Symptom Tree t047
| Cause | Correction |
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When troubleshooting engine noise complaints, make sure the engine accessories (air compressor, fan clutch, freon compressor, or hydraulic pump) are not the cause of the noise. Refer to Engine Noise Diagnostic Procedures – General Information at the end of Section TS before using this symptom tree.
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Electronic fault codes active or high counts of inactive fault codes |
Refer to Section TF in the Troubleshooting and Repair Manual, Fuel Systems and Electronics, B5.9G, C8.3G, L10G-III, Bulletin 3666118, for fault code troubleshooting. |
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Drive belt is loose or has high loading |
Check the drive belt tension. Adjust as necessary. Refer to Procedure 008-003. Check the accessory drive belts. Refer to the OEM service manual. |
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Fan is loose, damaged, or not balanced |
Check the fan. Refer to Procedure 008-040. |
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Lubricating oil pressure is below specification |
Check the oil pressure. If the pressure is low, refer to Procedure 007-999. |
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Lubricating oil level is below specification |
Check the oil level. Verify the dipstick calibration and the oil pan capacity. Fill the system to the specified level. Refer to Procedure 007-009 and Procedure 007-025. |
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Lubricating oil is thin or diluted |
Refer to Procedure 007-999. If the oil pressure is low, refer to the Lubricating Oil Pressure Low symptom tree. |
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Coil wire malfunctioning |
Remove wire from engine and use a digital multimeter to measure resistance across the wire. Refer to Procedure 013-012. |
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Ignition coil malfunctioning |
Check the ignition coil. Refer to Procedure 013-012. |
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Spark plug(s) damaged or incorrect gap |
Inspect plug(s). Refer to Procedure 013-016. |
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Air compressor noise is excessive |
Refer to the Air Compressor Noise is Excessive symptom tree. |
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Fan clutch, hydraulic pump, or refrigerant compressor noise is excessive |
Isolate each component and check for noise. Refer to the OEM service manual. |
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Overhead adjustments are not correct |
Measure and adjust the overhead settings. Refer to Procedure 003-004. |
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Air intake or exhaust leaks |
Inspect the air intake and exhaust systems for air leaks. Refer to Procedure 010-024. |
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Air intake or exhaust piping is contacting the chassis or cab |
Inspect the air piping, chassis, and cab for contact points. Refer to the Operation and Maintenance Manual, B5.9G, B5.9LPG, B Gas Plus, and B LPG Plus Engines, Bulletin 3666112. |
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Turbocharger is worn or damaged |
Check the turbocharger for damage. Measure the turbine and compressor wheel clearances. Refer to Procedures 010-033, 010-039, 010-038, and 010-047. |
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Overhead components are damaged |
Inspect the rocker levers, rocker shafts, cam followers or tappets, push rods, and valves for damage or excessive wear. Refer to Procedures 003-008 or 003-004, 004-014 or 004-015, and 002-004. |
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Gear train backlash is excessive or the gear teeth are damaged |
Check the gear backlash and the gear teeth. Refer to Procedures 001-008, 001-033, and 007-031. |
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Vibration damper is damaged |
Inspect the vibration damper. Refer to Procedure 001-051. |
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Flywheel housing is not aligned correctly |
Check the flywheel housing alignment. Refer to Procedure 016-006. |
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Pistons or piston rings are worn, damaged, or not correct |
Check the pistons for correct part numbers. Refer to Control Parts List (CPL), Bulletin 3379133 or 4021327. Check the pistons and rings for wear and damage. Refer to Procedure 016-006. |
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Main bearing or connecting rod bearing noise |
Refer to the Engine Noise Excessive – Main Bearing symptom tree. |
