ISM, ISMe, and QSM11 – Engine Noise Excessive

Air intake or exhaust leaks

Inspect the air intake and exhaust systems for air leaks. Refer to Procedure 010-024 in Section 10.

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 Procedures 007-009 and
007-025 in Section 7.

Lubricating oil pressure is below specification

Check the oil pressure. Refer to Procedure 007-028 in Section 7. If the pressure is low, refer to the Lubricating Oil Pressure Low symptom tree.

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.

Lubricating oil is thin or diluted

Refer to Procedure 007-999 in Section F. If the oil pressure is low, refer to the Lubricating Oil Pressure Low symptom tree.

Fan drive belt is loose, tight, or not in alignment

Check the fan drive belt. Refer to Procedure 008-002 in Section 8.

Fan is loose, damaged, or not balanced

Check the fan. Refer to Procedure 008-040 in Section 8.

Engine mounts are worn, damaged, loose, or not correct

Verify the condition of the mounts. Refer to the OEM service manual.

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.

Turbocharger noise

Refer to the Engine Noise Excessive – Turbocharger symptom tree.

Overhead adjustments are not correct

Measure and adjust the overhead settings. Refer to Procedure 003-004 in Section 3.

Overhead components are damaged

Inspect the rocker levers, rocker shafts, cam followers, tappets, push rods, and valves for damage or excessive wear. Refer to Procedure 003-009 in Section 3, and
Procedures 004-001,
004-014 in Section 4, or
Procedure 002-004 in Section 2.

Injector is malfunctioning

Perform the single-cylinder cutout test. Replace the injectors as necessary. Refer to Procedure 006-005 in Section 6.

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 in Section 9.

Vibration damper is damaged

Inspect the vibration damper. Refer to Procedure 001-052 in Section 1.

Air compressor noise is excessive

Refer to the Air Compressor Noise Excessive – Air Compressor symptom tree.

Fan clutch, hydraulic pump, or refrigerant compressor noise is excessive

Isolate each component and check for noise. Refer to the OEM service manual.

Drivetrain noise is excessive

Disconnect the drivetrain. Check for engine noise. Refer to the OEM service manual.

Gear train backlash is excessive or the gear teeth are damaged

Check the gear backlash and the gear teeth. Refer to Procedures 001-036,
001-039, and
001-040 in Section 1.

Main bearing or connecting rod bearing noise

Refer to the Engine Noise Excessive – Main Bearing symptom tree.

Flywheel or flexplate capscrews are loose or broken

Check the flywheel or flexplate and the mounting capscrews. Refer to Procedure 016-005 in Section 16.

Static injection timing is not correct

Check the static injection timing. Refer to Procedure 006-025 in Section 6.

Piston, piston rings, or cylinder liner is worn or damaged

Refer to Engine Noise Excessive – Piston symptom tree.

Rear engine power take-off (REPTO) noise is excessive

Disassemble and repair the REPTO as necessary. Refer to Procedure 016-007 in Section 16.