SUPPORT-STEP 3958823 - Caterpillar

Probable Causes
Oil cooler core is plugged or air flow over the core is low.
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.Recommended Actions
Note: Care must be taken in order 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.Oil Cooler Core Is Plugged Or Air Flow Over The Core Is Low
Check for restrictions in the core of the oil cooler. Air flow that is generated from the fan travels through the cooler fins in order to carry the heat away from the oil. High temperature can be caused by blockage of the fins of the cooler core. Ensure that the fins of the cooler core are clean. Ensure that the fins of the cooler core are not restricted. Check and clean any buildup of debris from the exterior of the cooler core, the fan, and/or the fan shroud. Clean the oil cooler core or repair the oil cooler core.Periodically clean the cooling fins of the hydraulic oil cooler core. Material from the operating environment (such as wood chips, debris from landfills, or coal dust) can easily clog the fins.Use a bent copper tube that is approximately 1/4 to 3/8 inch diameter as an extension to the air nozzle. This adaptation will facilitate cleaning of the middle spaces. Blow out the core with compressed air. Move the air nozzle in a systematic pattern so that the air flow covers the whole core that includes areas in the corner. Clean the middle space between the hydraulic oil cooler and the radiator cores.Do not use steam or high-pressure water for frequent cleaning . Debris may be held deep in the cores. Use steam or high-pressure water in this case. Ensure that the cleaning is thorough. Partial removal or total removal of the hydraulic oil cooler may be required for better access.Incomplete cleaning with water may cause remaining debris to harden in place. Use lights and wire probes in order to ensure that the cleaning is thorough and complete.If the debris has hardened in the center of the cores, remove these cores for cleaning. 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 cores 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. The hydraulic oil cooler is prevented from sufficiently cooling the oil. If the fins on the hydraulic oil cooler are clogged