Wheel Bearing Problems:
* Noise: The most common symptom is a humming, growling, or rumbling noise that increases with speed. The noise often changes pitch or intensity depending on turns. It will usually be more noticeable at higher speeds and when turning in the direction of the bad bearing.
* Vibration: You might feel a vibration in the steering wheel or floorboard, particularly at higher speeds. This vibration is often more pronounced than with a CV axle issue.
* Play/Wobble: With a severely damaged bearing, you might feel play or wobble in the wheel when you try to move it up and down or side to side. This is a significant indicator.
* Roughness: You might feel a roughness or grinding sensation, especially during turning.
CV Axle Problems:
* Noise: CV axles often make a clicking, popping, or clunking noise, especially when turning, accelerating from a stop, or decelerating. The noise is often more intermittent than a wheel bearing's constant hum. It's often heard at lower speeds than a wheel bearing noise, and can be more localized to the area of the axle.
* Vibration: Vibration can also occur with a bad CV axle, but it's typically less pronounced and more of a shaking or shuddering feeling than the vibration from a wheel bearing.
* Boot Damage: Check the rubber boot surrounding the CV joint (the part that looks like a bellows). Tears or damage to the boot are a strong indicator of a failing CV axle, as it allows grease to leak out and dirt to get in.
* Shaking/Shuddering: Sometimes a bad CV axle will cause noticeable shaking or shuddering, particularly when accelerating or turning.
How to Tell the Difference:
The key difference lies in the *type* of noise and when it occurs:
* Constant hum/growl increasing with speed, especially noticeable during turns = likely wheel bearing.
* Clicking, popping, clunking, especially during turns and acceleration/deceleration = likely CV axle.
Diagnostic Steps:
1. Visual Inspection: Check the CV axle boots for tears or damage.
2. Listen Carefully: Pay attention to the noise – is it a constant hum or intermittent clicks/pops? When does it happen?
3. Jack Up the Car (Safely): Support the car securely on jack stands. Never work under a car supported only by a jack.
4. Check for Play: Grab the top and bottom of the wheel and try to move it in and out (radial play) and side to side (axial play). Significant play indicates a problem, but it's not always easy to detect a small amount of play in a wheel bearing.
5. Spin the Wheel: Spin the wheel and listen for any rough spots or grinding sounds.
6. Test Drive: Pay close attention to the noises and vibrations during a test drive.
Important Note: If you're unsure, it's best to have a qualified mechanic diagnose the problem. Misdiagnosing can lead to further damage and more costly repairs. Attempting these checks yourself involves working under your car, so ensure you have proper safety equipment and knowledge before you begin.
