: The torque converter outlet pressure is too low.

Illustration 2	g00287213
(1) Outlet relief valve (2) Spacers

Probable Cause

• Perform the test in the Testing and Adjusting, "Relief Valve (Torque Converter Inlet) Pressure - Test and Adjust".

• The torque converter outlet relief valve is set too low. Add spacers (2). Refer to Table 2.

Problem: The torque converter outlet pressure is too high, and the oil temperature is not too hot.

Probable Cause

The setting of torque converter outlet relief valve (1) is too high. Remove spacers (2). Refer to Table 2.

Problem: The torque converter outlet pressure is correct, and the oil gets too hot during normal operation.

Probable Cause

The power train oil cooler is not operating properly.