Symptom Tree t047
| Cause | Correction |
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When troubleshooting for the cause of engine noise, make sure that the engine accessories (air compressor, fan clutch, freon compressor, or hydraulic pump) are not causing the noise. Refer to Engine Noise Diagnostic Procedures — General Information at the end of this section before using this symptom tree.
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Lubricating oil pressure is below specification |
Check the oil pressure. If the pressure is low, refer to Procedure 007-028. |
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Lubricating oil level is above or below specification |
Check the oil level. Add or drain oil if necessary. Refer to Procedures 007-009 and 007-025. Check the dipstick calibration. |
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Coolant temperature is above specification |
Refer to the Coolant Temperature is Above Normal – Sudden Overheat or the Coolant Temperature is Above Normal – Gradual Overheat symptom tree. |
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Lubricating oil is thin or diluted |
Refer to Section F. If the oil pressure is low, refer to the Lubricating Oil Pressure Low symptom tree. |
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Fan drive belt is loose, tight, or not in alignment |
Check the fan drive belt. Refer to Procedure 008-002. |
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Fan is loose, damaged, or not balanced |
Check the fan. Refer to Procedure 008-040. |
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Engine mounts are worn, damaged, or not correct |
Check the engine mounts. Refer to Procedure 016-002. |
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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 OEM service manual. |
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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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Turbocharger noise |
Refer to the Engine Noise Excessive – Turbocharger symptom tree. |
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Overhead adjustments are not correct |
Adjust the overhead settings. Refer to Procedure 003-004. |
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Injector is malfunctioning |
Perform the single-cylinder cutout test. Replace the injectors as necessary. Refer to Procedures 006-005 and 006-026. |
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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 002-004, 003-009, 004-001, and 004-014. |
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Accessory drive is worn (axial end play is out of specification) |
Check the accessory drive axial end play. Inspect the shaft for wear. Refer to Procedure 009-001. |
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Static injection timing is not correct |
Check the static injection timing. Refer to Procedure 006-025. |
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Vibration damper is damaged |
Inspect the vibration damper. Refer to Procedure 001-052. |
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Air compressor noise is excessive |
Refer to the Engine Noise Excessive – Air Compressor 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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Drivetrain noise is excessive |
Disconnect the drivetrain. Check for engine noise. Refer to the OEM service manual. |
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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 001-013 and 008-018. |
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Main bearing or connecting rod bearing noise |
Refer to the Engine Noise Excessive – Main Bearing symptom tree. |
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Flywheel or flexplate capscrews are loose or broken |
Check the flywheel or flexplate and the mounting capscrews. Refer to Procedure 016-005. |
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Piston, piston rings, or cylinder liner is worn or damaged |
Refer to the Engine Noise Excessive – Piston symptom tree. |
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Rear engine power take-off (REPTO) noise is excessive |
Disassemble and repair the REPTO as necessary. Refer to Procedure 016-007 and the Shop Manual M11 Engine, Bulletin 3666075. |
