Front end noise that gets louder with acceleration

Tiny
BOSTONBOATSWAIN
  • MEMBER
  • 2008 CHEVROLET COBALT
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Have noise in front end. It gets louder the faster you go. Turn wheel left, noise stays the same. Turn wheel right, noise diminishes (doesn't go away, just changes, gets lower and sounds smoother).

Pretty sure it's the front passenger wheel bearing. Anyway to confirm before I purchase a new one?

Thanks in advance for any help verifying which bearing.

BostonB
Tuesday, November 19th, 2019 AT 8:07 AM

1 Reply

Tiny
CARADIODOC
  • MECHANIC
  • 33,873 POSTS
Most likely you are correct on two counts, but there are tests to confirm this. You are indeed describing a noisy front wheel bearing, but the clue where the noise is reduced when turning to the right only applies to pressed-in wheel bearings. Those are used by Toyota, Ford, and '80s and older Chrysler products. When you change lanes to the right and the noise gets quieter, it is the right bearing that is noisy. That slight change in direction causes some of the vehicle's weight to be transferred off the right bearing, making it momentarily quieter.

This doesn't apply to your bolt-on-style front bearing assembly. It can sound like the noise is coming from the right side, it can get quieter when turning slightly to the right, and still end up being the left one that's noisy. That noise can be transmitted to the other side of the car, making it sound like that's where it's coming from. The good news is if you change the wrong bearing, you can install the old one on the other side of the car.

My preferred method of identifying the noisy bearing is to run the engine, in gear, on a hoist, then listen next to each one with a stethoscope. It will be obvious which one is louder. Another method is to raise the tire off the ground, shift to "neutral", reach over the tire and lightly wrap your fingertips around part of the coil spring, then rotate the wheel / tire slowly, by hand. If that bearing is noisy, you'll feel the vibration in the spring.

There's two points of value to be aware of. The first is while this is a project that can be handled by a competent do-it-yourselfer, the most common mistake has to do with tightening the axle nut. There must never be any vehicle weight on the bearing when that nut is not tightened to specs. Some people will set the tire on the ground to hold the wheel and axle shaft from spinning so they can tighten the nut. By that time it's too late. The damage has already been done. Instead, just stick a punch or screwdriver into a cooling slot in the rotor, then tighten the nut with a click-type torque wrench. The torque spec for your car is 155 foot - pounds, which is quite low compared to other models.

Here's a link to an article that shows how to replace the bearing assembly, if you need it:

https://www.2carpros.com/articles/bearing-hub-replacement

My second point is if your car has anti-lock brakes, you have to buy a bearing assembly with the wheel speed sensor attached. If you do not have anti-lock brakes, compare the prices of that bearing for both applications, with and without anti-lock brakes. Most of the time you're going to find the bearing with the sensor is less-expensive than the same bearing without the sensor. You can use the less-expensive bearing; just don't bother with the electrical connector.
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Tuesday, November 19th, 2019 AT 5:03 PM

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