A relatively high-pitched noise is whining in the passenger compartment, increasing in volume with increases in engine rpm, when the vehicle is running at high speeds or under a heavy load.
1.Main causes
Mechanical noise from the engine
Combustion noise
Fan noise
Exhaust noise
Vibrations transmitted through air, engine mounts, hoses, and cables
2.Mechanics of noise development
The following illustration shows the route through which the noises and vibrations enter the passenger compartment.