All vehicles today are front wheel drive, rear wheel drive, or all wheel drive. Each vehicle has an axle that provides power transfer to the wheels. Each axle is different in every way and has two to three seals on them.
There are three types of axle seals on rear wheel and four wheel drive front axles:
- Pinion seal (most common leak)
- Axle shaft seal
- Axle cover seal
Axle seals are designed in two categories
A static seal is made to connect two surfaces together without allowing any form of leakage. These two surfaces are non moving at any time. Like on the axle, the static seal will be the axle cover seal.
A dynamic seal is made to seal a cover or housing around a moving part or shaft. The seal performs two jobs, keeps the fluid in and keeps the dirt or contaminants out. Like on the axle, the dynamic seal would be an axle shaft seal or pinion seal.
It can be tricky to replace an axle seal on vehicles. First thing is to know where the leak is coming from. Keep in mind that on transverse (or front wheel drive) vehicles tend to have a valve cover leak from the engine and leak down onto the transmission then out to the axle shaft. Most repairs are replacing the axle shaft seal, but this process is not the correct fix for the situation.
Transverse or front wheel drive
Axle seals on transverse mounted units can be tricky to replace. Some vehicles have an engine guard covering the bottom of the engine and the entire transmission. This can be tricky to remove, but not impossible. Most front wheel drive systems require you to remove the lower control arm and leave the strut hanging, thus leaving enough room to extract the constant velocity shaft from the transmission. Once the constant velocity shafts are removed, it can be quite simple to remove the axle shaft, however, if there is a cross member right under the axle then there may be some difficulty taking out the seal. The best way is to use a seal remover tool that can be used in any direction. This aids in the axle seal removal.
Installing the seal will require some strategy for proper alignment. This can be done with using the proper seal installation tools. Once the new seal is in place, putting the suspension components back together can be troublesome at times but not difficult.
Rear wheel drive
When replacing a seal on a rear wheel drive vehicle, there may be tricky situations where something may be in or near the location of the seal and preventing quick extractions. Example would be a spare tire could be in the way of the axle cover seal making it difficult for removing the mounting hardware.
For the most part, seals can be tricky to gain access to and or remove depending on the type of seal and nature of the seals condition. Each vehicle is different and has many different obstacles to overcome prior to an axle seal replacement. Automotive specialists at YourMechanic would be happy to help you with this service.
This article originally appeared on YourMechanic.com as Why Axle Seal Replacements Can Be Tricky and was authored by Marvin Sunderland.