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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause 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. |
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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, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
Before you start the test procedure, complete the following procedure:
- Machine Preparation for Troubleshooting
ReferenceFor more information on preparing the machine for troubleshooting, refer to the Service Manual module for Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.
- Perform visual checks first when you are troubleshooting a problem. Before you make these checks, shift the transmission direction control switch to the NEUTRAL position and engage the parking brake. Stop the engine. During these checks, use a magnet to separate ferrous particles (iron) from nonferrous particles (O-ring seals, aluminum, bronze, etc), if necessary.
- If the machine will not move, check the transmission fuse. The fuse is located at the right rear of the engine compartment.
- Check the oil level in the front differential and the rear differential.
- Check the transmission oil level. Look for air bubbles in the oil or water in the oil. Many problems in the transmission are caused by low oil level or by air in the oil. Add oil to the transmission, if necessary. Refer to Operation and Maintenance Manual, "Lubricant Viscosities and Refill Capacities" for the recommended oil grade and the recommended oil viscosity.
- Air bubbles may be caused by a fitting that is loose or damaged. A loose fitting or damaged fitting allows air to enter the suction side of the system and oil is also allowed to leak. Also, if the transmission oil level is too high and the gears are agitating the oil in the sump, air bubbles may result.
- A leaking transmission oil cooler may cause coolant to enter the system. Water may enter the system if the filler cap or the dipstick is not properly installed.
- Check all oil lines, all hoses, and all connections for damage and for leaks. Look for oil on the ground under the machine.
Note: If oil can leak out of a fitting or out of a connection, air can leak into the system. Air in the system is as harmful as having too little oil.
- Remove the drain plug in the bottom of the transmission case in order to drain the oil from the transmission. Remove the suction screen and clean the suction screen. Inspect the oil and the suction screen for foreign material. Remove the transmission oil filter and inspect the filter for foreign material. (Cut the filter open, if necessary.)
Note: There is an oil filter bypass valve on the inlet side of the transmission oil filter. Whenever the pressure difference between the inlet oil and the outlet oil is more than 345 kPa (50 psi), the bypass valve will open and oil will be allowed to bypass the oil filter element. Any oil that does not flow through the oil filter element flows directly into the hydraulic control circuit. This dirty oil can cause valves to become stuck and valve orifices could become restricted.
- Rubber particles indicate a seal failure or a hose failure.
- Shiny steel particles indicate a mechanical failure or gear wear of the transmission or of a pump.
- A thick accumulation of fibrous material indicates worn clutch discs in the transmission.
- Aluminum particles indicate torque converter wear, a torque converter failure, a worn control valve body, worn selector spools, or a worn load piston in the transmission control valve.
- Iron particles or steel particles indicate broken components in the transmission.
Note: If any of these particles are found during any visual check, all components of the transmission hydraulic system must be cleaned. Do not use any damaged parts. Any damaged parts must be removed and new parts must be installed.
- The drive shafts and universal joints must rotate freely unless cold oil is causing a resistance. If the drive shafts do not turn freely, disconnect the drive shafts and check that the transmission will turn.