Replacing Rear Axle Seals - 3rd Gen 4Runner
Dcrim1 shows you how to replace the rear inner oil seals.
Replacing the rear oil seals is not a very tough job. It takes a few simple tools and about $20 in parts. It took me about two hours. Here's how you do it.
Oil seal (Timken #1960 at Autozone)
Diagram of axle assembly
Step 1: Removal of tire and brake drum
Remove the tire and the brake drum. My drums slipped right off with no resistance. After I removed the drum I immediately noticed that everything was covered in gear oil. It was the classic symptom of a blown oil seal.
Step 2: Removal of the axle
This step sounded very daunting to me but actually turn out to be very easy. Make sure you place an oil pan under the axle. It gets really messy.
The first step is to detach the parking brake cable and power brake line from the back of the plate. The parking brake cable can be easily detached by removing the pin in the linkage. The brake line requires a 10 mm wrench to unscrew the fitting. Make sure you plug the exposed end of the brake line or all your fluid will drain out (Trust me, I know this from experience).
Then, remove the four nuts that secure the plate to the axle housing (See Picture 1). These require a 14 mm wrench. Once you have removed these four nuts, you can pull the axle out. It may require a bit of tapping and prying to break the plate free from the housing. Once it is loose, carefully pull the axle out. NOTE: You will notice that there is an O-ring (Picture 2) where the plate seals to the housing. I just cleaned the surface and left mine on there since it was still in good condition.
Step 3: Removal of old oil seal
Look inside the axle housing and you will see the oil seal (See Picture 2). Getting the old seal out can be tricky. The Haynes manual recommends a special seal removing tool or just using a screwdriver to pry it out.
I didn't have the tool so I tried the screwdriver. It wouldn't budge. Since the seal was going to be replaced anyway, it didn't matter if I damaged it. So, I pounded a large flathead screwdriver into the seal itself. After making a few holes in the seal and bending it (be careful not to damage the inside of the axle housing), I was able to pull it out with some pliers. Again, be careful not to damage anything but the seal.
Step 4: Installation of new seal
Wipe down the inside of the axle housing to make sure there are no metal shavings or dirt in there. Place the new seal (See picture below) in as far as you can by hand, making sure it is a square as possible. This is tricky because of the magnetic ABS sensor which gets a really good hold on the seal as you stick it in there. You could remove the sensor but I was able to do it with it in place. Then, take a large socket or something of about the same diameter as the seal and pound it into its seat. It will be tough but keep pounding until it is seated. Make sure you don't tweak the seal. Once it is in, coat the rubber part of it with some new oil.
Step 5: Finishing up
Insert the axle back into the housing making sure not to damage the new seal. Make sure the O-Ring is in place. Install everything in the reverse order and top off your differential oil as needed. The four nuts that secure the plate to the housing need to be torqued to 48 ft/lbs. You will then need to bleed your brakes. You should only need to bleed the line that you disconnected.
Refer to Gadget's site for a great write-up on brakes