Runny_yolk did a great writeup on changing the oil in the transfer case and transmission but he didn't get to the rear diff quite yet. Since Runny and I are friends, I thought I'd pick up where he left off.


Tools:
Gear oil pump
24mm socket (torque wrench preferable) I got my socket at Sears- they keep the bigger ones in the locked cabinet so be sure to ask if you can't find it.
Oil drain pan
Rags (to clean up)

Oil:
75W90 gear oil (I used Red Line), 1 qt is more than enough.

1. Crawl under your car and look at the rear diff. (If you do not know what the rear diff looks like, I highly suggest not doing this yourself) I did not use a jack and was able to get under. There are two 24mm bolts, one on the bottom face of the diff, and one facing rearward towards the anti roll bar. The bolt on the bottom is the magnetic drain plug. The bolt towards the rear is the fill plug.

2. BEFORE you remove the drain plug, make sure that there is enough clearance for your socket and wrench to get around to the back and loosen the fill plug. To be sure, just loosen it until it moves a bit so you know you can get it off.

3. Remove the bottom plug and drain the oil. It's not much, slightly more than half a quart. Clean the metal shavings from the plug and set it aside. Wait about 15-20 minutes for the oil to drain. Be sure when removing the plug that you get the washer as well. It sometimes sticks to the diff and it's easy to overlook.

4. Clean and replace the magnetic drain plug. I torqued it to 23 lb-ft because that's what the specs are for the transfer case and MT. (If I'm wrong correct me). Remove the fill plug on the back face of the diff. It is the same socket size (24 mm). Again, be sure not to lose the washer.

5. Insert the hose from your pump into the fill plug. To get a less kinked hose, I ran mine over the anti roll bar and then into the hole.

6. For the gear oil pumps to work well, the pumping needs to start with the oil bottle elevated. IF your pump is like mine, with an intake hose and an output hose, have a friend hold the bottle up high with the intake hose in it, so gravity will help start the pumping. Once the hoses fill up it's not so important to have the oil bottle elevated.

7. Pump, pump, pump away until you see oil start seeping back out of the diff. This should be no more than .58 quarts, but might be less due to the old oil remaining in the diff. You can never really get it all out.

8. Replace the fill plug and you're done. Drive around happily.

 

Good write up I thought the filler plug was a 17mm bolt. I guess not. Do you have any pics?

 

No, on the rear they are both 24mm. I'll take a picture tomorrow..

 

I updated my original post with a pic. bump.

 

being a lube mechanic for caterpillar, i would add the following>
do exactly what the gentleman above said except make sure do it after a long drive. The warm oil drains more effecient and you can drain a bit more out. RRR

 

Thanks. I've always thought it was that bolt but I was looking for a 17mm bolt. Thanks nsnguyen . Is the filler plug on the center differential 24mm too?

 

The center diff and front diffs are in the transfer case, I believe. The filler on that is 17mm.

 

At what mileage does this have to be done?

 

I think 15K miles, you can check in your manual for the proper interval.

 

ignore this post. Repeat!

 

OK, I feel dumb asking this Q, but I can't find them. I think I found the rear diff case, but not the rest. Where are they??? thanks for the help........

 

My rear diff is covered with undercoating... your's is nice and purddy. Anyone else have the undercoating on their diff?

 

Ok, ok, ok.... I think I found them, but I still need to verify. Someone tell me!!!!!!

 

I don't understand your question.. what are you asking again?

 

I don't think you should do the fluid change if you don't even know where your rear diff is