Testing And Adjusting

Usage:

Introduction

When the words "use again" are in the description, the specification given can be used to determine if a part can be used again. If the part is equal to or within the specification given, use the part again.

When the word "permissible" is in the description, the specification given is the "maximum or minimum" tolerance permitted before adjustment, repair and/or new parts are needed.

A comparison can be made between the measurements of a worn part and the specifications of a new part to find the amount of wear. A part that is worn can be used again if an estimate of the remainder of its service life is good. If a short service life is expected, replace the part.

Troubleshooting The Transmission Hydraulic System

Make reference to the following warning and pressure tap locations for all checks and tests of the transmission hydraulic system. If the problem area is not known, do the checks and tests in the order they are given. For all tests, the oil must be at normal temperature of operation.

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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, do the procedure that follows before testing and adjusting the transmission.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel.

2. Put the transmission forward/reverse shuttle control in the NEUTRAL position.

3. Activate the neutral lockout switch. Stop the engine.

4. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.

5. Activate the parking brakes.

6. Lower the buckets or implements (loader and backhoe) and stabilizers to the ground.

7. Make sure all hydraulic pressure is released before any fitting, hose or component is loosened, tightened, removed or adjusted.

Troubleshooting can be difficult. A list of possible problems and corrections is on the pages that follow.

This list of problems and corrections will only give an indication of where a problem can be and what repairs are needed. Normally, more or other repair work is needed beyond the recommendations on the list. Remember that a problem is not necessarily caused only by one part, but by the relation of one part with other parts. This list cannot give all possible problems and corrections. The serviceman must find the problem and its source, then make the necessary repairs.

Always make visual checks first. Check the operation of the machine and then check with instruments.

Two-Wheel Drive

Transmission Hydraulic System In Neutral (Engine Running)
(1) Oil filter with bypass. (2) System relief valve. (3) Transmission solenoid (forward/reverse) control valve. (4) Torque converter. (5) Inlet relief valve for torque converter. (6) Oil cooler. (7) Transmission lubrication system. (8) Oil (sump) reservoir. (9) Suction screen. (10) Oil pump [gerotor]. (11) Relief valve [cold start]. (A) Pressure tap for pump. (B) Reverse clutch pack. (C) Pressure tap for reverse clutch. (D) Pressure tap for forward clutch. (E) Forward clutch pack. (F) Pressure tap for torque converter inlet. (G) Pressure tap for torque converter outlet. (H) Pressure tap for lubrication and cooling. (AA) Activated components in system. (BB) Tank oil. (CC) Converter inlet oil. (DD) Pump oil. (EE) Return oil from converter outlet. (FF) Lubrication oil.

All-Wheel Drive

Transmission Hydraulic System In Neutral (Engine Running)
(1) Oil filter with bypass. (2) System relief valve. (3) Transmission solenoid (forward/reverse) control valve. (4) Torque converter. (5) Inlet relief valve for torque converter. (6) Oil cooler. (7) Transmission lubrication system. (8) Oil (sump) reservoir. (9) Suction screen. (10) Oil pump [gerotor]. (11) Relief valve [cold start]. (12) All-wheel drive solenoid. (A) Pressure tap for pump. (B) Reverse clutch pack. (C) Pressure tap for reverse clutch. (D) Pressure tap for forward clutch. (E) Forward clutch pack. (F) Pressure tap for torque converter inlet. (G) Pressure tap for torque converter outlet. (H) Pressure tap for lubrication and cooling. (J) All-wheel drive clutch pack. (K) Pressure tap for All-wheel drive clutch pack. (AA) Activated components in system. (BB) Tank oil. (CC) Converter inlet oil. (DD) Pump oil. (EE) Return oil from converter outlet. (FF) Lubrication oil.

Location Of Pressure Taps

(A) Pressure tap for pump. (F) Pressure tap for torque converter inlet.

(H) Pressure tap for lubrication and cooling.

(G) Torque converter outlet pressure tap location.

(K) All-wheel drive clutch pressure tap location.

Visual Checks

For all tests, the engine must be running at LOW idle and the oil must be at normal operating temperature.

During these checks, use a magnet to separate ferrous particles from nonferrous particles.

1. Check the oil level in the transmission. Look for air (bubbles) or water on the dipstick. Many problems in the transmission are caused by low oil level or air in the oil. Add oil to the transmission if it is needed.

a. Air (bubbles) is usually caused by a loose tube or damaged casting that allows air to enter the suction side of the system along with allowing oil to leak out.

2. Check all oil lines, hoses and connections for leaks and damage. Look for oil on the ground under the machine.

3. Move the levers for the speed control and the direction control to REVERSE and FORWARD and all SPEED positions. The detents must be felt in each speed position. The direction control actuation must give the same positive activation to the hydraulic control circuit for clutch engagement in both directions.

NOTE: There is an oil filter bypass valve on the inlet side of the transmission oil filter. The oil filter bypass valve will open and let oil bypass the oil filter element whenever the pressure difference between inlet oil and outlet oil through the oil filter gets above 138 ± 14 kPa (20 ± 2 psi). Any oil that does not go through the filter element goes directly into the hydraulic circuit. Dirty oil can cause a restriction in valve orifices and cause valves to stick.

4. Drain the oil from the transmission case by removing the oil plug and then remove the cover plate from lower right side of the transmission for further draining of any remaining oil. After removal of the plate on the lower right side of the transmission case, remove and inspect the suction screen and the bottom of the transmission case for debris. Remove and inspect the transmission oil filter for foreign material.

a. Rubber particles indicate seal or hose failure.

b. Shiny steel particles indicate mechanical failure or gear wear of the transmission or pump.

c. A heavy accumulation of black fiber material indicate worn clutch discs.

d. Aluminum particles indicate a failure of a clutch piston or torque converter.

e. Iron or steel chips indicate broken components in the transmission.

Operational Checks

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Make reference to WARNING on the first page of the section Troubleshooting The Transmission Hydraulic System.

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NOTICE

Any unusual noises during this check should be noted. Loud noises could indicate that repairs are needed.

1. Start the engine.

2. Lower the stabilizers and lift the rear wheels about 150.0 mm (6.0 in.) off the ground.

3. Place the bucket hydraulic controls in the bucket lowering position and lift the front wheels about 150.0 mm (6.0 in.) off the ground.

4. The engine speed is to be at LOW idle.

5. With the engine running and brakes on, move the lever for the forward/reverse shuttle and the lever for the transmission speeds.

6. Operate the machine in each direction and in all speeds. Make note of noises that are not normal and find their source. If the operation is not correct, make reference to the Check List During Operation for "problems" and "probable causes".

Problem: Transmission does not operate in any speed or does not engage (slips) in all speeds.

Probable Cause:

1. Neutral lockout switch engaged.

2. Low oil pressure caused by:

a. Low oil level.

b. Failure of oil pump (10).

c. Air leaks on inlet side of the pump.

d. Leakage inside transmission.

3. Mechanical failure in transmission.

a. Clutch discs and plates have too much wear.

b. Leakage at the seals.

4. Electrical failure in shift control unit or defective transmission control fuse.

Problem: Transmission does not shift.

Probable Cause:

1. Air leaks on inlet side of pump (10).

2. Wiring to transmission solenoid control valve not connected or broken.

3. Electrical failure in shift control unit or defective transmission control fuse.

4. Low oil pressure - see Oil Pressure Too Low, Probable Cause.

Problem: Transmission gets hot.

Probable Cause:

1. Bad temperature gauge.

2. High oil level.

3. Core of oil cooler not completely open.

4. Too much slipping in the clutch.

a. Low oil pressure - see Oil Pressure Too Low, Probable Cause.

b. Damaged clutch.

5. Low oil flow as a result of pump wear or extra leakage in the hydraulic system.

6. Wrong application for vehicle. Too much torque converter slippage caused by too much load.

7. Air in the oil. Air leaks on intake side of pump (10).

8. Low oil flow through torque converter (4), caused by torque converter relief valve (5) being stuck open.

9. Wrong oil in transmission.

Problem: Pump noise not normal.

Probable Cause:

1. A loud sound at short time periods gives an indication that foreign material is in the transmission hydraulic system.

2. A constant loud noise is an indication of pump failure.

3. Failed or damaged suction tube.

Problem: Noise in the transmission which is not normal.

Probable Cause:

1. Parts have wear or damage.

Problem: Transmission operates in forward speeds only.

Probable Cause:

1. Wiring to transmission solenoid control valve not connected or broken.

2. Shift control unit malfunctioning or defective solenoid.

3. Discs and plates have too much wear in reverse direction clutches.

4. Leakage at seal rings.

5. Reverse clutch components have damage.

6. Control valve gasket has damage.

7. Forward clutch warped.

Problem: Transmission operates in reverse speeds only.

Probable Cause:

1. Wiring to transmission solenoid control valve not connected or broken.

2. Shift control unit malfunctioning or defective solenoid.

3. Discs and plates have too much wear in forward direction clutches.

4. Leakage at the seal rings.

5. Forward clutch components have damage.

6. Control valve gasket has damage.

7. Reverse clutch warped.

Problem: Clutch engagement is slow and makes rough shifts.

Probable Cause:

1. Low transmission oil pressure - see Oil Pressure Too Low, Probable Cause.

2. Internal (inner) oil leaks.

3. Sticking solenoids.

Problem 1: Oil pressure too low.

Probable Cause:

a. Low oil level.

b. Failure of transmission oil pump.

c. Suction leak.

d. Wrong oil in transmission.

Troubleshooting Methods

Electrical Testing

Electrical connections between harnesses may not be tight. This can cause electrical problems, either permanent or intermittent (come and go). Ensure that the connections at the all-wheel drive solenoid and the all-wheel drive switch are tight before other tests are made.

6V-7070 Digital Multimeter

Use the 6V-7070 Digital Multimeter or equivalent for making continuity checks, resistance measurements or voltage measurements. The optional 8T-3224 Needle Tip Group for the 6V-7070, is useful during troubleshooting. For instruction on use of the 6V-7070, see Special Instruction SEHS7734.

NOTE: Except for harness tests, continuity testers (such as 8T-0500), or voltage testers (such as 5P-7277) are not recommended for use on present-day Caterpillar electrical circuits.

Transmission Hydraulic System Tests

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Make reference to WARNING on the first page of the section Troubleshooting The Transmission Hydraulic System.

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NOTICE

For all tests, the machine must be at operating temperature.

Required removal of components prior to testing of transmission system.

1. Remove four screws (1) from two plates (2), one plate per side of the cab.

2. Remove mat (3) from cab. Remove five screws (4) from plate (5). Set plate (5) aside.

3. Remove four screws (6) and set floor plate (7) aside.

4. Proceed to the appropriate test required. When testing is completed re-install the plates, screws, and mat to the cab.

Test 1.

Transmission Oil Pump Pressure

This test will show if:.

a. Transmission oil pump is good.

Procedure:

1. At pressure tap (A), use a coupler and connect a pressure gauge [4000 kPa (600 psi)] to the nipple.

2. Place the forward/reverse shuttle in NEUTRAL, also place the speed shift lever in NEUTRAL.

3. With the parking brake activated, start and run the engine at LOW IDLE rpm.

4. Shift the forward/reverse shuttle to FORWARD and with the speed shift lever in NEUTRAL, run the engine at HIGH IDLE rpm. The pressure on the gauge must be 1450 ± 100 kPa (210 ± 15 psi).

5. When this test is complete, reduce engine speed to LOW IDLE, place forward/reverse shuttle in NEUTRAL, stop engine and remove the test equipment.

Test 2.

Torque Converter Outlet Pressure

This test will show if:

a. Engine performance is good.

b. Torque converter operates correctly.

c. There is oil flow through oil cooler.

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NOTICE

Any unusual noises during this check should be noted. Loud noises could indicate that repairs are needed.

1. Start the engine.

2. Lower the stabilizers and lift the rear wheels about 150.0 mm (6.0 in.) off the ground.

3. Place the bucket hydraulic controls in the bucket lowering position and lift the front wheels about 150.0 mm (6.0 in.) off the ground.

4. The engine speed is to be at LOW idle during these previous steps.

5. Stop the engine, and proceed with the following procedure.

Procedure:

1. Install the 6V-3121 Multitach Group on the engine. The 6V-3121 Multitach Group can measure engine rpm by the use of the photo pickup and reflective tape. Special Instruction Form No. SEHS7807 has instructions for its use.

2. At location (G), remove plug and seal and install pressure tap nipple.

3. Connect a pressure gauge [700 kPa (100 psi)] to the nipple assembly.

4. With the transmission shift lever in NEUTRAL position, start and run the engine at LOW IDLE rpm. Ensure that HIGH IDLE rpm and LOW IDLE rpm are correct according to the specifications in the book titled "3054 Engine for Caterpillar Built Machines", Form SENR5815.

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NOTICE

To make sure that the transmission oil does not get hot, do not hold the transmission in a stall condition for more than ten seconds. After the transmission is stalled, put the controls in NEUTRAL and run the engine at 1200 to 1500 rpm to cool the oil.

5. With engine running at HIGH IDLE rpm, brakes fully engaged and the transmission at normal operating temperature [59 to 71°C (138 to 160°F)], shift to FOURTH SPEED position. Shift forward/reverse shuttle to FORWARD and stall the torque converter until converter temperature reaches 90 to 93°C (194 to 200°F). With these conditions, stall rpm should be as per Stall RPM Chart.

6. When the test is complete, put the forward/reverse shuttle in NEUTRAL and the shift lever in NEUTRAL. Stop the engine and remove test equipment.

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NOTICE

Do not keep the torque converter in a stall condition for very long periods of time. This will cause the torque converter, engine and brakes to get hot.

Problem 1: Torque converter outlet pressure is too low.

Probable Cause:

a. Torque converter inlet relief valve (5) is open.

b. Weak or bad pump.

c. Check type of fuel.

d. Engine problem.

e. Leakage in torque converter.

Problem 2: The oil gets too hot during normal operation.

Probable Cause:

a. Not enough oil in torque converter (4) because torque converter inlet relief valve (5) is open.

b. Failure in oil pump (10).

c. Failure in torque converter (4).

d. Bad temperature gauge. Replace temperature gauge and the sending unit.

e. Debris blocking air flow to oil cooler and/or engine cooler.

Problem 3: Torque converter outlet pressure is too high.

Probable Cause:

a. Too much restriction in oil cooler (6), or oil cooler lines.

Problem 4: High idle is correct [Step 4], but stall speed (rpm) [in Step 5] is too high. Torque converter outlet pressure is correct.

Probable Cause:

a. Bad torque converter (4).

Problem 4: Stall speed (rpm) is low, but torque converter outlet pressure is correct.

a. Engine problem.

Test 3.

Forward and Reverse Clutch Pressure and Transmission Lubrication

This test will show if:

a. Oil pressure to the forward and reverse clutch is good.

b. Oil pressure to the transmission lubrication circuit is good.

Procedure:

1. Install the 6V-3121 Multitach Group on the engine. The 6V-3121 Multitach Group can measure engine speed (rpm) by the use of the photo pickup and reflective tape. Special Instruction Form No. SEHS7807 has intructions for it use.

2. At pressure taps (C), (D) and (H) connect a hose group to the nipple assemblies.

(H) Pressure tap for lubrication and cooling.

3. At pressure tap (C) and (D) connect a pressure gauge [4000 kPa (580 psi)] to the hose group.

4. At pressure tap (H) connect a pressure gauge [400 kPa (60 psi)] to the hose group.

5. Start and run the engine at LOW IDLE speed.

6. With the transmission gear shift lever in NEUTRAL, shift the forward/reverse shuttle to FORWARD. The pressure on the forward clutch gauge must be 1410 ± 100 kPa (205 ± 15 psi). The lubrication gauge must be 170 ± 70 kPa (25 ± 10 psi). The reverse clutch gauge must be 0 kPa (0 psi).

7. Now shift the forward/reverse shuttle to REVERSE, transmission gear shift lever in NEUTRAL. The reverse clutch pressure shall be within ± 25 kPa (± 3.5 psi) of that in FORWARD, at the same engine speed. The lubrication gauge must be 170 ± 70 kPa (25 ± 10 psi). The forward clutch gauge must be 0 kPa (0 psi).

8. When the test is complete, put the forward/reverse shuttle in NEUTRAL, engage the parking brakes and stop the engine. Remove test equipment.

Problem 1: Both forward and reverse clutch pressure too low.

Probable Cause:

a. System relief valve spring weak.

b. Oil level low.

c. Oil filter (1) is plugged. Replace dirty oil filter.

d. Oil pump (10) failure.

e. Neutralizer button on gear shift lever or tilt control lever shorted causing transmission control solenoid valve to de-energize.

f. Clutch piston seals bad.

Problem 2: Either forward or reverse clutch pressure too low.

Probable Cause:

a. Faulty solenoid.

b. Clutch piston seals bad.

c. Faulty or missing seals on input shaft.

Transmission Shift Blockout Adjustment

(1) Gear shift lever.

1. Place shift lever (1) into first or second gear.

(2) 9S-4191 plug and 3J-1907 seal. (A) Torque converter housing. (B) Transmission housing.

2. Remove and discard 9S-4191 plug (2), and 3J-1907 seal.

Transmission Shift Blockout Adjustment.
(3) Lockout plug. (4) Lockwire. (5) Lockout washer. (6) Seal.

3. Apply sealant to thread of lockout plug (3).

4. Assemble lockout washer (5) and seal (6) to lockout plug (3).

5. Install assembled components to transmission housing (B).

6. Check for free movement of the shift lever into third gear.

7. Seal the head of the lockout plug (3) to lockout washer (5) with 4.0 dm (16.0 in) of lockwire (4).

Troubleshooting The All-Wheel Drive System

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To prevent possible injury, do the procedure that follows before testing and adjusting the differential, rear axle and brakes:

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel. Stop the backhoe loader engine.

2. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.

3. Activate the parking brakes. Lower the buckets or implements (loader and backhoe) and stabilizers to the ground.

Visual Checks

Before any operational checks are made to the all-wheel drive, visually inspect all components.

1. Check the electrical connections.

2. Check for oil leaks around the all-wheel drive solenoid and front drive output shaft, the differential and the wheel planetary assemblies.

Operational Checks

An operational check can be made to quickly see if the all-wheel drive is functional.

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NOTICE

Any unusual noises during this check should be noted. Loud noises could indicate that repairs are needed.

1. Start the engine.

2. Lower the stabilizers and lift the rear wheels about 150.0 mm (6.0 in.) off the ground.

3. Place the bucket hydraulic controls in the bucket lowering position and lift the front wheels about 150.0 mm (6.0 in.) off the ground.

4. The engine speed is to be at LOW idle.

5. Shift the directional control lever to the FORWARD position.

6. Shift the transmission to first speed and note if a rear wheel or wheels rotate.

7. Activate the all-wheel drive switch and note if a front wheel or wheels rotate. If the front wheel or wheels rotate, the all-wheel drive is operational. If there is no front wheel rotation, troubleshoot the system.

8. If the wheels do not rotate, check for the obvious reasons.

a. Malfunctioning electrical connections.

b. Broken axle shaft.

c. Damaged or broken transfer driveshaft.

d. All-wheel drive solenoid is malfunctioning, or is defective.

9. If the wheels do not disengage, check for possibility of:

a. Electrical problem.

b. Warped or damaged clutch

c. All-wheel drive solenoid is malfunctioning, or is defective.

Troubleshooting Methods

Electrical Testing

6V-7070 Digital Multimeter

NOTE: Except for harness tests, continuity testers (such as 8T-0500), or voltage testers (such as 5P-7277) are not recommended for use on present-day Caterpillar electrical circuits.

Pressure Testing

The transmission case contains a clutch pack for all-wheel drive engagement. The pressure needed for proper clutch engagement is 1410 ± 100 kPa (205 ± 15 psi).

Test Procedure

1. Remove plug (K) from transmission and install a test nipple.

2. Install a 0 to 4000 kPa (0 to 600 psi) gauge and long hose.

3. Start the engine and run at high idle speed.

4. At normal operating temperature and with the gear shift selector in the NEUTRAL position, place the direction control lever in the FORWARD position.

5. Activate the all-wheel drive solenoid.

6. Read pressure at the pressure gauge. If the oil pressure is not 1410 ± 100 kPa (205 ± 15 psi), refer to the Transmission Hydraulic System Tests.