How to Change a Rear Axle Seal
Here are some general instructions explaining how to change a rear axle seal on most vehicles. There are a few things needed, like:
1. Drain pan - Make sure to have this so you can catch any excess oil that may still be in the differential.
2. Jack, Jack Stands, and Wheel Chocks - Make SURE to use the jackstands, as they will save your life. Chock up the front wheels, as you might have the entire rear end up in the air.
3. Lug Wrench - To get the tire off.
4. Socket and Wrench Set - To remove the cover on the differential, and get the axle loose from it.
5. Seal puller/installer or other suitable tool - To remove and replace the seal. A screwdriver and a big socket usually work fine, if you don't have the tool.
6. Gear Oil - to put back in the rear end.
7. The new seal - The reason you are reading this.
8. Depending on design of the differential - a tube of Black RTV - Some covers are actually 'hammered in' You will want to get those loose with a hammer and screwdriver and break it loose little by little around the edges. Some axles unbolt straight from the rear end without having to remove the differential cover, and others have a pin and a clip that has to be removed from the differential to slide the axle out.
Now that we have the basic list of items needed to complete the job, The first obvious thing to do is to get that wheel off. So, get the jack and jack stands close along with the lug wrench, and loosen the lugs a little bit. Now it is time to jack the wheel up, and place jack stands under the rear end, so it does not move. Then take the wheel off the rear, and use it as something to sit on. Once the wheel is off, and the vehicle is safely supported, you will need to remove the rear brake drum to see inside there and get the axle off. On some bigger trucks, that is all that is required to pull the axle is to remove the brake drum.
As you can imagine there are many different ways axles can be held into the rear end. The only safe thing to say at this point is to consult the service manual for the vehicle. I am going to assume this is for a Chevy though, and keep going with the instructions, because they seem to be the most common ones to have rear axle leaks (besides the bigger trucks). If there is no way to unbolt the axle and slide it out, then there is a C-Clip inside the differential holding it in place. In this case, you will need to jack up both rear wheels, and secure them, but not necessary to remove the other wheel. This is so you can turn it once you get the cover off. So put the drain pan under the differential and start unbolting the cover.
When you get the cover off, and everything else drained out of there, you will want to spin the rear end, until you can see the pin that comes out of the center. This pin holds the axles in the differential, deep enough so the C-lips do not fall out. Once you remove that pin by unscrewing it, push the axle that is to be removed in, and remove the c-clip from inside the differential. Now you can slide the axle out.
Once the axle is out, changing the seal is fairly straightforward. Use your tools to change the seal, just make sure that the 'solid' part of the seal is towards you, and it will hold the oil in better. When you tap it in, make sure that it goes in straight and that it goes all the way down. There is no need to hit the seal very hard, as they usually are soft enough to just press back in with your fingers, if you get the rubber ones.
Putting it back together is reverse of removing it. The only thing extra that you will need to know is how to refill the system.Check out this article about how to change the rear gear oil, for those tips and instructions.
General instructions is usually all someone needs, but be sure to check your service manual, because there may be something very specific to your vehicle, before trying to do any repairs. Stay safe, and keep your car running for as long as possible!
