Excessive engine noises
| Cause | Correction | |
| Drive belt squeal, insufficient tension or abnormally high loading |
 |
Check the tensioner and inspect the drive belt. Make sure water pump, tensioner pulley, fan hub and alternator turn freely. |
 |
||
 |
|
Check the tension of accessory drive belts. Make sure the accessories turn freely. |
| Intake air or exhaust leaks |
|
Refer to Troubleshooting Logic for excessive exhaust smoke. |
 |
||
| Excessive valve lash |
|
Adjust valves. Make sure the push rods are not bent or the rocker levers are not severely worn. |
|
||
| Turbocharger noise |
|
Check turbocharger impeller and turbine wheel for housing contact. |
|
||
| Gear train noise |
|
Visually inspect and measure gear backlash. Replace gears as required. |
|
||
| Power function knock |
|
Check/replace rod and main bearings. |