HOW TO: Rear Diff Check/Replacement of Fluid [Archive] - North American Grand Cherokee Association

: HOW TO: Rear Diff Check/Replacement of Fluid


Zj95Maxx
10-12-2006, 07:18 PM
Difficulty-Average
Time-1 hour to an hour and a half



Ok, I decided to do this because I have been having problems with smells and popping, so I decided to check alot of things on my jeep. I am showing you how to change your rear diff fluid and to check for anythign that you don't want to find.
This is my own work, I do not want anyone giving me crap if they tried and failed to do this, use if you need it, but in the end, you did it, not me. So here we go.

First thing you gotta get are supplies. Here is what I used:
Newspaper to cover the ground you are working on(Don't want oil on your floor, do you!)
Plenty of rags,towles or anything else to clean up spilled stuff
Gasket Scraper
Lint Free Cloth
Rubber Mallet
RTV sealant
Brake Cleaner
Gear Oild Fluid. I used 75-90W
Limited Slip Fluid( If you have a limited Slip Diff)
Wrench Or Socket set. I think the bolts are 1/2 if I remember correctly.
Wide Pan to catch the oil

That is what I used, Use whatever else you want or dont use some of the things I used, It is up to you!
Lets get started:
The Reason I decided to check and reseal it was this.
http://i16.photobucket.com/albums/b37/chewning37/helpje001.jpg
Looked like it was leaking a bit.

First you want to prepare your area, I layed down a bunch of newspaper around the entire area where I was working, Set all my tools and fluids next to me so I wouldnt have to keep getting out from under the jeep
http://i16.photobucket.com/albums/b37/chewning37/helpje002.jpg
My Rear Diff is a Dana 35, so my fill plug is just rubber, I think on the dana 30's its a bolt you have to take out. Either way, take off the plug and let whatever fluid comes out, come out.
http://i16.photobucket.com/albums/b37/chewning37/helpje003.jpg
Then, after that fluid has come out, loosen all the bolts but the top one. Then remove all the bolts except the top one.
http://i16.photobucket.com/albums/b37/chewning37/helpje004.jpg
Then loosen the top bolt but do-not remove it quite yet.
You can get the diff fluid to drain by 2 ways, CAREFULLY prying at the cover with a screw driver, or you can do what i did, and take a rubber mallet and whack the side of it untill the old gasket material breaks loose and the fluid drains.
http://i16.photobucket.com/albums/b37/chewning37/helpje005.jpg
It is quite a good amount of fluid that pours out, so be ready for it.
Now you can remove the top bolt and pull the cover off, more fluid will come out, so be prepared.
http://i16.photobucket.com/albums/b37/chewning37/helpje006.jpg
Now you can see the gears, but first check the fluid you just drained, HOPEFULLY you will NOT find any metal flakes or anything in it, Mine was metal flake free so I am happy. If you DO find flakes, you have a problem that must be handled on another day.
http://i16.photobucket.com/albums/b37/chewning37/helpje007.jpg
As you can see, mine is flake free.
Now as the last of the diff fluid drains, start scraping the old gasket material off the cover.
http://i16.photobucket.com/albums/b37/chewning37/helpje008.jpg
Do this very carfully, using a tool that is for this, you dont want to chip anything. Make sure you get ALL the gasket material off so you can have a leak free seal. Use your Lint free cloth to get the excess oil and gasket material out. You can use brake cleaner to get stuck gasket material and excess oil out of the cover, when your done, it should be very clean, like this.
http://i16.photobucket.com/albums/b37/chewning37/helpje009.jpg
Now you are going to need to get the gasket stuff off the outside of the diff itself, put a paper towl or something over the diff gears, so no gasket material or dirt gets in the gears, that would be bad.
http://i16.photobucket.com/albums/b37/chewning37/helpje010.jpg
Make sure you do this good the first time or you will have to REseal it.
When your done, it should look like this.
http://i16.photobucket.com/albums/b37/chewning37/helpje011.jpg
Now, make sure your cover is clean once more, and apply your RTV seal to the cover. Use whateer seal you choose and put as thick of a bead of it around the case as you feel needed, I used about a 1/4' bead. Go all the way around the cover and go around the holes, like this.
http://i16.photobucket.com/albums/b37/chewning37/helpje012.jpg
Do not let the sealent sit for more than 5 min or it will harden, Put the cover on the Diff, carefully, trying to line up the bolt holes and not smearing the sealent if at all possible, shove the bolts in the holes, and finger tighten all of them.
Then, It says on my RTV to let it sit before tightening, but its not necessary I personally think, and went ahead and tightened them. Do them in the star partern if possible, so it tightens evenely around the diff. When your done it should look like this.
http://i16.photobucket.com/albums/b37/chewning37/helpje013.jpg
Now add your favorite gear oil (add limited slip fluid before the gear oil if you need it) I used about 1 1/2- 2 bottles of oil, fill untill it starts coming out of the plug.
http://i16.photobucket.com/albums/b37/chewning37/helpje014.jpg
You might need to use a funnel or something to get the fluid in.
Plug her up and you are done! Do a couple of figure 8's to distribute the fluid throught the diff. I could not drive the jeep at the time, so I just jacked up the jeep on each side to move the fluid. Check everything you have done, take the oil to wherever you need to.
Congratulations!
Hoped this helped someone. Like I said before, This is how I did it, other people may do it diffrently so read around and find the way you like the best and go for it!

bringselpup
11-04-2006, 09:55 AM
Ok so I've stocked up on gear oil and I'm ready to try it.

Why the RTV sealant instead of the gasket they sell? Is it a better seal?

Zj95Maxx
11-04-2006, 05:33 PM
I dunno, its really the same thing

bringselpup
11-04-2006, 06:19 PM
Well I did the rear first today and when I popped the cover I found RTV so I went and got a tube of Ultra Black and that's what I used.

I did some scraping to remove the bigger chunks and then put a nylon paint stripper wheel in a hand drill and cleaned the mating surface up like new.

Zj95Maxx
11-04-2006, 07:14 PM
Thats a good idea, I didnt have it at the time, so just an old g-scraper for me

bringselpup
11-05-2006, 02:12 PM
Did the front today. Note to self: get the drain plug out before cracking the hatch. That sucker is in there but good. Had to put the cover back on with a couple bolts to loosen the drain plug.

93JeepZJ
01-21-2007, 10:10 PM
old post but question... on the rear diff cover, what did u do so fluid doesnt leak out the rubber plug? mine leaks in the same spot and bubbles at times around it.

Angelous
01-22-2007, 05:06 AM
you replace your old rubber plug with a $6 new one. Or you can silicone around the edge.

6Banger
02-14-2007, 05:14 AM
nice wirte-up, going to due this when the snow thaws.