3 Major Causes of Wheel Seal Failure (And How to Avoid Them)

Uncover the 3 major causes of wheel seal failure and learn what preventative steps you can take to avoid wheel seal downtime.
3 Major Causes of Wheel Seal Failure

Wheel ends of semi-trucks and trailers have several components that are vital to your success while over-the-road. A real make or break component is your wheel seal. This component can mean the difference between getting to your destination quickly, and being parked on the side of the road because D.O.T. has you listed as “out-of-service.”

In this article, we will uncover the 3 major causes of wheel seal failure and teach you preventative steps to avoid wheel seal downtime.

  1. What Are Wheel Seals?
  2. 3 Major Causes of Wheel Seal Failure (And How to Avoid Them)
  3. Wheelco’s Wheel Seal Recommendation

What Are Wheel Seals?​

A wheel seal plays a vital role in the longevity of your wheel bearings. Wheel seals are designed to keep your wheel bearing lubricant within the wheel end, and keep all debris, dirt, and other contaminants out while on the road. They can be installed directly into the hub or onto the spindle with dedicated installation tools, dependent upon the seal.

3 Major Causes of Wheel Seal Failure

3 Major Causes of Wheel Seal Failure (And How to Avoid Them)​

There are 3 major causes of wheel seal failure. They include the following.

  1. Improper Installation & Maintenance
  2. Incorrect Bearing Adjustment
  3. Worn or Damaged Components

Improper Installation & Maintenance​

The improper installation of wheel seals is the most common cause of wheel seal failure. Between selecting the proper fit and the use of proper installation tools, you would think proper installation would be a straight forward process. This is not the case. There are many factors during the installation process that can create headaches, if not done properly.

Did You Know? 9 out of 10 times – Improper installation is the cause of wheel seal failure.

First, correct application, your wheel seal needs to fit on the spindle or within the hub properly before actually installing it. Before you begin the installation process, you should line up the seal and inspect for a snug fit. If your seal is for a spindle mount, check this by gently sliding your seal onto the bare spindle shoulder and look for gaps between the inner diameter of the seal and the spindle. If your seal is a hub mount, place the seal over the hub and again check for any gaps between the seal and the hub. If it all lines up for a snug fit, you know you have the correct seal that should fit properly.

3 Major Causes of Wheel Seal Failure

Next, before you begin installing your wheel seal onto the spindle or into your hub, make sure you are installing the new wheel seal in the proper direction. There may be text on the seal itself telling you which is the oil side, but if not, you want to make sure your seal is installed with the sealing lip towards the “wet/oil” side. This allows pressure to push the wheel seal onto the spindle and create a proper seal. A seal that is installed backwards will eventually blow out and start leaking causing you more downtime while you repair the wheel end.

Your wheel seals should be inspected with a proper walk around before getting on the road each day. If you establish this good habit, your risk of D.O.T. finding a leaky wheel seal and labelling you “out-of-service” will decrease.

3 Major Causes of Wheel Seal Failure

Lastly, the use of proper tools during the installation of your wheel seal is a major game-changer on how successful your installation will be. Most wheel seal product boxes will contain a tool number for the proper tool to be used during the installation of the new seal. Recently, some manufacturers are even offering hand-installable seals that require no tools for installation. These hand-installable seals can be installed within minutes with the simple force of your hands. Hand-installable seals can help alleviate the hassle of selecting the correct tools. New hand-installable seals are making the job faster and easier than ever before.

When using an installation tool, place the oil side facing up. Some seal manufacturers may recommend to lightly lubricate the outside diameter of the seal with clean oil. Never use bore sealant on the seals outside diameter. Once your tool and seal are ready, drive the seal straight and firmly onto the spindle or into the hub with a 3 to 5-pound hammer. When you hear a sound change, stop driving the seal because it has now bottomed out. Over-driving will crush the seal and allow oil to leak out of the wheel end and also allow contaminants in. For spindle mount seals, run your finger along the inside of the newly installed seal to double-check for a flat and equal installation of the whole seal. For hub mounts, run your finger along the outside diameter of the newly installed seal to check for a flat and equal installation.

How To Avoid Improper Installation & Maintenance​

  • Check for the proper fit of the seal
  • Make sure your seal is facing the correct direction
  • Properly inspect seals with daily walk-around
  • Use the proper tools during installation
  • Inspect sealing surface
  • Use hand-installable seals for easy tool-free installation

Incorrect Bearing Adjustment​

The process of adjusting your wheel bearings is critical and cannot be stressed enough. Many times, people will get into a hurry and will not follow the proper procedures. The bearing adjustment procedure will make sure your bearings are perpendicular and lateral all the way around, otherwise known as being properly seated.

3 Major Causes of Wheel Seal Failure

One major mistake that many will make while adjusting their bearings is the use of an impact wrench. DO NOT DO THIS! An impact wrench can easily get away from you and you can severely over-tighten or under-tighten your wheel bearings. Instead, use a breaker bar with the proper socket size, followed by a torque wrench to tighten to the manufacturer’s specifications. You should check your manufacturer’s specifications before installing your new seal, but you can also follow the recommended RP-618 Bearing Adjustment Procedure.

When you complete the bearing adjustment procedure, you should use a Wheel End Dial Indicator Tool that will display the wheel bearing end play. A wheel bearing end play of 0.001” to 0.005” shown on the Wheel End Dial Indicator is the most common end play desired, but check your manufacturer’s specifications to be sure. Be careful when adjusting your wheel bearings, under-tightening or over-tightening your bearings can wear them out even quicker.

3 Major Causes of Wheel Seal Failure

How To Avoid Incorrect Wheel Bearing Adjustment​

  • Use a breaker bar, proper socket size, and finish with a torque wrench for bearing adjustment
  • Tighten bearings to manufacturer’s specifications or use RP-618 Bearing Adjustment Procedure
  • Use a Wheel End Dial Indicator Tool to achieve the correct wheel end play

Worn or Damaged Components​

Another mistake that people make prior to installing new wheel seals is not taking the time to completely inspect and clean all components to see if they are worn or damaged.  Dirty, worn, or damaged wheel bearings or races can have damaging effects on your equipment. While inspecting and cleaning the wheel end components, if you see any pitting, spalling, or discoloration of your wheel bearings or races, these worn or damaged components could be caused by improper installation.

Discoloration around your bearings, such as purple or yellow, means there may not have been enough oil to keep the bearings lubricated and they may have been overheated. Purple or yellow color usually means your bearings got so hot; they baked the carbon steel right out of the bearing. Always check your recommended oil capacities and follow it as close as possible at all times. The resting lubricant should be between the “fill” and “full” lines on the wheel hub window, if your machine is equipped. Improper lubricant can also cause premature failure of internal components. A synthetic GL-5 lubricant can help dissipate heat better and keep your wheel ends operating at a cooler temperature.

3 Major Causes of Wheel Seal Failure

Every time a new seal is installed, you should be inspecting and cleaning the spindle of any burrs, dings, dents, or contaminants. Contamination, like rocks, pebbles, dust, and water, can quickly deuterate the inside of your wheel ends, but to help keep your wheel end components like new, you can use solvent, a scraper and/or emery cloth to clean the wheel end. The surface of the spindle should be smooth for installation, as your inner and outer bearings will be going on this surface and you want to make sure the bearings are properly seated.

When inspecting and cleaning the spindle, you should also use a wire brush to clean the spindle threads. If the spindle threads are not properly cleaned with a wire brush, these contaminants can be mistakenly introduced into the wheel end while re-installing the wheel hub. Contaminants will move freely within the hub causing possible damage to your wheel bearings, races, and other internal components.

3 Major Causes of Wheel Seal Failure

Easily overlooked, your hubcaps and axle vents being plugged or damaged can be a factor for wheel seals leaking. As the oil in your wheel end heats up, it will begin to create pressure and that pressure needs to be released somewhere. That pressure is typically discharged through the axle vent and small hubcap vent. If either of these two are clogged or damaged, that pressure building up will find another way to discharge itself, and it’s usually through your wheel seal. A quick morning pre-check that these holes are not damaged and are free of buildup can save you from blowing your wheel seal later down the road. 

How to Avoid Worn or Damaged Components​

  • Inspect and clean all wheel end components prior to installation
  • Immediately replace components with pitting, spalling, discoloration, or other damage
  • Keep oil capacities to manufacturer’s recommendations
  • Use a Synthetic GL-5 lubricant to dissipate heat better
  • Clean threads of wheel spindle with a wire brush to avoid re-contamination
  • Check that hubcaps and axle vents are not damaged and are free of buildup

Wheelco’s Wheel Seal Recommendation​

At Wheelco, we stock only the brands we trust to successfully get the job done. National is our leading brand of wheel seals with their innovative hand-installable Dynamic Edge® Technology as well as their standard wheel seal, which require installation tools.

National® Wheel Seals​

The National® brand of oil seals and bearings has built a reputation as one of the most respected names in the industry. They provide premium quality, no-compromise solutions for virtually every wheel-end repair. National keeps pace with industry changes and provides advanced technologies to meet the needs of today’s vehicles. They are committed to providing high end, premium products that meet or exceed the original equipment specifications across the full spectrum of wheel bearings and oil seal needs.

Our Wheelco experts are ready to answer your heavy-duty questions and needs. Stop by any of our Wheelco locations or give us a call and see how we can help you stay on the road.

About Wheelco Truck & Trailer

At Wheelcobeing customer driven is more than just a motto we live by. It means that our employees will do everything we can to best serve you, our valued customer.

Customer driven is more than just offering you advice, giving time-honored service or contributing the latest tech-support. It’s about being there—whenever and wherever you need us—in-person, over the phone or online.

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