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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. |
Use this procedure to troubleshoot high hydraulic oil temperature or use this procedure if one of the following event codes is active.
| Event Codes | ||
|---|---|---|
| Code and Description | Conditions which Generate this Code | System Response |
| E878(2) High Hydraulic Oil Temperature | System temperature exceeds |
Modify machine operation to reduce system load. Check hydraulic oil level. Check the hydraulic oil cooling system. |
| E878(3) High Hydraulic Oil Temperature | System temperature exceeds |
Immediate safe shutdown required. |
- Separate circuit water temperature is too high.
- Oil cooler core is plugged.
- Thermal bypass valve and/or cooler efficiency
- The hydraulic oil cooler leaks.
- Viscosity of the oil is wrong.
- Oil contamination
- The hydraulic oil contains a large amount of air.
- System pressure is low.
- Oil level is low.
Note: Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the machine. You must be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component that contains fluid. Dispose of all fluids according to local regulations.
Separate Circuit Water Temperature Is Too High.
The cooler is an oil-to-water type cooler. Water temperature entering the cooler should be less than
The cooler is an oil-to-water type cooler. Check for restrictions in the core of the oil cooler side. Check for restrictions in the core of the water/coolant side. Coolant flow that is generated from the water pump travels through the cooler to carry the heat away from the oil. High temperature can be caused by blockage of the passages of the cooler core. Ensure that the passages of the cooler core are clean are not restricted. Check and clean any buildup of debris from the exterior of the cooler core. Clean the oil cooler core or repair the oil cooler core.
Do not use steam or high-pressure water for frequent cleaning. If steam or high-pressure water is required to dislodge any debris that is held deep in the cores, ensure that the cleaning is thorough. This condition may require partial removal or total removal of the hydraulic oil cooler for better access. Incomplete cleaning with water may cause remaining debris to harden in place.
If you use a degreaser and steam for removal of oil and grease, wash the core with detergent and hot water. Thoroughly rinse the core with clean water. Dry the core completely before operating the machine in the work mode.
Thermal Bypass Valve And/Or Cooler Efficiency
Check the thermal bypass valve and/or cooler efficiency. If the thermal bypass valve of the hydraulic oil cooler is stuck in the OPEN position, the oil is not being directed through the cooling tubes. This condition prevents the hydraulic oil cooler from sufficiently cooling the oil.
With an infrared thermometer, test the temperature of the cooler inlet and the cooler outlet. A temperature differential of at least
Note: If replacing the bypass valve does not correct the problem, the cooler core may be clogged with contaminants. This condition may be present after a catastrophic failure of a hydraulic pump, motor, or other hydraulic component that would release particles and contaminants into the system. The cooler core must be cleaned or the cooler core must be replaced.
Perform this inspection before cleaning the core.
Inspect the hydraulic oil cooler for leaks. Thoroughly examine all surfaces, tubes, and connections on the hydraulic oil cooler for signs of leaks. If oil is leaking, dirt and dust will adhere to the oily surfaces more than dry surfaces. Tighten any loose connections or fittings that might be leaking and recheck for leaks. The hydraulic oil cooler should be replaced if there are leaks on surfaces in addition to the fittings.
Ensure that oil is the correct viscosity for the operating conditions. To determine the correct oil viscosity, refer to the Operation and Maintenance Manual, SEBU8200, "Lubricant Viscosities and Refill Capacities" for your machine.
Ensure that the hydraulic oil is not contaminated.
Oil contamination may cause undesirable characteristics in hydraulic component operation due to the contaminants that cause changes to the oil viscosity.
Oil that is contaminated with dirt or other foreign particles can clog orifices and small passages. Contaminants may also cause moving parts such as valve spools to stick. Contaminants may damage the surfaces of mating parts that move against each other such as the valve spool and spool bore.
Oil that is contaminated with water will become cloudy and the viscosity will decrease. Over time the contamination will cause the oil to have an odor. Oil contaminated with water is also more spongy. This condition may cause a lag in cylinder movement and soft operation of components. An oil sample and subsequent oil analysis can determine if the oil is contaminated and the type of contaminants that are in the oil.
The Hydraulic Oil Contains A Large Amount Of Air
Ensure that the hydraulic oil is not aerated.
- Check all the fittings and connections for proper torque on the suction side of pumps or on negative pressure side of other motors and other components.
- Check the fluid level sight gauge on the side of the hydraulic oil tank. If the hydraulic oil appears cloudy, check inside the hydraulic oil tank to ensure that the suction tube and the return oil tube are both in place and that both are submerged in the oil (return oil splashing or spraying back into the tank can aerate oil)
- Examine implement cylinder rod seals for signs of oil leakage or seepage which may allow air to be drawn in when the rod end of the cylinder is below tank/ambient pressure (such as during blade FLOAT)
- Loosen oil line connections after each hydraulic component (pressure side) and examine the oil for aeration at each inspection point. If the oil appears aerated as the oil seeps out of the loosened connection, that component may be the source of the aeration. The aeration may also occur some place between that component and the prior component that showed no signs of aeration
- Examine the suction hose, the main suction manifold, and all suction lines, fittings, and connections from the suction manifold to the steering pump, the fan pump, and the implement pump. Look for indications of oil leakage. If oil leaks from these lines or connections when the machine is shut down, the connections will also draw air into the hydraulic oil system during operation. This condition will cause the pumps to infuse the air and distribute it to the components in that system/circuit and then return the aerated oil back to the tank
- Ensure that the procedure to purge the air from the hydraulic system was completed correctly.
Oil aeration may be caused by several factors such as low oil levels in the tank, cavitation in pumps or cylinders, worn pump components (shaft seals, port plates, pump housing seals), or leaks in the system on the suction side of pumps. Air in the oil can make the oil more spongy, causing a lag in cylinder movement. Air in the oil can cause erratic operation of hydraulic components.
Examine the hydraulic oil for signs of oil aeration. Aerated oil can appear cloudy if the air is finely spread in the oil. An oil sample and subsequent oil analysis can determine if the oil is aerated or if the oil is contaminated. If oil aeration is found, the source of the aeration must be located and eliminated.
Repair or replace any suspect components and then retest for the symptom.
Check the system pressure. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" in this manual.
Check the oil level. Add oil, if necessary. Refer to Operation and Maintenance Manual, SEBU8200, "Hydraulic System Oil Level - Check".