A methodical approach to this meticulous job for a Jeep JK is essential for successful results.
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Words and Photos by Peter Boyer
Rear axle seal failures are not uncommon on Jeep Wranglers. But, with the severe use that the seal encounters in a 4X4 rig, and its minimal design, it’s surprising that it doesn’t fail more often. This repair is fairly straightforward, as we shall see, except for the requirement to use some specialty tools that may be out of the comfort zone of some DIY mechanics.
However, don’t be intimidated. Like all mechanical repairs, a careful step-based approach, an understanding of the functions of each component involved and having the right tools for the job makes these repairs much easier with efficient results. If you decide to have your local shop do it for you, you’ll get a clear understanding of why it costs what it does for the parts and labour!
One telltale sign that the axle seal has failed is the noticeable oil at the bottom of the backing plate of one of your rear wheels or an oil-spray mark on the inside of the rear tire. This seal is designed to contain the gear oil in the differential and axle tube, while allowing it to lubricate the rear wheel bearing located at the far end of the axle, where the rear brakes and wheel bolt on at the axle hub.
WHAT CAUSES A REAR AXLE SEAL TO FAIL? Longevity
Some seals seem to last forever, but many don’t. Friction from the axle shaft spinning on the tight, thin lip of the seal simply wears and in the case of my 2011 JK with low mileage, I suspect that age is a factor as the flexible compound the seal is made of lost resilience and was no longer able to hug the axle shaft tightly enough to retain the gear oil.
Normal deterioration happens slowly, which is why it’s important to inspect your vehicle regularly, particularly once it exceeds 100,000 km (62,000 mi). If a small oil leak goes unnoticed, it will only increase, and accumulate to contaminate the nearby brake components, increasing the cost of the repair.
Premature Failure
Premature failure may include a defective seal, improper installation, or inadequate maintenance related to exposure to dirt and other contaminants. A defective seal is the least likely of these possibilities given today’s quality manufacturing capabilities (but it could occur, nonetheless). A more likely cause of premature failure is a recurring repair from improper installation the first time, such as improper alignment during installation, or a scored axle shaft during bearing removal.
My speculation is that most premature rear axle seal failures on Jeeps are caused by dirt, water, and rust compromising the external surfaces of the axle. Going off-road exposes chassis components to mud, sand, gravel and water. It’s extremely difficult to clean a chassis after total immersion in muddy water even with a pressure washer. This is where regular brake service is important as components are disassembled, checked and cleaned thoroughly with brake cleaner and compressed air. Even though the seal is somewhat protected inside the hat of the rear rotor, it’s amazing how much debris can accumulate in the area, thus causing the need for replacement. Here are the steps to replacing a damaged seal.