Engine Noise Excessive
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Symptom |
Possible Cause |
Action |
Reference |
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Engine Noise Excessive |
Drive belt is loose |
Check the drive belt tension, and drive belt auto-tensioner. Replace if necessary. |
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Fan is loose, damaged, or not balanced |
Check the fan. |
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Belt driven components have worn bearings, belts, or misalignment |
Isolate each component and check for noise. |
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Air intake or exhaust leaks |
Inspect the air intake and exhaust systems for air leaks. |
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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. |
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Lubricating oil level is above or below specification |
Check the oil level. Add or drain oil, if necessary. |
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Lubricating oil is thin or diluted |
Check the viscosity of the oil sample. If the lubricating oil is contaminated, refer to the Lubricating Oil Contaminated symptom diagnosis. |
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Lubricating oil pressure is below specification |
Check the oil pressure. If the pressure is low, refer to the Lubricating Oil Pressure Low symptom diagnosis. |
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Vibration damper is damaged |
Inspect the vibration damper. |
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Coolant temperature is above specification |
Refer to the Coolant Temperature Above Normal - Gradual Overheat symptom diagnosis. |
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Drivetrain noise is excessive |
Disconnect the drivetrain. Check for engine noise. |
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Engine mounts are worn, damaged, or not correct |
Check the engine mounts. |
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Cylinder head components are damaged |
Inspect the rocker arms, valves, and hydraulic lash adjuster for damage or excessive wear. |
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Injector(s) are malfunctioning |
Perform CONSULT Cylinder Cut-out Test to determine if the misfire can be isolated to a single injector. Replace the injector(s) as necessary. |
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Torque converter is loose |
Check the torque converter. |
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Flexplate bolts are loose or broken |
Check the flexplate and the bolts. |
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Timing chain component damage |
Check the engine timing chain, slack guides, tension guides, and chain tensioners. |
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Camshaft gear backlash is excessive |
Check the camshaft gear for backlash. |
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Main bearing or connecting rod bearing noise |
Take oil sample. Check for bearing debris in the oil pan. Inspect the main bearings for damage or excessive wear. Inspect the connecting rod bearings. |
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Engine Noise Excessive (continued) |
Turbocharger noise |
Check the turbocharger for damage. Measure the turbine and compressor wheel clearances. Also check the turbocharger linkage connections. |
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Piston or piston rings are worn or damaged. |
Check for air intake system leaks. Check the pistons and piston rings for wear or damage. Analyze the oil and oil filter to locate an area of probable damage. Check compression. |
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Fuel contaminated with Diesel Exhaust Fluid (DEF) |
Verify high quality fuel is being used and that there is no history of DEF in the fuel system. DEF in the fuel system can cause fuel system components to be inoperative over time. |
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