Initial Inspection and Diagnostic Overview: Overview

All internal combustion engines and drivelines produce some noise and vibration; operating in a real world environment adds noise and vibration that are not subject to control. Vibration isolators, mufflers and dampers are used to reduce these to acceptable levels.

A driver who is unfamiliar with a vehicle may think that some sounds are abnormal when actually the sounds are normal for the vehicle type. For example, Traction-Lok (R) differentials will produce a slight chatter noise on slow turns after extended highway driving. This is considered acceptable and has no detrimental effect on the locking axle function.

As a technician, it is very important to be familiar with vehicle features and know how they relate to NVH concerns and their diagnosis. If, for example, the vehicle has automatic overdrive, it is important to test drive in and out of overdrive mode.