One of the most overlooked yet highly critical parts of the drive-axle and steering assembly are the wheel bearings. Every wheel on your car is attached to a hub and inside this hub is a set of lubricated wheel bearings that allow your tires and wheels to spin freely without building up too much heat. They are engineered to last a very long time, but eventually, they will lose their lubricity, wear out, and need to be replaced. They can even become loose from wear inside the wheel hub assembly. If they break entirely, it can cause a wheel/tire combination to fall off the car while at speed, leading to a very unsafe driving situation.
Prior to 1997, most cars, trucks, and SUVs manufactured and sold in the US had an inner and outer bearing on each wheel that was recommended to be serviced every 30,000 miles. As technology improved, newer vehicles were equipped with a "maintenance free" single wheel bearing designed to extend the life of wheel bearings without having to be serviced. From time to time, these "indestructible" wheel bearings will wear out and need to be replaced before they break.
Here are 4 warning signs that are rather simple to recognize and indicate a worn-out wheel bearing that needs to be replaced.
1. Abnormal Tire Wear
There are many individual mechanical problems that can lead to abnormal tire wear including under or over-inflated tires, CV joints, struts and shocks, and a misaligned suspension system. However, one of the most common sources of uneven tire wear is worn out wheel bearings. It's very rare for wheel bearings to wear evenly. As such, if the left tire is showing more wear, it might indicate a problem with the left wheel bearing. Still, wheel bearings need to be replaced together; if there is a problem with one side, you need to replace the other wheel bearing on the same axle. If you or a tire technician notice one side of your vehicle's tires wearing out quicker than the other, contact an ASE certified mechanic to road test and diagnose the cause of this tire wear. In many cases, it can be something different or minor, but you don't want to risk having a wheel bearing break.
2. Roaring or Grinding Noise from the Tire Area
It's very difficult to detect a failing wheel bearing because it happens infrequently and when they do wear out, it can happen fast. That being said, one warning sign of a worn out wheel bearing is a loud grinding or roaring sound coming from the tire area of your car. This is caused by excess heat that has built up inside the wheel bearing and lost most of its lubricity. Essentially, it's a metal-to-metal sound you're hearing. It's also common that you'll hear this from one specific wheel and not both sides at the same time, indicating uneven wear. Like the above issue, if you notice this warning sign, contact an ASE certified mechanic as soon as possible so they can diagnose the source of this sound and fix it before it becomes a safety issue.
You might also hear snapping, popping or clicking sounds that may indicate a bad wheel bearing. Though usually an indicator of a worn CV joint, a snapping or clicking sound may be caused by inadequate bearing clamping. It may be especially noticeable when taking making sharp turns.
3. Steering Wheel Vibration
Another common symptom with other mechanical problems in the drive and steering assembly, a vibration in the steering wheel can be caused by worn out wheel bearings. Unlike a tire balance problem that typically shows up at higher speeds, a vibration in the steering wheel due to a bad bearing will be noticed at slower speeds and progressively get worse as the vehicle accelerates.
4. Additional Play in the Wheels
This is not very common for normal car owners to diagnose. However, if you have the tire jacked up or the vehicle is on a hydraulic lift, you can check this one out yourself. Grab the wheel on opposite sides and attempt to rock it back and forth. If the wheel bearings are good, the wheel won't "wobble." However, if the tire/wheel assembly moves back and forth, it is most likely due to worn out wheel bearings that need to be replaced as soon as possible.
Additionally, if you notice the vehicle has a hard time rolling while the clutch is depressed or the vehicle is in neutral gear, it can be caused by wheel bearings that are worn out, creating friction, and could be failing.
Anytime you notice any of the above symptoms of a worn out or failing wheel bearing, contact a dependable ASE certified mechanic who will road test, diagnose and replace the wheel bearings if needed.