The seal itself is rubber bonded to a metal casing, with a flanged lip that bears on the axle. It relies on a tiny amount of lubrication from the fluid it holds in to minimize wear.
In addition to keeping oil in, the seal keeps the grit and moisture out. Most often, seal failures are simple wear and tear; most often noticed as fluid leaking out.
In other cases, the bearing behind the seal can fail; causing more play in the axle shaft than the flexibility of the seal can manage.
Cost of Replacing the Axle Seal
Some examples of the axle seal leak repair cost in some common vehicles using $100 an hour as a labor rate are as follows:
- On a 2004 Toyota Corolla, the labor time for a front axle seal replacement (one side) is 2.6 hours and a Beck/Arnley seal costs about $7. Total job cost would be $267.
- On a 2014 Chevrolet Impala, the labor time for a front axle seal replacement is 1.2 hours. An OE AC Delco seal costs about $7. All of these make up for the total cost of around $127.
- On a 2005 Chrysler Pacifica AWD, there is an axle seal on each of the front and rear axles. The labor time for each is 1.1 hours. An OE axle seal is about $25 and an aftermarket SKF seal is about $13. The axle seal replacement cost in this instance will be around $123 using aftermarket parts or $135 using OE parts.
- The axle seal on the rear of a 2000 Ford Ranger takes 1.2 hours of labor time. A National seal costs about $7; making the job about $127 in total cost.
- On a 1999 Toyota Tacoma, the rear axle seal and bearing must be replaced together. The labor time for that is 1.7 hours, a Timken bearing is about $42, and the two seals needed for a side cost about $8. Total cost would be $220 all in all.
If an axle seal is replaced in conjunction with other work that makes it accessible, such as a drive axle replacement, the labor for the axle seal is usually about a two-tenths of an hour additional charge added to the other labor charges.
How To Repair/Replace Axle Seals?
Almost all front-wheel drive vehicles use CV axles to run engine power from the transaxle to the wheels. On the transmission side, the axle splines into the transaxle housing and an axle seal holds the transmission fluid in at that point.
The metal housing of the seal grips the transaxle case and the rubber lip of the seal rides on a machined surface of the axle. All-wheel drive vehicles often use the same kind of seal if they have an independent suspension; usually running the axles from a differential rather than directly from a transaxle, but otherwise similar in principle and in repair procedure.
In some cases, the axle isn’t splined directly into the transaxle or differential but bolted to a flange that is splined in. Replacing an axle seal is nevertheless fairly simple in most cases. It involves removing the axle and the axle flange (if one is used), pulling the seal, installing a new seal, and then, reassembly.
There is another variety of axle seal used in vehicles with solid rear axles – commonly on light trucks. This itself has two types. In the first, a solid axle shaft runs from the differential through the axle housing to the wheels.
To replace the axle seal, the differential cover is removed and a locking mechanism is disassembled, then, the axle shaft can be drawn out. The axle seal fixed into the end of the differential housing at the wheel can then be replaced.
In the second kind, the solid rear axle shaft is locked at the wheel end. A rigid flange carrying the axle seal slides onto the axle and is bolted to the rear differential housing.
This flange is fixed in place by a bearing pressed onto the axle inboard of the flange. In this case, the axle bearing must be removed and replaced along with the seal.
A leaking axle seal is fairly easy to diagnose and seldom misdiagnosed. A very slightly leaking seal that only leaves residue and doesn’t affect fluid levels may not be critical to replace.
A leak significant enough to drip from the housing or leave puddles where the vehicle is parked should probably be addressed sooner rather than later. A leak from a rear axle seal will, because of how it is placed, generally coat the rear brake pads or shoes. Most often this should be fixed as soon as it is noticed.
Other Things That Might Come Up
A part of replacing the axle seal is topping off the transmission fluid to replace what has leaked. If the fluid is notably worn or past scheduled service, then, a transmission service would probably be recommended at the same time.
On rare occasions, a seal may fail not because of ordinary wear but because the bearing it protects has failed; allowing excess movement of the axle. Usually, in that case, noise or vibration would be noticed. However, if play in the transmission output shaft is found, more repairs may be needed.
One general rule in automotive repair is that whenever a suspension part between the wheels is removed or replaced, checking the alignment is a good idea. The axles must be removed to replace axle seals.
In many cases, this can be done and reassembled without disturbing the alignment. However, this is not always the case and there are often several ways of disassembly to remove an axle depending on unpredictable conditions. If an alignment is recommended, it’s probably the best thing to do.
It’s also ideal that if an alignment is not recommended, pay attention to how the vehicle drives after the repairs are done. If the steering wheel has changed position or any handling issues are noted, very likely an alignment should be done.
The replacement of a rear axle bearing on a solid axle vehicle has no implications on the wheel alignment. But it is often recommended on the first type to replace the bearing as well, as it is more often a cause of seal failure in that case.
In the second case, bearing replacement is required as the bearing is inevitably damaged when it is removed to access the seal.
One common issue with both of these rear axle seal varieties is that when the seal leaks, it leaks into the braking system. Most often, if brakes are contaminated with differential oil, it is recommended that they are replaced; adding significantly to the cost. Rotors and drums can be cleaned, but pads or shoes that have absorbed oil are usually not considered reusable.