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, four-wheel drive vehicles and vehicles with Traction-Lok(R) differentials produce noise when driven on hard surfaces that does not result on two-wheel drive vehicles or on surfaces where wheel slip can occur.

As a technician, it is very important to be familiar with vehicle features and know how they relate to Noise, Vibration and Harshness (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.