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Summary
  • The wheel seal prevents lubricant from leaking from the bearing cavity. It also protects the bearing from contaminants.
  • Improper installation, poor maintenance, and damaged bearings and races can cause the wheel seal to fail.
  • A leaking wheel seal can affect bearing performance, resulting in growling noises, rough cornering, and excessive play in the steering wheel.

Your vehicle has thousands of parts that can be quite difficult to keep track of in terms of performance. In some cases, you’ll only notice that something’s wrong when your vehicle starts acting up or makes unusual noises.

One of the parts that are often overlooked is the wheel bearing seal, mainly because of how small it is compared to other parts of the wheel hub assembly.

To begin with, the term “wheel seal” covers a lot of territory. Some seals are just grease seals and others are oil seals. When an oil seal fails it’s more of a problem than when a grease seal fails.

tapered roller bearings of older vehicles
The bearings in this illustration are tapered roller bearings, which are commonly used on older vehicles with this design. The grease seal is gently driven into the rotor next to the inner bearing. | Image Source: Richard McCuistian

The seals on front wheel drive hub bearings are grease seals but they’re not replaceable. They come with a new bearing. The seals on rear axles prevent oil from leaving the rear end/differential housing. All of these could be called “wheel seals.”

What Should Wheel Bearing Seals Be Checked For?

Unlike your tires, wheel bearing seals are not as visible whenever you make a quick inspection before going out for a drive, making it hard to check for visible signs of damage. However, oil leaks and grinding noises from the wheels are a few telltale signs that could point to a bad wheel seal. In most cases on newer cars, that means the entire assembly will need replacing. Grinding noises mean that the lost lubrication has allowed metal-to-metal contact that has ruined bearing.

You might also notice oil residue spattered on the dust shield, brake shoes, or brake drum, indicating a leaking wheel seal.

See also  Wheel Bearing Noise: Do You Have a Bad Wheel Bearing?
image of a leaking rear axle
Leaking rear axle seals at the drum brake area can coat the brake shoes with a greasy, oily mess that prevents the brakes from working properly. This kind of grease seal leak usually can’t be seen until the brake drum is removed and will usually show up as a brake concern. But a leaky wheel cylinder can look like this too, so check the wheel cylinder for a leak first. | Image Source: Richard McCuistian
rear wheel drive axle housing and roller bearing
Illustration showing a rear axle seal and its bearing. This is a rear wheel drive axle housing with the axle removed for clarity. This is a roller bearing that uses the axle for an inside bearing race and the seal prevents the kind of oil leakage that ruined the brakes in the top photo. | Image Source: Richard McCuistian

What Is a Wheel Seal?

A wheel seal prevents lubricant from leaking out of the bearing cavity. The lubricant is there to begin with because the bearing needs to be lubricated. Typically mounted to the hub or spindle, but most often fitted into the rotor just inside the larger inside bearing, it prevents grease from escaping and also protects the bearing from debris, dirt, and the elements.

Types of Seals

Seals can either be static or dynamic. Static seals are typically used between two stationary surfaces while dynamic seals are used between surfaces where one or both are moving. Wheel seals are typically always dynamic.

Most wheel bearings use dynamic seals that sit between the rotating axle hub and stationary spindle or axle housing. A garter spring is used to link the sealing lip to the moving part.

What Causes Wheel Seals to Fail?

There are four common reasons why wheel seals leak or fail.

Improper Installation and Maintenance

The wheel seal should fit directly onto the spindle or within the hub before you begin the mounting process. It’s also important to know that the seal has a wet/oil side that should face the sealing lip. If the wheel seal is installed backward, it could blow out and cause grease to leak.

Worn-Out or Damaged Bearings and Races

A new and properly installed wheel seal can still leak if the surrounding parts are worn-out or damaged. Pitting, spalling, and discoloration in the wheel bearings or races could indicate that they have been overheated because of oil starvation.

Clogged or Damaged Hubcaps and Axle Vents

Clogged or damaged hubcaps and axle vents can lead to a wheel seal blowout because of extreme pressure buildup. Pressure caused by heat in the wheels needs an outlet, and clogs or damages in the hubcaps and axle vents will force the seal to discharge the pressure instead.

An Overview of Your Vehicle’s Wheel Bearing

Wheel bearings are called “bearings” because they “bear” the load of carrying the car while allowing the wheels to rotate freely. In other words, the bearings support the entire weight of the vehicle.

Wheel bearings are called “bearings” because they “bear” the load of carrying the car while allowing the wheels to rotate freely.

– Richard McCuistian, ASE Certified Master Automobile Technician

Wheel bearings are designed to last as long as possible, but driving conditions and habits can affect their lifespan. On average, wheel bearings can last anywhere between 75,000 to 150,000 miles.

See also  How to Extend the Service Life of Wheel Bearings

Types of Wheel Bearings

There are generally three types of wheel bearings一ball, roller, and tapered roller.

Ball Bearings

Ball bearings are designed to operate at higher speeds compared to roller and tapered roller bearings. This type uses hardened steel balls between the inner and outer races to reduce friction. However, ball bearings are considered to be more fragile than roller bearings.

Roller Bearings

Roller bearings are designed to have a longer contact area than a ball bearing to support heavier loads. This type reduces friction by having rollers between the inner and outer races.

Tapered Roller Bearings

The tapered roller bearing is the most common type of bearing used in many vehicles. This type is designed to withstand both radial and axial loads in one direction. Unlike ball bearings, tapered roller bearings can handle more weight because the load is distributed across the entire length of each roller.

Symptoms of a Bad Wheel Bearing

These are five common symptoms that point to a defective wheel bearing:

  • Humming, rumbling, or growling noise that increases with the vehicle’s speed.
  • Rough cornering
  • Excessive play in the steering wheel
  • Pulling during braking
  • Grinding noises from the front wheels

Extending Your Wheel Bearing’s Service Life

Wheel bearings may develop problems as your vehicle racks up mileage. Here are a couple of practices to make sure they last a long time:

Avoid Harsh Driving Conditions

Muddy terrain and deep water puddles can cause the wheel bearings to wear out faster than normal because of contaminants that can infiltrate the hub assembly.

Replace Wheel Bearings in Pairs

Replacing wheel bearings in pairs ensures that both components will undergo similar conditions and have the same lifespan. Note that while this is a good practice, many shops will only replace one bearing.

Wheel Bearing Replacement Cost

You can expect to pay anywhere between $100 and $300 to replace a damaged or worn-out wheel bearing. Factors that could affect the price include the brand and your vehicle’s year, make, and model.

See also  What Happens When a Wheel Bearing Goes Out
automotive wheel hub assembly
Most vehicles use hub assemblies that come with the bearing and seal included. | Image Source: Richard McCuistian

Key Takeaways

The overall performance of your vehicle depends on hundreds of parts, including the smallest ones like wheel bearing seals. These seals are essential in prolonging the lifespan of your vehicle’s wheel bearings, which is why it’s important to check them for signs of wear or damage as soon as you notice oil leaks and unusual noises coming from the wheels. Of course, the only way you can check them is to see if they’re leaking. And if you have a differential leaking (rear wheel drive), always check the axle vent.

It’s also worth noting that damaged components like axle vents, hubcaps, bearings, and races can create problems for your vehicle even with a properly installed wheel seal.

Finding a Replacement Wheel Seal

Leaking wheel seals are dangerous, so it’s important to deal with them as soon as possible. Unfortunately, finding one that’s suitable for your vehicle at your local auto parts shops can be tricky, depending on your car, SUV, or truck. Why not skip the hassles of visiting shops by shopping online at CarParts.com?

Our website makes it easy for car owners like you to find the right wheel seal for your ride. Simply use your mobile device or computer to visit our website. Fill out the vehicle selector to narrow down the selection to direct-fit wheel seals, then use the filters to find the ones that match your preferred brand, price, and more.

We source our wheel seals from the most reliable names in the industry to ensure they’re built to last. They come with a low-price guarantee, so you don’t have to break the bank to elevate your daily driver.

On top of that, our warehouses are strategically located across the US. Order a new wheel seal now, and we’ll deliver your product straight to your doorstep in as fast as two business days.

Shop for a new wheel seal now and take advantage of our unbeatable deals.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

Bosch
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