824H Wheel Dozer, 825H Soil Compactor and 826H Landfill Compactor Power Train Caterpillar

The torque converter stall test helps determine if the engine is producing the correct power output. This stall test is used in many diagnostic procedures.

The service brakes must be applied when the tests are performed. Make sure that the service brakes are fully operational before you perform any tests.

Make sure that the transmission oil is at the normal operating temperature of 75° to 105°C (167° to 220°F) when any tests are performed.

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Personal injury or death can result from machine movement. When tests and adjustments are made to the transmission or the torque converter, the parking brake must be disengaged. To prevent movement of the machine and personal injury perform the procedure that follows.

1. Move the machine to a smooth horizontal location.

2. Engage the parking brake and shift the transmission to the NEUTRAL position.

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Illustration 1	g00819655
Electro-hydraulic Control Valve

3. Set the hydraulic fan to the maximum rpm. In order to run the hydraulic fan system at the maximum rpm, the connection to the electro-hydraulic control valve for the hydraulic fan system must be disconnected.

   Note: The electro-hydraulic control valve is located on the right side of the engine and below the hydraulic fan pump. Turn the key start switch to the OFF position. Disconnect the electrical connection from the connection (1) on the electro-hydraulic control valve.

4. Start the engine. Warm the transmission oil to normal operating temperature of approximately 75° to 105°C (167° to 220°F).

   Reference: For more information about preparing a machine for troubleshooting, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting".

5. Ensure that the work tool is positioned on the ground.

6. Fully depress the right side service brake pedal. Shift the transmission direction control and speed control to the SECOND SPEED FORWARD position. Hold the brake pedal in the depressed position for the duration of the test. Release the parking brake.

   Note: Do not use the left brake pedal. If the left brake pedal is used, place the transmission neutralizer override switch in the OFF position.

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Illustration 2	g00819722
Caterpillar Monitoring System (2) Speedometer/Tachometer module (3) Gauge display (4) Display for the monitoring system

7. Fully depress the governor control pedal. Allow the engine rpm to stabilize. Then, observe the tachometer. The correct torque converter stall speed is 1952 ± 65 rpm.

8. Shift the transmission direction control and speed control to the NEUTRAL position.

   Note: Allow the engine coolant and the transmission oil to cool. Wait at least two minutes between tests in order to allow the transmission oil to cool.

   If the torque converter stall speed is too high, the engine power output could be too high or the torque converter could have excess slippage.

9. If the torque converter stall speed is too low, the engine may not be developing full power. There may be a parasitic load on the engine.