• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Frothy differential oil

alex22

alex22

NAXJA Forum User
Location
CT: waterbury area
This is what I'm working on.
frothydiffrt8.jpg


notice the froth line just above the two lower carrier bearing cap bolts. The oil drain pan has some froth in it too. I pulled the cover while the oil was still warm after a 20 min drive home from school and found this.
The axle: 8.8 with reused stock 3.73 gears, all new bearings, super88, and a limited slip. I had 3 quarts of Valvoline 85w140 with some limited slip additive. The XJ has 4.5 inches of lift and 31 inch tires.

My question, first of all, is that froth bad, if so would you say its caused by too much oil or not enough oil?

~Alex
 
You probably had water/muddy water in the differential. If the engine oil looks that way too....you might have issues. Drain it and flush an extra quart through it.
 
The front dif on my Chev used to do that, I switched to Red Line and it stopped. Mine would occasionally spew out of the breather tube. It usually happened during high speed runs, with the front not in use.
Like mentioned, water can also make it look like dirty whipped milk.
 
I'm pretty sure its not water, I work in an automotive machine shop so I've seen lots of milkshakes come out of oil pans. That oil has only been in there for two weeks, the last last time i drained it there was some junk in it so I'm going to run the Valvoline for another two weeks to try to flush some more of the stuff out before going back to the Redline.
Do the witness lines on the caps look like the oil level was high enough or too high, I'm getting a slight whine out of it while coasting. and when its cold.

~Alex
 
Nothing but opinion to base this on, but the ring gear has to sling the oil around in there pretty good. As long as there is enough oil to reach the pinion, your likely OK.
How are the carrier ends set up to allow the oil in and out of the axle tubes? On many you have to notch or drill the shims or the oil can migrate into the axle tubes and not drain back like it should.
 
Can you overfill a diff? It's just splash lubrication, so there are no over-pressurization issues to worry about. I used to get a little froth in mine too. I switched to full synthetic and haven't seen any foam since. My diff noise quieted significantly, too.

Froth=accelerated gear wear.
 
8Mud said:
Nothing but opinion to base this on, but the ring gear has to sling the oil around in there pretty good. As long as there is enough oil to reach the pinion, your likely OK.
How are the carrier ends set up to allow the oil in and out of the axle tubes? On many you have to notch or drill the shims or the oil can migrate into the axle tubes and not drain back like it should.
Click to expand...

There is a space for the oil to drain back from the tubes into the center section. Just to get the junk out I'm lifting one side of the tube, then the other to get more of the oil out, one or two more weeks with the cheap stuff to flush the junk out, then back to Redline.

~Alex
 
jester4x4 said:
I dont think there is anything wrong. If you had water in it it would turn a milky color.
Click to expand...

It is milky...

8Mud said:
Nothing but opinion to base this on, but the ring gear has to sling the oil around in there pretty good. As long as there is enough oil to reach the pinion, your likely OK.
How are the carrier ends set up to allow the oil in and out of the axle tubes? On many you have to notch or drill the shims or the oil can migrate into the axle tubes and not drain back like it should.
Click to expand...

Knowing where the fill plug on the 8.8 is, it does look a little low but like 8Mud said, you're probably ok. The differentials not going to seize up or anything from being a hair low on fluid. Now, does it affect your LSD??? I'm not sure...but that is what I'd be concerned about. Not sure how water and low fluid affects LSDs.
 
I'm guessing it's still frothy because you only let it sit for 20 min. before opening it up. That oil is getting mixed with air all whole time you're driving, so it makes sense that it would have some air bubbles in it shortly after being driven. Just a thought.
 
did you put the ford friction modifier for the lsd in?
 
alex22 said:
s.
The axle: 8.8 with reused stock 3.73 gears, all new bearings, super88, and a limited slip. I had 3 quarts of Valvoline 85w140 with some limited slip additive. The XJ has 4.5 inches of lift and 31 inch tires.

My question, first of all, is that froth bad, if so would you say its caused by too much oil or not enough oil?

~Alex
Click to expand...

Ok for starters.. too little oil will cause that condition, as well as too much oil. So it goes both ways.. Second just use 75~90wt oil in your diff, you don't need the 140wt if your not towing anything heavy.. Run the Redline at the proper level and be done with it.. just fyi here...
 
I drained both my D30 and 8.25 a few weeks ago. Both had the oil changed this past May, so both differentials had the oil in them for about 6 months.

This past September we had significant flooding around in the area and I had made multiple watercrossings with water above the axles.

The D30's oil looked perfect. The 8.25's looked fine too except I had some bubbling like you did. I was told it was a bit of water. And since the pinion and tube seals in the 8.25 are not new (the D30's seals are all new when I replaced the pinion and carrier seals in May, and also added some Alloy tube seals) my guess is that the rear axle isn't completely water tight unlike the front.

So it could be a small amount of water I suppose.
 
You must log in or register to reply here.

Similar threads

R
Low Oil Pressure, Bearings, etc... some questions
Replies
8
Views
627
SpringDog
S
X
XR3Z's vs 19 XF2E's (2001 XJ) and so much more
Replies
5
Views
2K
xcm
xcm
R
Detroit Trutrac 913A589 3.73 and down $225 OBO.
Replies
0
Views
253
rmoorex
R
H
Low oil pressure led to a full year down
Replies
1
Views
877
tjmotter
tjmotter
C
4.0 Loosing power, dying
2
Replies
20
Views
2K
coxj99
C
Back
Top