Wheel Bearing Failure: Will it Fail Your MOT?

The MOT test is a crucial annual inspection designed to ensure your vehicle is safe and roadworthy. While many drivers are aware of common failure points like worn tyres, faulty lights, or brake issues, some less obvious components can also lead to a failed MOT. One such component is the wheel bearing. A failing wheel bearing, if left unchecked, can indeed result in your vehicle failing its MOT, and understanding why is vital for any car owner.

What is a Wheel Bearing and Why is it Important?

At its core, a wheel bearing is a simple yet incredibly important part of your vehicle's drivetrain. It's a ball bearing or roller bearing that allows the wheel to rotate with minimal friction. Essentially, it's the intermediary between the wheel hub and the axle. Without properly functioning wheel bearings, your wheels wouldn't be able to spin freely, making driving impossible and, more importantly, extremely dangerous. They are responsible for supporting the vehicle's weight and allowing the wheels to turn smoothly as you steer and accelerate.

Signs of a Failing Wheel Bearing

Recognising the symptoms of a failing wheel bearing is the first step in preventing an MOT failure and avoiding potentially catastrophic accidents. The most common indicator is an audible noise. This usually starts as a grinding, rumbling, or humming sound that gets progressively louder as you increase speed. This noise might also change when you turn; for instance, it could become louder when turning left if the right-side bearing is failing, and vice versa. Another sign can be a vibration felt through the steering wheel or the floor of the car, particularly at higher speeds. You might also notice uneven tyre wear, as a damaged bearing can cause the wheel to wobble slightly, leading to premature and irregular wear on your tyres. In severe cases, you might even feel a looseness or play in the wheel when you try to move it by hand with the car jacked up.

How the MOT Test Inspects Wheel Bearings

During an MOT inspection, the tester will specifically check for excessive play or looseness in the wheel bearings. The most common method for this involves lifting the vehicle on a ramp and then grasping each wheel at the top and bottom, attempting to rock it back and forth. If there is significant movement or 'play' in the bearing, this indicates wear and tear. They will also listen for any unusual noises that might suggest a worn bearing, especially during the test drive portion of the MOT. The guideline is that there should be no perceptible movement or looseness in the bearing. Even a small amount of play can be enough to fail the test, as it signifies a component that is no longer functioning as it should and could compromise safety.

Why Wheel Bearing Failure Leads to an MOT Failure

The primary reason a faulty wheel bearing will cause an MOT failure is safety. A wheel bearing that has worn to the point of having excessive play can lead to a number of dangerous situations. Firstly, it can cause the wheel to wobble or even detach from the hub at speed, which is an obviously catastrophic failure. Secondly, the increased friction from a damaged bearing can generate significant heat, potentially leading to brake failure if the heat transfers to the brake components. Thirdly, the instability caused by a worn bearing can affect the vehicle's handling and steering, making it difficult to control, especially during emergency manoeuvres. The MOT test is fundamentally about ensuring a vehicle is safe to be on the road, and a compromised wheel bearing directly undermines this.

Can You Drive with a Failing Wheel Bearing?

While your car might still be driveable with a worn wheel bearing, it is strongly advised against continuing to drive it for extended periods. The symptoms will likely worsen, and the risk of a complete failure increases significantly. As mentioned, the noise will become more pronounced, vibrations can become more severe, and the structural integrity of the wheel assembly is compromised. Driving with a failing wheel bearing is not only a safety risk to yourself and other road users but also a risk to your vehicle, as further damage can occur to other components, such as the hub, driveshaft, or brakes, making the eventual repair much more expensive.

Repairing or Replacing Wheel Bearings

Replacing a wheel bearing is a job that requires specific tools and a good understanding of vehicle mechanics. While it's possible for a skilled DIY mechanic to tackle it, it's often best left to a professional. The process typically involves removing the wheel, then dismantling various components of the hub assembly, including the brake caliper, brake disc, and potentially the suspension components, to access the bearing. The old bearing is then pressed out, and the new one is pressed in. Proper seating and greasing are crucial for the longevity of the new bearing. Due to the specialised nature of the job and the critical safety implications, it's highly recommended to have this work carried out by a qualified mechanic.

Cost of Wheel Bearing Replacement

The cost of replacing a wheel bearing can vary significantly depending on the make and model of your vehicle, as well as your location and the garage you choose. Generally, front wheel bearings are often more accessible and can be slightly cheaper to replace than rear ones, especially if they are integrated into the hub assembly. For a single wheel bearing replacement, you can typically expect to pay anywhere from £150 to £400. This cost includes both the part itself and the labour involved. It's always a good idea to get a few quotes from different garages to ensure you're getting a competitive price.

Preventative Maintenance for Wheel Bearings

While wheel bearings are designed to last for a considerable mileage, they are still subject to wear and tear. There isn't a specific maintenance schedule for wheel bearings in the same way there is for oil changes or tyre rotations. However, some general practices can help prolong their life. One key aspect is avoiding harsh impacts, such as hitting potholes at high speeds or driving over rough terrain unnecessarily. These impacts can shock the bearings and accelerate wear. Regularly checking for any early signs of damage, such as unusual noises or vibrations, and addressing them promptly is also crucial. If you're having other work done on your vehicle that involves the wheel hub or suspension, it might be a good opportunity to ask your mechanic to inspect the wheel bearings for you.

Frequently Asked Questions

Q1: How long do wheel bearings typically last?

Wheel bearings are generally designed to last the lifetime of the vehicle, often exceeding 100,000 miles. However, factors like driving conditions, maintenance, and manufacturing defects can significantly impact their lifespan.

Q2: Can a loose wheel bearing be fixed without replacement?

In most cases, no. If a wheel bearing has developed significant play or wear, it cannot be adjusted or tightened; it will require complete replacement to restore proper function and safety.

Q3: Does a wheel bearing make noise when turning?

Yes, a common symptom of a failing wheel bearing is a noise that changes when you turn. It typically gets louder when turning in the direction opposite to the faulty bearing.

Q4: Is it expensive to replace a wheel bearing?

The cost can vary, but a typical replacement for one wheel bearing can range from £150 to £400, including parts and labour. This is a reasonable cost for a critical safety component.

Q5: Can I pass my MOT if my wheel bearing is slightly worn?

The MOT tester will check for excessive play. If the wear is minimal and there is no perceptible looseness or noise, you might pass. However, any noticeable play is likely to result in a failure.

Conclusion

In summary, a failing wheel bearing can absolutely lead to an MOT failure. The MOT test prioritises vehicle safety, and excessive wear or play in a wheel bearing is a significant safety concern. By understanding the signs of a failing bearing, the checks performed during an MOT, and the importance of timely repairs, you can ensure your vehicle remains safe, roadworthy, and passes its annual inspection with flying colours. Don't ignore those tell-tale noises or vibrations; get them checked out promptly to avoid an MOT failure and potential danger on the road.