Diff Fluid Change

Cableguy said:

2003KJ said:

Really easy to do youself if you've got a few hours to kill, and yes the rear end is a pain in the ****!

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So I don't get why everyone seems to have a problem with the rear end. It's like 8 bolts, and some RTV. Unless you didn't jack it up, that would make it more difficult, but other than that...

I dunno, mine seemed easy, just time consuming wating for the rtv to cure properly.

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Let me rephrase that: Compared to the front, it was a pain in the ****. But overall, yes it is very very easy to do, and you can save yourself alot of $$$$. I almost took it to a shop to get it done, untill several on here and on LOST talked me into doing it myself.

2003KJ said:

Let me rephrase that: Compared to the front, it was a pain in the ****. But overall, yes it is very very easy to do, and you can save yourself alot of $$$$. I almost took it to a shop to get it done, untill several on here and on LOST talked me into doing it myself.

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It's getting really close for me to do that as well. Do you suggest jacking it up? Also, is it just standard tools (some wrenches, etc...)

I'm gonna look under the Jeep when the ground dries up this week and I can easily cancel my weekend appointment. I'm not mechanically handicap so if I get myself under there and take a look at what needs to be done I'm sure I can do it. Even more so that everyone is saying that it is a simple procedure.

blckkj said:

2003KJ said:

Let me rephrase that: Compared to the front, it was a pain in the ****. But overall, yes it is very very easy to do, and you can save yourself alot of $$$$. I almost took it to a shop to get it done, untill several on here and on LOST talked me into doing it myself.

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It's getting really close for me to do that as well. Do you suggest jacking it up? Also, is it just standard tools (some wrenches, etc...)

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Simple is an understatement. Remove the bolts holding the diff cover, use a screwdriver/prybar to pop the cover off, let fluid drain, scrape old sealant off, put new RTV (i used red, can be had from wal-mart), bolt cover on, let rtv cure, pour in oil (+Friction modifier if you have a trac-loc). Wax on, wax off.

If you jack up the rear of the body and let the suspension uncompress the diff will drop a few inches making it way easier to access. A good pair of jackstands comes in handy for this.

Awesome! Thanks for very informative post.

Yes I do recommend jacking it up. I had access to a lift at the time (pays to have friends in the mechanic business who own their own shops with the cool equipment) and lifted it up enough to get a good 10 gallon bucket under there. You can probably use a smaller container, but I wanted something with a wide opening as to reduce the ammount of oil that hit the floor.

One key thing you want to remember, when you pull the cover off, make sure you get ALL the old RTV off the cover AND the edge of the differential. If you don't get it as clean as humanly possible, the new stuff will not set properly.

Simple is an understatement. Remove the bolts holding the diff cover, use a screwdriver/prybar to pop the cover off, let fluid drain, scrape old sealant off, put new RTV (i used red, can be had from wal-mart), bolt cover on, let rtv cure, pour in oil (+Friction modifier if you have a trac-loc). Wax on, wax off.

If you jack up the rear of the body and let the suspension uncompress the diff will drop a few inches making it way easier to access. A good pair of jackstands comes in handy for this.

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That's how I did mine with the Red from Wally World.
Please don't get under any vehicle supported by a jack alone!

The rear diff. is simple in concept, but actually doing it is much harder. It's NOT a 10 minute job. And these KJs are harder than pickup trucks because the fuel tank is in the way. Good tip on jacking up the rear of the Jeep for more access to the diff!

Anyway...the hardest parts are scraping off the old sealant and filling the diff. The old sealant can be a royal pain to scrape off. With a putty knife it takes forever. I used my cordless Dremel tool to sand it off last time I did it...made the job go faster. But it's still a pain. And then once you reseal the inspection cover and try to lift the 1-quart bottle up there to refill it you'll discover a whole new nightmare. This job will wear you out. I used a small piece of hose on the nipple of the gear oil bottle. This allowed me to turn the bottle more upright and squeeze more oil into the fill hole. If you don't do this the gas tank will be in the way and make it a pain to squeeze the oil into the diff. Unless you have one of those fancy mechanical pumps...

LibertyCRD said:

And then once you reseal the inspection cover and try to lift the 1-quart bottle up there to refill it you'll discover a whole new nightmare. This job will wear you out. I used a small piece of hose on the nipple of the gear oil bottle. This allowed me to turn the bottle more upright and squeeze more oil into the fill hole. If you don't do this the gas tank will be in the way and make it a pain to squeeze the oil into the diff. Unless you have one of those fancy mechanical pumps...

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GOOD POINT! =D>

Simple = Yes. Time Consuming = VERY

Handy Tip Number 2: Go to wally world/auto parts store, and invest the 5 bucks in a cheap gear oil pump that threads right into the top of a quart bottle. It is WORTH EVERY DARN PENNY!
<a href ="http://www.lubeoilsales.com/products/amsoil_hand_pumps.htm">Example</a>

I actually bought 2 from wally world, used one to fill my diffs, and one to fill the t-case, just because it was easier. Best 10 bucks i've ever spent. Even throwing that, the rtv, and the oil into the cost, it was still cheaper than having the dealer do it.

All this information is great. So what is the exact fluids that I need to buy to insure that I have all fluids ready. Is there a brand over another brand, etc...?

I don't do much off-roading at all (maybe a couple times a year) but I do use 4x4 during the winter/snow months (which is hopefully now long gone).

Could you use a Pella or similar to suck the old fluid out through the drain hole which would not require removal of the cover. Anyone tried this?

I used the reccomended weights for the front and the back (75W90 in the back, and I don't recall the front off the top of my head). They're listed in your owners manual.

The book DOES however, recommend synthetic for the front....which will raise the price somewhat.

The brand I used was Valvoline.

Thanks again for the info

sdean said:

Could you use a Pella or similar to suck the old fluid out through the drain hole which would not require removal of the cover. Anyone tried this?

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No drain hole in the rear diff. just the filler plug. I use the opportunity to take a good look at the gearing and wear patterns inside the diff, since i've got the cover off anyways. but i'm "**** retentive" according to my wife. :-k

Front diff has a drain, and is simple to change.

sdean said:

Could you use a Pella or similar to suck the old fluid out through the drain hole which would not require removal of the cover. Anyone tried this?

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Yes. Using the previously mentioned inexpensive lube pump, you could remove probably close to 90% of the old oil without removing, cleaning, and resealing the cover.

Check gear oil requirements

Hey all, regarding gear oil specs, my 2005 KJ manaul specifies 75w140 Synthetic for both front and rear diffs along with a friction modifier for Trac-Loc. Being an old school hot rod guy I have all the tools and tricks for performing the task. Found both relatively easy. I would be hard pressed to pay someone to do what I can do for myself. Really easy to do when all four wheels are off of the ground and the rear suspension is permitted to hang. I cleaned the old RTV off with a gasket scraper and a brass brush in my die grinder. When "sanding" off the old gasket material be certain not to remove excess material from the gasket mating surface on the cover or distorting the gasket mating surface on the diff. Best use a scraper made from a non-ferrous metal.

I changed mine at 12.5K as per Jeep's recommendations. I used Valvoline Synthetic 75W-140 in both axles, and it is expensive. I paid $71 for 4 quarts with a small tube of silicone gasket maker for the rear axle. I removed the rear cover so to be certain I got all the metal from the axle breaking in from brand new. I did not find any sign of metal, it was basically clean mineral based axle oil. I know Jeep says change it every 12.5K miles, but i wonder if anyone has tried the synthetic and ran it farther? Jeep says use synthetic in the rear if you tow; I put synthetic in both from and rear figuring it is better protection. Jeep says use the basic mineral oil in the front axle. I have almost 25K now so it is time for the second change.

Silver Streak
`05 CRD Sport

From the Factory Service Manual:

FRONT AXLE
² 186FIA (Model 30) - Mopart Lubricant 80W-90

REAR AXLE
² 8 1/4 - Mopart Gear Lubricant 75W-90 (Trailer
Towing - Mopart Synthentic Gear Lubricant 75W-140
NOTE: Trac-lokT equipped axles require 118 ml (4
ounces) of Limited Slip Additive be added to the
lubricant.

alljeep said:

Not only that, but if you have a CRD, the user manual states mandatory changes at 12,000 mile intervals! My question is, what has changed over the past few years to make a manufacturer go to this extreme?

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Maybe all that torque from the 2.8L CRD is too tough on the Corporate 8.25" Rear.

Greg