2010 Toyota Vitz Bearings

Noisy wheel bearings are very common. Noisy differential bearings are very uncommon, and you won't hear them because there's no vehicle weight on them like there is on the wheel bearings.

You bought a part for your mechanic to install? That's like bringing your own food to a restaurant.

There's two ways to find the noisy bearing. One is to raise the front wheels off the ground, reach over the top and wrap your fingertips around the coil spring, then feel for the vibration when you rotate the wheel. My preferred method is to run the car in gear on a hoist, then listen next to each bearing with a stethoscope. One will sound a bit rumbly, but then the noisy one will be obviously much louder.

You can also use a tool called the "Chassis Ear". That's a set of six microphones, a switch box, and head phones. You place the microphones near suspect parts, then drive around while listening to each one. By moving the microphones around, you can zero in on the source of the noise.