Front Diff and Transfer Case Oil Change Howto

oh i forgot it ran with chains and not gears so change it anyways "/ looks really clean but it is passed the recommendation period 30k miles

 

I rarely see a T-case with nasty oil in it, they seem to run cleaner than gears.

Howard

 

Thanks for this, I'll be changing my fluids soon..

 

I had the same. T-case looked new, clear and amber colored. Front and rear diffs looked like old motor oil, opaque and black.
I had about 65k and four years on mine at the time.

 

wow haha ya i didn't know how long it had the same oil so i just did it, sense ive been hitting the trails every weekend i didn't want to risk damaging my case, now i just need my front diff but i think the plugs are stripped "/ so i need to take off the front diff to work on it

 

this job is easy..but it makes up for it in terms of mess..i think i burned thru 5 pairs of nitrile gloves..

and i still smell it. i used 6 qts for front, rear, and transfer case..FYI..i sucked air at the handpump, just as the oil started to trickle at the rear. verified with a flashlight..oil at the right level..

i am not effing with this messy job until just over 100k miles.

 

Replacing with synthetic soon. Hope i don't screw it up. Thanks for the How to

 

Great write-up.

I notice that a lot of people are complaining about the mess one or both of the differentials create by squirting out when you open the bottom plug.

To avoid this, after you have removed the fill plug, thread it back in by hand before removing the drain plug. Otherwise air will pull through the fill plug allowing the differential to drain much faster. After you have the drain flowing into a container, reopen the fill plug.

=No mess.

 

That's what I did and you're right, no mess. I should have added that comment, thanks. I might add that you only need to thread it in a turn or two. Just enough to hold. Then, once it is flowing, slowly back the bolt out as the 'burp' of air can result in the same effect at the drain hole. By the time you take out the drain plug, put it down, and then back out the fill plug, enough fluid should have drained to minimize any gushing out the drain hole.

 

Well I bought my truck with 40k, currently at 105k, never touched the rear diff or front or t-case. Bought all the oil and additive. Went to take the fill plug off and noticed it was a bit stripped but still had somethin to grab onto. So I ended up rounding the damn thing over completely. Thats when I got a good size bolt and welded a nut to it and then welded that to the original fill plug.



Here is the Bolt/nut welded to the fill plug




I noticed that the drain plug did not have a washer but the fill did. The rear diff fluid was really bad. Smelled horrible too. The magnet hardly had anything stuck to it. The other magnet was completely BARE. The front diff and t case fluids looked brand new as well.

 

"The rear diff fluid was really bad. Smelled horrible too. The magnet hardly had anything stuck to it. The other magnet was completely BARE. The front diff and t case fluids looked brand new as well.

X2. The rear looked horrible so that obviously should be changed. It as grey and smelly - grey from water or moisture ? Raise the breather cure it ? The front diff and t case fluids looked brand new - would that mean no real reason to change them ?

 

Diff breather mod is my next project. I think it will help, and yes water will get in and discolor the oil like if you get water in your motor oil.

I did not change the front diff or t case because it looked as clean as the new oil I put into the rear diff.

 

I'm thinking of skipping them 2. Wonder what others think - others with more knowledge then me.

 

Thinking of doing this with M1 75w90 (dont have the LSD) but I'm wondering, do I have to do the front, rear, and T case all at the same time? Do the oils end up mixing somehow?

 

No and no.

 

i changed my diff fluids out at 15k miles and it was really nasty and smelly in the rear diff, the transmission, transfer case, and front diff were fine. I did the diff. breather mod to the rear, changed out the fluids at 45k miles and the rear was completely clean and fine as were all the other fluids so next change is at 75k miles (plus i am using all synthetics)

 

Do you think the breather mod had anything to do with the oil's good condition at the second change? I'm thinking of doing the mod as well.

 

I just changed my rear diff at 59,000. The oil was like new - nice clear honey color and no smell at all. I had changed it at 28,000 and it was nasty - grey and smelly.. The transmission, transfer case and front diff were fine. Since they were fine at 28,000 on conventional oil and I now have syn I didn't change them at 59,000 - is there any reason too ? The rear diff was nasty on conventional oil but clean on synthetic.

 

I just removed my breather cleaned it with PB Blaster and put it back. I switched from conventional to synthetic. On conventional it was nasty, grey and smelly on synthetic it was clean, clear and the only smell was the same as synthetic right out of the bottle.

 

Just did my rear diff and it looked new. At least I know there is good synth in there now. Going to do the front and Tcase this weekend.
Very easy job. Nice write-up by the way.