There's two ways to verify which bearing is noisy. One is to run the engine in gear, with the vehicle on a hoist, then listen next to each bearing with a stethoscope. One will leave you wondering if it is bad, but you'll definitely know it when you listen to the noisy one. Don't be fooled by the noise changing when turning slightly, as in when changing lanes, and when the noise sounds like it is coming from a specific side of the vehicle. Sound transmits easily and a bad left bearing can sound like the noise is coming from the right side.
The second way to find this is to raise the front tires off the ground, reach over the top of the tire and wrap your fingertips lightly around the coil spring. Rotate the tire by hand and if that bearing is noisy, you'll feel the vibration in your fingertips.
When replacing these bolt-on style bearings, (and the pressed-in style too), it is critical that no vehicle weight be placed on the bearing when the axle nut is not tightened to specs. Some people set the vehicle down onto the tire so it will hold it from spinning when they torque the axle nut. Doing so instantly made the new bearing noisy, and is the reason some people experience repeat failures. Instead, stick a punch or screwdriver into a cooling slot in the rotor. That will hold it from spinning while the axle nut is tightened.
Always use a click-type torque wrench when tightening the axle nuts. The most common specs are in the area of 180 foot-pounds, but a lot of GM vehicles call for as much as 240 foot-pounds.
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Monday, November 26th, 2018 AT 7:39 PM