Hello all,

I did some googling and this is a very common issue. The easiest place to start is by checking the differential fluid and adding to it. I just want to clarify a few things before I go forward with doing this.

First, the few threads I came across said the noise goes away immediately when shifting back into 2wd regardless of speed. My noise stays until I come to a complete stop. For example, I'm driving 40mph in 4wd. I shift back to 2wd while still going 40. Even if I slow down to say 20 then back up to 40, the noise remains. Once I come to a complete stop, the noise doesn't come back once I start moving again as long as I stay in 2wd. I can confirm the 4wd is disengaging when I move the lever back to 2wd.

So now onto the fluid check. My understanding is there's a little plug somewhere on the differential. Do I have to actually change the fluid or just top it off? As far as I know it's never been done. What kind of fluid do I use? Do I just fill it up until fluid starts running out of the fill plug?

I have a 96 XJ, 4.0L, automatic, and a 231 TC.

Thanks

 

Loosen all the bolts about 1 turn but take the bottom (4?) 5 maybe, bolts completely out.
Then take a flat head screw driver and carefully wedge it between the cover and the diff housing. Have a bucket under the diff. The fluid will drain out the bottom and then you can pull the cover off completely. Check fluid for metal shavings and inspect the gears.
Once this has been done to seal up the cover again scrape all old material from the surfaces of both housing and cover. Then, put a continuous bead of black rtv circling all bolt holes on to the diff housing.
Place cover on and tighten all bolts in a star pattern. The. To fill, get some diff oil(I just use 80-90 for all my diffs) and take out the plug on the diff. Fill until it starts running out of the differential. Put plug back in and your good to go

 

thanks. I'm hoping to get to it soon. With all the snow we've been getting the 4wd has been getting a lot of use. I don't want to break anything in the mean time.

 

have you checked the u-joints on the axle and drive shaft? they go bad and will make noise when you do. there should be no play in them. or if you see a bright orange rusty looking dust around them thats also a sign of play/bad u-joints.

 

i haven't but when I get under there i'll take a look. to check for play, do i try and move the axle? how exactly does one check to see if they're loose/worn?

 

well the first check is to try and rotate the axle while holding the wheel from spinning. turn it back and forth and see if you feel or see play in the joints. if you dont have anything there then you can take a pry bar stick it into the joint and pry on it a little bit and see if there is some play there. up down then back and forth. rotate the axle a little bit and check again. until you are confident there is no play. also if it's dry enough that note earlier about the orange rust colored powder like substance around the joints will be a dead give away that one of the bearings in the joint is bad.

 

thanks for a detailed explanation. i'm hoping i'll get to take a look next weekend. i'll update once i do.

 

I finally got around to doing the fluid in my front dif. Although the oil definitely needed changing (it was pretty runny), the noise I was hearing is still there. I had someone else drive it as I ran next to it (at low speeds of course lol) with the 4 wheel engaged and the sound seems to actually be coming from the passenger side tire or something in that general area and not the differential as I originally thought. There's a clunk that occurs after disengaging 4wd and coming to a complete stop. I had a buddy drive at about 15 mph in 4wd, disengage 4wd while still moving at 15 mph (the noise I mentioned previously is still present), then come to a complete stop and that's when I heard something go clunk. After accelerating from the stop (in 2wd), there's no more noise and no more clunking. We did it a few times to make sure it wasn't a fluke. It happened every time. If in 2wd or 4wd and come to a complete stop, no clunk. If in 2wd, engage 4wd, then come to a complete stop, no clunk. If in 4wd, shift to 2wd, and come to a complete stop, CLUNK!

I have no idea what this could be :\ Any help would be greatly appreciated.

 

what was the conditions of the u-joints. what you are describing all sounds like u-joints they make noise when there is a load on them, like when they are driving the front wheels with 4wd engaged.

 

the drive shaft u-joints look to be in good shape, however, i didn't realize the front tires have two u-joints on the ends of the axle. i think the one on the passenger side is going. when running my finger over it some orangish powder came off. i need to jack it up and pull the tire to get a better look but i'm thinking i found the culprit.

i came across this video ( ) where the dude really gives some detail on how to check all the u-joints. for the googler's out there, after I get a chance to do some more investigating i'll follow up.

i don't have a press unfortunately to replace them but i'll worry about that when the time comes.

 

You can do most u joints with a socket, hammer and a cinder block

 

hammer and cinderblock does the trick. try and look for a video that doesn't involve the press i'm sure they are out there