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Help Changing Rear Differential Fluid

KPPCExplorer

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City, State
Kings Park, New York
Year, Model & Trim Level
2002 XLT V6
I'm looking to change my rear differential fluid. Just did my transfer case fluid with no problem. I know the differential is supposed to be sealed for life, but I do some off roading and definitely submerged it dozens of time. Not to mention I now have almost 145,000 miles and would like to get fresh oil in there.

Now, I see the 3/4 inch drain hole, and there's a plug directly above it that's 3/8, but I don't believe that's the fill plug. I read on the forums that the fill plug is 1/2 inch, but I don't see it on the axle anywhere. It's a little tight in there, so maybe I'm just missing something. I watched the thread on how to change the fluid a dozen times under the differential/transfer case/transmission section, but that was from a older generation explorer and ours look a lot different back there. Does anybody know where the fill plug is on the rear differential? Thanks.
 



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The fill plug is 3/8" and drain is 1". In case you didn't see other posting on fluid change, start with actually loosing the fill plug first. You want to make sure you can put fresh oil in afterwards. After confirming that the fill plug can be removed then drain the diff. Also use some teflon tape on the plugs so you don't get seepage. If yours is a LS don't forget the friction modifier.

It'll take just about 2 quarts.
 






Mine fill plug is 3/8 your on the right one
 






You can also get a little hand pump thing for 10 bucks that will let you stick a small hose into your bottle of gear oil and the other hose into the fill plug hole. Makes it easier than dealing with the tricky angle with the fill hole and trying to tip a bottle up in there.
 






make sure you over fill it a half quart after it starts dripping from the fill plug...
 






You can also get a little hand pump thing for 10 bucks that will let you stick a small hose into your bottle of gear oil and the other hose into the fill plug hole. Makes it easier than dealing with the tricky angle with the fill hole and trying to tip a bottle up in there.

What he said!:)
 






You can also get a little hand pump thing for 10 bucks that will let you stick a small hose into your bottle of gear oil and the other hose into the fill plug hole. Makes it easier than dealing with the tricky angle with the fill hole and trying to tip a bottle up in there.

+2

This will make the job much EASIER and CLEANER!!!
 






>>>>>>>>>>>
Does anybody know where the fill plug is on the rear differential? Thanks.
>>>>>>>>>>>>

The fill plug is the smaller plug hole at the top and the larger, lower plug is for draining the rear diff. There is plenty of room to get the plugs out, approx: 2 inches or so of clearance. The rear diff on my 2005 Explorer uses Mobil One full synthetic 75W-140 gear oil according to the Haynes manual, not sure if yours is the same. The stuff isn't cheap (liquid gold), I paid $18.99 per quart(buy 2) and it should take 1.60 to 1.75 quarts depending on which diff you have. If you do have a Limited Slip differential, add 4 ounces of Friction Modifier as well. It comes in a 7 ounce squeeze tube. A hand pump works good to fill up the diff. If you have an Advance Auto Parts store near you, order all the stuff online and pick it up at the store and use their coupons from Coupon Cabin.com. You can get $20 off a $50 dollar order and your order will come close to that amount for this job. If you need extra elbow or head room under the rear end, remove the spare tire. It's not hard to do.
 






I know how you do it and what you put in, I'm just trying to make sure I got the right fill hole before I go and open it and find out it's not the fill hole and I now can't drive my car. I thought the fill hole was usually on top of the differential, but this one is just over half way up.
I took a picture of my differential. Could somebody confirm if this is correct? Thanks.
explorerz.jpg
 






I know how you do it and what you put in, I'm just trying to make sure I got the right fill hole before I go and open it and find out it's not the fill hole and I now can't drive my car. I thought the fill hole was usually on top of the differential, but this one is just over half way up.
I took a picture of my differential. Could somebody confirm if this is correct? Thanks.
explorerz.jpg

CORRECT!!!

Now get to work:D
 






I most definitely will. Thanks Limited!
 






So what do you use to take that huge plug out? I thought about doing mine but didn't have anything to take it out with.

STU
 












You need to buy a 3/4" socket adapter that will fit on a 1/2" drive ratchet or breaker bar.

DING DING DING, we have a winner!!! :D

This is the same thing I did.
 






>>>>>>>>>>>>>
I thought the fill hole was usually on top of the differential, but this one is just over half way up.
I took a picture of my differential. Could somebody confirm if this is correct? Thanks.>>>>>>>>>>>

If the fill hole was on top of the diff housing, you need a hell fo alot of gear oil to fill it up and that would be overkill. Approx half way up the housing is correct for a diff fill hole, just enough oil to keep half of the gears submerged in oil and well lubricated through the splashing, blender like motion of the gear teeth spinning through the oil as the vehicle moves. You'll see it is an easy job. FYI, I stopped at one of those quick oil change places and was quoted $100 + tax to change out that gear oil in the rear diff. I looked at the guy and said you must be $hitting me! I was thinking more like $39 till he told me about the "liquid gold" oil it needed. Doing it yourself and using the discount coupons I mentioned if you can, you'll save yourself approx. $65 + the tax "differential".
 






Well I did it today and it was very easy. Cost me $38 for 2 quarts of oil and $7 for a 1/2 inch to 3/4 inch drive adapter. Used a suction gun to put the new fluid in and it's good as new. The old fluid was definitely dirty and needed to be changed. Thanks for the help guys.
 






>>>>>>>>>>>>>>>>
Well I did it today and it was very easy. Cost me $38 for 2 quarts of oil and $7 for a 1/2 inch to 3/4 inch drive adapter. Used a suction gun to put the new fluid in and it's good as new. The old fluid was definitely dirty and needed to be changed. Thanks for the help guys.
>>>>>>>>>>>>>>>>>>

Glad to hear it went well for you. Just think, 5 quarts of that "liquid gold" gear oil you just bought, costs the same as a 55 gallon drum of crude oil.
 






Well I did it today and it was very easy. Cost me $38 for 2 quarts of oil and $7 for a 1/2 inch to 3/4 inch drive adapter. Used a suction gun to put the new fluid in and it's good as new. The old fluid was definitely dirty and needed to be changed. Thanks for the help guys.

I did my front and rear diffs at 122k, the rear was black and the front was even blacker and sludgy. Pretty sure diff oil needs to be changed more often than that. For some reason a 60k or 75k interval rings a bell?

For anyone else looking for ideas, I opted for a 3/4" drive breaker bar for $20 at a ranch supply store. My 1/2" bar bends at the joint quite a bit at 200ftlbs (changed a AWD/4WD front wheel hub yet?) so it couldn't hurt to have a much thicker bar and an adapter down to 1/2" for future projects :p The 3/4" plug on the rear diff wasn't that hard to remove. Haynes says 25ftlbs for the "check/fill plug" and nothing for the drain plug. Also, I drained into a normal oil changing pan and used a hand pump to pump new fluid. Dumped the LS friction modifier into the first bottle and shook it up then resumed pumping.
 






Has anyone pulled the rear diff cover off to drain the fluid/clean out and inspect the gears etc. like you would do on a normal Dana 44 etc? I need to change my fluid, but after driving at highway speeds for awhile, i am getting a very distinct grinding feeling while turning as if all the oil has spun off the gears, but after sitting/slow speed driving around town it returns to normal. I want to pull the cover off and check for metal shavings etc. when i change the fluid but am wondering if its a major PITA...
 



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I havent done it but it kinda looks like itd be a pain, the top bolts are hidden by a cover type deal
 






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