1. Visual Inspection:
* Look for Leaks: Check around each wheel bearing for grease leaks. This is a sign of a damaged seal, often preceding a complete bearing failure. Look for grease on the hub, around the axle, or on the brake caliper.
* Check for Play: Jack up the car safely, secure it on jack stands, and then grab each wheel at the 3 and 9 o'clock positions. Try to wiggle or move the wheel up and down, and side to side. Excessive play (movement) indicates a potentially bad bearing. Be careful not to confuse slight play (normal) with excessive play. Compare the amount of play between wheels to help determine if one is significantly worse than the others. Ideally, there should be minimal to no play.
2. Sound Check:
* Listen for Noise: With the car jacked up and the engine off, rotate each wheel by hand. Listen carefully for any growling, humming, grinding, or rumbling sounds. These are classic symptoms of a failing wheel bearing. A bad bearing will often make more noise at higher speeds (when the wheel is rotating faster).
* Road Test: Drive the car at various speeds, listening carefully for unusual noises. A bad bearing might make more noise at higher speeds, and the noise might change pitch or intensity as you turn the steering wheel. Pay close attention to the sound's location. Does it seem to be coming from the front or rear? From the left or right side?
3. Advanced Checks (Require Tools):
* Play Check with a Wrench: While the car is jacked up, you can use a wrench to try and more firmly check for play. This can be more sensitive to subtle play than just your hand.
* Bearing Temperature Check: After a short drive, carefully feel the hubs of each wheel. A significantly hotter hub than others can indicate a bearing issue, as friction generates heat. *Caution: Be extremely careful; the brakes and other components can be extremely hot!*
Important Considerations:
* Front vs. Rear: Wheel bearing failure is more common in the front wheels due to higher loads and turning forces.
* Similarity of Sounds: Other components can produce similar noises, making diagnosis tricky. A worn CV joint, for example, can sound similar to a bad wheel bearing.
* Professional Diagnosis: If you're unsure, it's always best to take your car to a qualified mechanic for a professional diagnosis. Improper diagnosis and repair can lead to further damage and safety risks.
Do not drive the car if you suspect a bad wheel bearing. A completely failed bearing can cause loss of control and lead to an accident. Get it checked as soon as possible.
