4 Rear Axle Seal Leak Symptoms & Replacement Cost

What Is A Rear Axle Seal?

Image Credit: YotaTech
Image Credit: YotaTech

Axles have three seals:

  1. One pinion seal located at the front of the differential
  2. Two rear axle seals

In this post, we’ll focus on the rear axle seals. Rear axle seals keep the differential fluid inside the axle. When the seals are doing their job:

  • Differential fluid can’t leak out the axle tube
  • Contaminants can’t enter the axle tube

There is one rear axle seal on each outboard end of an axle. The differential fluid needs to stay within the axle and differential. If a rear axle seal fails, differential fluid leaks out. That means the differential isn’t lubricated or cooled well. This can lead to a failed differential, which is an expensive repair. Replacing an axle seal is a very inexpensive repair.


What Causes the Rear Axle Seal To Go Bad?

Axle seals can go bad for a few different reasons. The most common reason is due to wear and tear. Over time, the seal starts to break down and allows oil to leak out. This can happen if you don’t regularly maintain your vehicle or if you drive it hard.

Another reason why the rear axle seal can go bad is due to an accident. If you hit something hard enough, it can cause the seal to break and allow oil to leak out. This is why it’s always important to get your vehicle checked out after an accident, even if it doesn’t seem like there’s any damage. Sometimes improper axle installation is also a cause axle seal might be leaking.


When the rear axle seal begins to leak, it can cause a number of problems. First, the leaking fluid will attract dirt and debris, which can clog the differential and cause damage. Second, the fluid itself is necessary for lubrication and cooling, so the fluid loss can lead to overheating and further damage.

If you notice a leak or any other signs that your rear axle seal may be failing, take your vehicle to a mechanic as soon as possible. They will be able to diagnose the problem and recommend the best course of action. In most cases, the replacement will be necessary.

Replacing The Rear Axle Seal On A Sterling 10.25 Axle

Image Credit: FullSizeBronco
Image Credit: FullSizeBronco

To replace the rear axle seal on a Sterling 10.25 axle, take these steps:

  1. Lift the rear of the truck to take the weight off the wheels.
  2. Remove both rear wheels.
  3. Remove all 8 bolts holding the axle in place.
  4. Remove the hub retaining hardware.
  5. Slide off the hub/drum assembly.
  6. You’ll find the rear axle seal on the backside of the hub assembly. With a pry bar or special tool, pull out the seal.
  7. Clean the bore and then put the new seal in.
  8. Put everything back together in the reverse order of removal.


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