Rear Outer Axle Seal Replacement
Date: 7/28/2007
By: Bob_98SR5


Parts
Toyota Rear axle outer seal (some people have had good luck with Napa seals)

Tools and Supplies
Red Loctite (I believe this is the strongest one)
Rear differential fluid and pump
Seal puller (91352) and driver kit (35555) from Harbor Freight.

Disclaimer
Property of 4Runners.org. I am providing this write up for illustrative purposes only. Perform at your own risk. Any mods (including this one) you perform on your vehicle is your responsibility. Commercial use of this write up may result in legal action.


Summary
Over time, many Toyota truck owners experience fluid seepage near the rear drums. Almost always, this is a symptom of a blocked differential breather not allowing the heated air pressure to vent from the rear axle tube. The good news is that with a friend, you can easily change the rear axle seal in an hour or two.

Step 1: Removing the Tires and Draining the Rear Differential
Begin by lowering your spare tire and moving it out of the way. Now chock your rear wheels and jack up your 4runner and set your jack stands in place. Unbolt the 12mm rear brake cable bolt. This will allow you to maneuver your 24mm socket on the ½ inch socket wrench onto the top 24mm (fill) bolt. Turn it counterclockwise to remove the plug. After removing this plug, remove the bottom 24mm drain plug. Allow it to drain out.

Note: one reader provided me feedback that the 24mm drain bolt is soft metal. He used a 12 point instead of 6 point socket and rounded it off. Thus as a precaution, use a 6 point socket and use some PB Blaster the night before to loosen the plug.

    
Lower the tire by cranking counter-clockwise   Unbolt 12mm bolt (P) to allow room for your 24mm socket; remove fill bolt (F) first and then drain bolt (D)

While your vehicle is still on the ground, use a 21mm deep socket and a cheater bar to loosen up the lug nuts on each rear tire. Next, pull your e-brake, chock your front tires, and jack up your vehicle at the rear axle pumpkin. Set the jack stands on the rear frame and bring your vehicle slowly down on your jack stands. Once the tire is off the vehicle, remove the retaining pin from the emergency brake lever mechanism at the backing plate and move the cable out of the way. Then, the hydraulic brake line can be removed from the backing plate. If you don't have a flare tool, remember the line fitting nut is soft and subject to rounding off, so be careful.

After you've removed all three tires, drain the rear differential fluid.

  
Loosen the lug nuts, lift and remove the tire   Drain out the differential fluid. Pull the fill plug first!


Step 2: Unhooking the Brake Lines and Backing Plate Nuts

Using a 10mm wrench, unbolt the brake bleeder connector at the end of the backing plate. There will be some residual brake fluid loss, so tie a baggie around the end or place a drain pan under the end of the axle tube. Next, using a 14mm socket wrench, undo the four hex bolts as shown in the picture below. You are now ready to remove your rear axle shaft.


Remove nut (L) and 4 nuts (N)


Step 3: Removing the Rear Axle Shafts
This is a job best done with a friend. With one person grabbing the backing plate and pulling the axle shaft out, the other person should be making sure that the end of the axle shaft does not scratch or gouge the inner shaft wall itself. Pull out the axle shaft and place it on a towel or cardboard box. The shaft should be pointing upwards to the sky so as to avoid any damage or dirt from contaminating the splines. If you want to be extra careful, wrap a baggie around the end of the shaft splines.

Yes, it stands up all on its own!


Step 4: Removing and Reinstalling the Seal

Using your seal removal tool, remove the seal and discard it. You may need to give it a little pull to get it out, as it is seated fairly well from the factory. Wipe down and clean out the inner surface of any dirt, contaminants, or residual seal material before reseating your new seal. Put some differential fluid on the outer part of the seal itself and then use your seal driver to reseat the seal. If you don’t have a seal driver, many people have used a 2 1/8” front hub socket with a towel on the end to drive the new seal. Once you’ve finished seating the seal, coat the inner axle tube surface with differential grease.

     
Here's the seal. Mine was still good, but might as well replace it at 120k miles   Here's a picture of a seal puller    And here is a seal driver kit

You are almost done. Reinstall everything else in reverse order. On the four 14mm backing plate bolts removed in Step 2, make sure you put a little Red Loctite on the threads before reinstalling and torque down to 51lbs.

Step 5: Brake Fluid and Rear Differential Fluid Replenishment
Because you’ve depressurized the brake fluid lines, you will need to replace your brake fluid and bleed the air out of the brake lines. This procedure is contained in my writeup on brake bleeding.

In addition, you will need to add some rear differential oil in the rear axle. You may choose to top off or completely drain and replenish it. Read my differential fluid writeup here to see how its done.

 

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