Differential fluid change questions

Jeep4me99 · **Posted:** Sun Feb 18, 2007 10:04 pm

I changed the rear diff fluid for this first time today (53k). Pretty easy job, removing the old gasket was the toughest part imo. yeah it was way overdue, but i have some questions regarding the change.

1.the fluid was black....nasty black...is that because i waited so long to change??? should it not be that color when changing?

2. at the bottom of the pumpkin is a little plate..i'm assuming that is the magnet to collect debris. It was cover in some pretty thick silverish sludge...is that normal, bad, or just ok???

3. on the front diff, I couldnt get the refill plug undone (good thing i checked before draining). Any tips on how to get it loose??

LiLredLibby · **Posted:** Sun Feb 18, 2007 10:27 pm

Jeep4me99 wrote:

I changed the rear diff fluid for this first time today (53k). Pretty easy job, removing the old gasket was the toughest part imo. yeah it was way overdue, but i have some questions regarding the change.

1.the fluid was black....nasty black...is that because i waited so long to change??? should it not be that color when changing?

2. at the bottom of the pumpkin is a little plate..i'm assuming that is the magnet to collect debris. It was cover in some pretty thick silverish sludge...is that normal, bad, or just ok???

3. on the front diff, I couldnt get the refill plug undone (good thing i checked before draining). Any tips on how to get it loose??

Is it hex head,allen,3/8 rachet hole or what?The black fluid and silver sludge are signs of wear,can't say it's normal,but I would'nt worry much until you start hearing unusuall noises.

Jeep4me99 · **Posted:** Sun Feb 18, 2007 10:30 pm

3/8 rachet on the top towards the front of the KJ

LiLredLibby · **Posted:** Sun Feb 18, 2007 10:34 pm

Jeep4me99 wrote:

3/8 rachet on the top towards the front of the KJ

If it's not wollered out,You should be able to insert the rachet,and maybe a cheater pipe to remove.

W3CSX · **Posted:** Mon Feb 19, 2007 12:05 am

The first time I changed my front diff. The plug was on very tight. It just needs a little elbow grease.

alljeep · **Posted:** Mon Feb 19, 2007 12:18 am

W3CSX wrote:

The first time I changed my front diff. The plug was on very tight. It just needs a little elbow grease.

Mine was so loose that I could almost remove it with just my finger tip and a little pressure to turn it. Strange...

Jeep4me99 · **Posted:** Mon Feb 19, 2007 1:43 pm

so no advice as to the sludge on the bottom??

kjfishman · **Posted:** Mon Feb 19, 2007 2:17 pm

Jeep4me99 wrote:

so no advice as to the sludge on the bottom??

I kept my last 2 Jeep Cherokee's around 100k without changing the axle fluids and worked fine. You did the right thing changing it but I wouldn't worry about the old fluid condition.

RFCRD · **Posted:** Mon Feb 19, 2007 3:01 pm

Jeep4me99 wrote:

so no advice as to the sludge on the bottom??

With the rear diff cover removed, spray the guts with solvent and wipe it clean (make sure you clean the magnet on the bottom of the diff housing). Wouldn't worry about small amounts of sludge as long as it is cleaned during the fluid change. If you have a lot of sludge, clean it out the best you can and refill with clean fluid. Then puts some miles on it and follow-up shortly with another fluid change to flush the rest of the sludge.

Edwin · **Posted:** Mon Feb 19, 2007 6:05 pm

Jeep4me99 wrote:

2. at the bottom of the pumpkin is a little plate..i'm assuming that is the magnet to collect debris. It was cover in some pretty thick silverish sludge...is that normal, bad, or just ok??

Mine was the same way and it's been changed twice in 67,000 miles. I just changed it last weekend, for the second time, when I put my powertrax in.
Do you tow alot?

Jeep4me99 · **Posted:** Mon Feb 19, 2007 6:34 pm

Edwin wrote:

Jeep4me99 wrote:

2. at the bottom of the pumpkin is a little plate..i'm assuming that is the magnet to collect debris. It was cover in some pretty thick silverish sludge...is that normal, bad, or just ok??

Mine was the same way and it's been changed twice in 67,000 miles. I just changed it last weekend, for the second time, when I put my powertrax in.
Do you tow alot?

nope, 0 towing, but I go through a lot of water when wheeling, thought maybe some of the nasty water might have got in and contributed to the dark fluid color

Edwin · **Posted:** Mon Feb 19, 2007 9:58 pm

The reason I asked is because up until a few months ago, I've been towin very heavy loads at least 3,000 lbs. So, I think yer diff fluid is probably normal. You wheel alot and I tow alot. Mine was very black too.
Oh, and the 1st time I changed it, I did'nt pull the cover. I pumped it out and put new in, so I never cleaned it goot the 1st time. I did not know there was a magnet in there. I've never seen a diff with one in it.

sleeve84028 · **Posted:** Mon Feb 19, 2007 10:06 pm

If water had gotten into the rear diff, the fluid would have been a frothy, milky color not the blackish sludge that you described in your post.. It was probably just dirty.

RFCRD · **Posted:** Mon Feb 19, 2007 10:23 pm

Edwin wrote:

The reason I asked is because up until a few months ago, I've been towin very heavy loads at least 3,000 lbs. So, I think yer diff fluid is probably normal. You wheel alot and I tow alot. Mine was very black too.
Oh, and the 1st time I changed it, I did'nt pull the cover. I pumped it out and put new in, so I never cleaned it goot the 1st time. I did not know there was a magnet in there. I've never seen a diff with one in it.

I crawled under mine to install a hitch/receiver and happened to touch the axle. Was surprised how hot it gets under normal driving. One of the reasons I used full synthetic fluid and got a PML cover as it's cast aluminum with cooling fins and holds some extra fluid. That's a relatively small diff asked to do the same towing job as many 1/2 ton pick-ups. It will need all the help it can get to stay together.

Differential fluid change questions

Who is online