Procedure for changing diff fluid?

I'm sure so many of you have changed you diff fluid so many times you could do it with your eyes closed.

Can someone give me a brief overview of what to expect? I've never changed diff fluids before...

TIA!

Not a bad job at all. Place a suitable size receptacle under the diff and remove all of the cover bolts except the top one or two (loosen but do not remove). Seperate the cover from the diff and let the fluid drain. You may have to pry the cover with a thin bladed tool (putty knife) or tap it around with a soft-faced hammer gently to get it to seperate. When it does, pull the bottom away from the diff and let her drain. The two top bolts will keep the cover from accidentally popping off and covering you with diff fluid. Once drained, pull the cover off completely and clean the inside, and the mating surfaces of the cover and diff. You can spray the inside of the diff with brake cleaner to get it really clean if you want. To reinstall, make sure the mating surfaces are clean and dry. You can use a paper gasket, or plain RTV (I prefer RTV blue..) Run a 1/8" bead of RTV around the diff cover, going inside of the bolt holes when you come to them. Let it tack up for about 10 minutes, then press it up to the diff and reinstall the bolts finger tight. Let it sit for about 5 minutes like that, then torque the bolts to spec in a criss-cross pattern. Remove the fill plug and add new fluid until it starts to seep out of the fill hole. Replace plug and you're done.
HTH,
Jeff

edit -> Learn to like the smell of gear oil. It's quite unique

Jeff's procedure sounds about right.

I've never changed diff fluid on an XJ before but it's got to be easier than a Ford 9" (you have to remove the axles and pop the pumpkin). Something I do with eyes open!

For the rear diff, you might want to raise the front of the truck a little (ramps or 2x4s or an unlevel driveway) to help drainage. Then, simply remove all of the bolts holding the cover in place. More than likely the cover will be stuck in place by the gasket. CAREFULLY pry the cover loose with a putty knife or screwdriver (you don't want to bend the cover) at the bottom of the pumpkin. Have a drain pan ready to catch the old fluid. Allow a sufficient amount of time for all of the old fluid to drain out. This would be a good time to run to the auto parts store for a new diff cover gasket, new gear lubricant and some silicone gasket sealer. Use the putty knife or razor blade to remove the old gasket from the cover. Wipe any remaining fluid drips from the pumpkin and clean both with something that cuts the oil (gas or paint thinner). Apply a thin bead of gasket sealer to the cover and pumpkin. Orient the gasket on the cover and then hold both in place on the pumpkin while you replace the bolts, finger tight. Perhaps someone else can provide a bolt tightening sequence, torque rating and amount of gear oil required. The fill plug should be on the driveshaft side of the diff. I would think the front diff would be a similar procedure.

Best of Luck - Dave.

Thanks guys. Sounds like it's a pretty easy procedure...

Just back the truck over a sewer and let it drain out. Drive it for at least 200 miles to make sure you got it all out.

It's kinda like a colon cleaning............

You are joking, right?


I remember way back in the day, changing oil with my dad and dumping the used oil down the sewer grate in the alley behind the house.....

somewhere down the line we all figured out that wasn't cool.
Jeff

actually i need the oil dump on my neighbor's lawn....

I have a neighbor like that.

What's the best fluid to use when refilling? How is the Mobil1 gear oil?

Mobil 1 synthetic blend gear lube is great stuff, not good in coffee though

Jeff in VA said:

Learn to like the smell of gear oil. It's quite unique

Click to expand...

I've since learned to love it..especially synthetic!!! Oh, and nice job on the instructions.

Jeff in VA said:

Learn to like the smell of gear oil. It's quite unique

Click to expand...

Unless you manage to spill a bottle on your front passenger floor. It warms up pretty nicely and always has that heavy oil smell...

ARRRRGGGGGGGGGGG!! burnt 90-weight is the bane of my existance!

the service manual recommends synthetic 85 w 140 for towing applications... i use valvoline synth blend 85w 140... also make sure you use the limited-slip "additive" if you have a trac-loc unit.. it NEEDS it or your clutches will live a short life..
mike

Sorry to resurrect this ancient post, but I guess it proves I searched. Whoever did the rear diff oil on my xj last used a metric ton of sealant, to the point that it quite literally oozed out of the sides and coated the bolts in their holes. Suffice it to say I can't fit anything at all between the cover and the pumpkin. Anyone have any suggestions for getting the cover off? Pumping the oil out didn't get me anywhere.

Use a utility knife with a clean sharp new blade. Once you get a small groove cut in somewhere (be careful), use the smallest flat blade screwdriver you have to get a purchase point. Work it in in one spot, then insert a larger screwdriver or putty knife. You'll get it, just be patient with it and try not to gouge the mating surface on the diff.

Jeff

I had to use a long thick flathead screw driver and a BFH (big effin hammer) to work my way in there and pry it off.

Look at it this way, once it's off, you'll know what NOT to do....lol

So basically the thinest stiffest sharpest item I can find and a bit of "percussive maintenance. I can handle that, even if it is a little frightening for a semi-newbie to do on his DD.

IMO, there are some spots around the cover better to work from than others. Try accessing it from about the 9 o'clock position (if you're facing it) about mildine of the axletube.

Just becareful that once you finally do get through the "metric ton" of RTV, that the sharp thin "object" doesn't get out of your hand and you accidentally run it into the gears in your differential. No need in damaging them