D6T XE Electrical & Hydraulic Troubleshooting Hydraulic Fan Does Not Shut Off Caterpillar


Hydraulic Fan Does Not Shut Off
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1.1. Probable Causes
2.1. Recommended Actions
3.2. Fan Blades And/Or Spider May Be Damaged
4.2. Air - To - Air - After - Cooler (Ataac) Intake Air Flow Restriction
5.2. Cooler Cores Are Not Operating Efficiently
6.2. Engine Fan Control Solenoid Not Operating Properly
7.2. Fan Pump Discharge Pressure Sensor Or Any Of The Temperature Sensors Involved In The Fan Control Strategy Are Not Providing Accurate Data
8.2. Pump Control Valve Is Not Operating Properly
9.2. Fan Pump Is Not Operating Properly

------ WARNING! ------

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.


Probable Causes

  • Fan blades and/or spider may be damaged

  • Air-to-air-after-cooler (ATAAC) intake air flow restriction

  • Cooler cores are not operating efficiently

  • Fan control solenoid may be bad

  • Fan pump discharge pressure sensor or any of the temperature sensors involved in the fan control strategy are not providing accurate data

  • Pump control valve is not operating properly

  • Fan pump is not operating properly

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.

Fan Blades And/Or Spider May Be Damaged

Damage to the fan blades can negatively affect the efficiency of the fan, reducing the volume of air they move. Erosion of the leading edges or the tips of the fan blade can also reduce the efficiency of the fan.

If blade wear, or erosion occurs, the engine ECM will try to compensate for the inefficiencies by speeding up the fan. At the extreme, the fan cannot rotate fast enough to make up the difference. This condition may cause overheating and make the fan sound like it is running faster than necessary. Inspect each of the eight fan blades for damage, especially the leading edges. If the edges are bent or damaged, or if the blade is bent or flattened out, replace the fan assembly.

Inspect the spider for damage. If the spider is bent or twisted, replace the fan assembly.

Air - To - Air - After - Cooler (Ataac) Intake Air Flow Restriction

Normal intake manifold air pressure with high intake air and/or exhaust temperature can be caused by blockage of the fins of the ATAAC core. Ensure that the fins of the ATAAC core are clean and are not restricted. Check and clean any buildup of debris from the exterior of the ATAAC core, the fan, and/or the fan shroud. Clean and repair as necessary.

Clean the cooling fins of the ATAAC periodically. Clean the cooling fins more frequently if the operating environment includes contamination and debris that can easily clog the fins (such as wood chips, landfill debris, coal dust). Externally flush the ATAAC core with water, in order to remove dirt and foreign objects. If possible, flush the fins from the front side, which is the opposite direction of normal air flow through the fins. Blow dry the assembly in the reverse direction of normal air flow and ensure the ATAAC core is clean.

Cleaning the ATAAC core is essential if a restriction is found or oil contamination and debris are present after a turbo failure. Remove the ATAAC core. Internally flush the ATAAC core with a solvent that removes oil and other foreign substances. Shake the core in order to eliminate any trapped debris. Wash the aftercooler with hot, soapy water. Thoroughly rinse with clean water and blow dry the aftercooler with compressed air. Blow dry the assembly in the reverse direction of normal air flow and ensure the whole system is clean. The entire air Inlet system must be cleaned, including the replacement of the air filters.

Normal intake manifold air pressure with high intake air and/or exhaust temperature can also be caused by a restriction of intake air flow through the intake air system, including the ATAAC core. Inspect the engine air cleaner inlet and associated ducting in order to ensure that intake air passages are not blocked or collapsed. Check for dirt tracks on the clean side of the engine air cleaner element, the air inlet hose, and the clamps. If dirt tracks are observed, contaminants are flowing past the engine air cleaner element, the seal for the air cleaner, and/or the air inlet hose.

Inspect the engine air cleaner element. Replace a dirty engine air cleaner element with a clean engine air cleaner element.

Check the air ducts between the air cleaner canister and the ATAAC inlet and also check the air ducts between the ATAAC outlet and the intake manifold for blockages or crimps that may restrict air flow.

Check the air ducts between the air cleaner canister and the ATAAC inlet and also check the air ducts between the ATAAC outlet and the intake manifold for air leaks that may reduce the air flow to the intake manifold.

Cooler Cores Are Not Operating Efficiently

The cores must not be clogged externally or internally. Air flow from the hydraulic demand fan through the cooler fins carries heat away from the oil. If any of the cooler cores are not operating efficiently, the fan cannot properly cool the air, oil, or engine coolant. High temperature can be caused by blockage of the fins of the cooler core. Ensure that the ATAAC core, the radiator cores, and the hydraulic oil cooler core (and bypass valve) are clean and not restricted. Check and clean any buildup of debris from the exterior of the cooler core, the fan, and/or the fan shroud. Clean and repair as necessary.

Clean the cooling fins of the hydraulic oil cooler core periodically. Clean the cooling fins more frequently if the operating environment includes contamination and debris that can easily clog the fins (such as wood chips, landfill debris, coal dust, etc.).

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 AMOCS radiator cores. Use a bent copper tube that is approximately 1/4 -3/8 inch diameter as an extension to the air nozzle. This will facilitate cleaning of the middle spaces. Use lights and wire probes in order to ensure that the cleaning is thorough and complete.

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 may require partial removal or total removal of the hydraulic oil cooler in order to gain better access. Incomplete cleaning with water may cause remaining debris to harden in place. If the debris has hardened in the center of the cores, these cores may need to be removed for thorough 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.

Engine Fan Control Solenoid Not Operating Properly

With AVSpare Electronic Technician (Cat ET), test the circuit in order to determine if the engine fan control solenoid operating properly.

Refer to Troubleshooting, RENR9312, "Cooling Fan Control - Test".

Fan Pump Discharge Pressure Sensor Or Any Of The Temperature Sensors Involved In The Fan Control Strategy Are Not Providing Accurate Data

If the fan pump discharge pressure sensor or any of the temperature sensors involved in the fan control strategy are not providing accurate data to the engine ECM, the fan cannot operate properly. If the fan cannot be adjusted properly, all of the electrical devices in the fan system should be checked to ensure that they are operating properly. Using a pressure gauge, test the fan pump pressure (at the test port) and then compare that to the system status display for the fan pump pressure sensor in the display in order to determine if the sensor is sending correct data the engine ECM for fan operation. With an infrared temperature gauge, check the temperatures of the hydraulic oil, the coolant (at the point of the sensor), and the intake air (at the inlet tube on the manifold) to determine if the sensors are sending correct data the engine ECM for fan operation. Replace any defective sensors or correct wire harness problem (if present) to correct the problem. If the fan returns to normal operation after these step, troubleshooting is complete.

Pump Control Valve Is Not Operating Properly

If any of the component parts of the pump control valve are damaged, or if contamination is causing spools to stick in the valve body bores, the fan cannot operate properly. Remove and disassemble the fan pump control valve. Inspect all spools, spool bores, springs, orifices, and passages to determine if there is any damage to these components or if contamination is causing a spool to stick. Clean, repair, and/or replace as necessary. If the fan returns to normal operation after these procedures, troubleshooting is complete.

Fan Pump Is Not Operating Properly

If the fan pump is worn and cannot provide sufficient oil flow for operating the fan under all temperature requirements, the fan pump may need to be rebuilt or replaced. Perform a pump flow test to determine if the fan pump is capable of providing enough oil flow to properly operate the fan through all temperature ranges.

Note: Disconnecting the solenoid should cause the pump to go to high pressure cutoff and the fan should turn faster than the target fan RPM.

Replace the fan pump if wear or damage to the pump is such that the pump cannot provide sufficient oil flow under all conditions. If the fan returns to normal operation after this procedure, troubleshooting is complete.

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