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Unread 05-02-2013, 05:30 AM   #1
toozie21
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Advice needed on differential fluid replacement

So I just realized that I need to change the front/rear differential fluid in my '04 as it is WAY overdue. I have never done this in any car, so I am a bit hesitant, but I was hoping someone could look over my plan and let me know if it seems reasonable.

For the front, it seems to be a lot like a oil change. Undo the bolt in the front underneath, open the the fill cap and let it drain. When done, replace the bolt, add the oil, and replace the fill cap. About right?

As for the rear, that one seems a little tricker. Seems like I need to unbolt the plate on the back of the differential, then take a screwdriver and pry it open (because of the RTV). After making a mess and draining out the fluid, I need to wipe out the plate and the inside of the differential to clean it up some (I assume just use a dry cloth?). Then clean the RTV off the plate and housing (just scrape it?), apply new RTV (just smear it on?), and rebolt into place. Once in place, pop the little access plug off (just use a screwdriver?), and pour the oil into the differential until it is within a 1/2" of the plug hole (is there a better way to do that?). Replace the plug and drive off.

Am I close? All seems reasonable, I just didn't want to get halfway into it and realize I hadn't prepared for something.....

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Unread 05-02-2013, 06:19 AM   #2
TwoBobsKJ
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Sounds good - you've done your research!

Couple of pointers:

* Remove the fill plug FIRST on the front diff. May not happen to you but nothing worse than removing the drain plug then not being able to get the fill plug out. Same goes for changing engine oil and transfer case fluid. (This tip applies to ANY vehicle - this isn't Jeep-specific.)

* The front diff fill plug uses a 3/8" ratchet extension; the drain plug is a 10mm Allen wrench

* Once you've removed the rear diff cover use a spray can of brake cleaner on the inside of the diff. Spray all the gears and bearings till they're nice and clean and give a good spray to the magnet on the bottom so there's enough fluid to wash away any metal particles that are attracted to the magnet. (If there are a few tiny metal particles attached to the magnet no need to worry - that's what the magnet is there for.)

* Fill both diffs with oil until the fluid just starts to drip out of the fill plug. Use 85W-140 standard gear oil in both diffs. No need to spend the extra on synthetic. I know the manual calls for synthetic but folks on here with far more knowledge of the correct oils for differentials always recommend standard dyno oil instead of synth.

You should also change the fluid in your transfer case. It's easier than the diffs and just as important. It uses just under two quarts of ATF+4 transmission fluid.

Let us know how your first diff project turns out!

Bob

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Unread 05-02-2013, 09:16 AM   #3
toozie21
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Quote:
Originally Posted by TwoBobsKJ View Post
Sounds good - you've done your research!

Couple of pointers:

* Remove the fill plug FIRST on the front diff. May not happen to you but nothing worse than removing the drain plug then not being able to get the fill plug out. Same goes for changing engine oil and transfer case fluid. (This tip applies to ANY vehicle - this isn't Jeep-specific.)
Thanks, I tried to look around before posting. Great advice!! That was the sort of tip I was looking for!

Quote:
* The front diff fill plug uses a 3/8" ratchet extension; the drain plug is a 10mm Allen wrench
Ah, so the fill plug is bolt like? I will have to go look for it. I just assumed it was something like the oil cap.

Quote:
* Once you've removed the rear diff cover use a spray can of brake cleaner on the inside of the diff. Spray all the gears and bearings till they're nice and clean and give a good spray to the magnet on the bottom so there's enough fluid to wash away any metal particles that are attracted to the magnet. (If there are a few tiny metal particles attached to the magnet no need to worry - that's what the magnet is there for.)
OK, so spray, let it sit, then wipe it all out? Or do you mean to just spray it and let the spray run out of the diff?

Quote:
* Fill both diffs with oil until the fluid just starts to drip out of the fill plug. Use 85W-140 standard gear oil in both diffs. No need to spend the extra on synthetic. I know the manual calls for synthetic but folks on here with far more knowledge of the correct oils for differentials always recommend standard dyno oil instead of synth.
Agreed. Everywhere I looked it seemed like the pros were recommending regular, which is fine by me (sounds like the synthetic was noticeably more).

Quote:
You should also change the fluid in your transfer case. It's easier than the diffs and just as important. It uses just under two quarts of ATF+4 transmission fluid.
OK, sounds good. I haven't done that either, so I am SURE it is overdo. Thank you for the heads us.

Quote:
Let us know how your first diff project turns out!
Will do! Thanks for the help. Definitely seems doable, so I am looking forward to getting a little dirty. Any advice/words of wisdom on the RTV?
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Unread 05-02-2013, 09:26 AM   #4
TheBlueKJ
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Quote:
Originally Posted by toozie21 View Post
Will do! Thanks for the help. Definitely seems doable, so I am looking forward to getting a little dirty. Any advice/words of wisdom on the RTV?
Go to your local parts store and there should be a section of different RTVs for different applications. There should be one for gears with a differential on the side of the packaging (if its permatex brand). That's the type you need.

And if you have an LSD you'll need the friction modifier as well for the rear. One simple way of testing to see if you have one is to jack up the rear of the vehicle with it in neutral and spin the wheels. If one spins freely and the other doesn't it's an open diff. If both wheels spin simultaniously you have an LSD and need the friction modifier.
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Unread 05-02-2013, 09:43 AM   #5
tjkj2002
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Quote:
Originally Posted by toozie21 View Post
Any advice/words of wisdom on the RTV?
I'd recommend Permatex Ultra Gray or there gear oil specific RTV.Apply a 3/16" bead all around the cover going around the inside of each bolt hole,then apply a bead around the outside of the bolts holes.Let stand for about 5-10mins before putting cover back on,then only tighten until you start to see the RTV sqeeze out around the cover,wait another 5-10mins then fully tighten the cover bolts.Wait 30-45mins then refill with gear oil.

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Unread 05-02-2013, 10:26 AM   #6
Jeepguy4276
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While you have the cover off you could clean the outdode up and give it a coat of paint. Not needed, but why not? I slways clean and paint (if it can/should be) parts when i have them off. It's quick to do and keeps things clean.
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Unread 05-03-2013, 06:13 AM   #7
TwoBobsKJ
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Quote:
Originally Posted by toozie21 View Post
Ah, so the fill plug is bolt like? I will have to go look for it. I just assumed it was something like the oil cap.
It is like the side of a socket in which you place the ratchet. It doesn't have a bolt head but is a 3/8" female plug.


Quote:
OK, so spray, let it sit, then wipe it all out? Or do you mean to just spray it and let the spray run out of the diff?
Spray the brake cleaner all around the inside of the diff and let it drain out. I will evaporate quickly so as you're spraying also wipe out the bottom of the diff around the magnet.

This is good maintenance to be doing - have fun!

Bob
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Unread 05-03-2013, 08:50 AM   #8
BobFromCO
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All good info presented here, and I've done diff fluid changes with no problem when doing them just as described in the previous posts.
When you do the transfer case fluid you REALLY want to follow the advise regarding removing the FILL plug first. They are notorious for being difficult to remove. When I did mine, I ended up buggering it up pretty bad and had to take it to a shop to finish it. It's a plug that sits flush with the case and if the socket gets rounded out, its almost impossible to remove. We replaced it with a plug that is more like what you find on a oil pan and don't anticipate any more problems.
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Unread 05-03-2013, 11:29 AM   #9
toozie21
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You guys rock, thanks for all the advice and pics, I am starting to feel pretty good about this being successful!

One more question I had though. I've seen that people say to jack up the jeep, and put jack stands on the frame right by the wheels so that the back end (for front end) drops a little. I assume that we want the 1cm drop since people talk about the oil in the end being 1cm before the drain plug? Would rolling it up on ramps slightly work just as well (I guess jacking standing it gives you some more wiggleroom to get to the rear though)?
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Unread 05-03-2013, 03:00 PM   #10
BobFromCO
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Since the front diff has the drain plug right on the bottom, I've not found it necessary to jack the front up, but the rear is a different story. Jacking up the rear and putting jacks under the frame allows the rear to drop down from behind the gas tank and makes it easier to access the diff cover. Since you're removing the cover and wiping it out, it doesn't make much difference as far as getting all the old fluid out. So, jack it up, let the rear axle drop a little and you'll have easy access to the rear diff bolts.
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Unread 05-04-2013, 08:36 AM   #11
0uTkAsT
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Great info here. Does anyone have a link to Liberty maintenance schedules? I'm curious what intervals the different fluids should be changed / flushed at? Not just diffs and transfer case but the tranny, coolant, brakes, etc.
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Unread 05-04-2013, 08:50 AM   #12
TheBlueKJ
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Quote:
Originally Posted by 0uTkAsT View Post
Great info here. Does anyone have a link to Liberty maintenance schedules? I'm curious what intervals the different fluids should be changed / flushed at? Not just diffs and transfer case but the tranny, coolant, brakes, etc.
Tranny-30k
Brakes-every year
Diffs-15k
Tcase-30k
Coolant-100k
Oil-3k

If I left anything out feel free to add on to it
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Unread 05-04-2013, 06:46 PM   #13
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Quote:
Originally Posted by TheBlueKJ View Post
Tranny-30k
Brakes-every year
Diffs-15k
Tcase-30k
Coolant-100k
Oil-3k

If I left anything out feel free to add on to it
These are very conservative intervals. I always did between 5K and 6K on an oil change using fully synthetic oil. As for brakes, replace your pads/rotors as they are required. Anything other than that is a bit of a waste however to each his own. It is also important to inspect the condition of your fluids rather than simply flushing because you you went 15K miles.
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Unread 05-04-2013, 07:12 PM   #14
tjkj2002
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Originally Posted by Trombino View Post
These are very conservative intervals. I always did between 5K and 6K on an oil change using fully synthetic oil. As for brakes, replace your pads/rotors as they are required. Anything other than that is a bit of a waste however to each his own. It is also important to inspect the condition of your fluids rather than simply flushing because you you went 15K miles.
Syn gear oils require sooner OCI's then dino gear oil,this applies to gear oil only.Can't check the condition of the trans or t-case fluid as ATF+4 can not be judged by color or smell since it's dyed red.Vrake fluid and PS fluid are the two most neglected fluids in your vehicle and one is very important and with alot of aluminum used and ABS(if you have it) the fluid condition goes down hill very fast.Water is not really a problem with brake fluid these days,it's the copper content that shows how much corrosion is in the system.
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Unread 05-05-2013, 07:39 AM   #15
TheBlueKJ
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Quote:
Originally Posted by Trombino View Post
These are very conservative intervals. I always did between 5K and 6K on an oil change using fully synthetic oil. As for brakes, replace your pads/rotors as they are required. Anything other than that is a bit of a waste however to each his own. It is also important to inspect the condition of your fluids rather than simply flushing because you you went 15K miles.
I was talking about the brake fluid not the rotors and pads. And I almost forgot about the PS fluid
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