Nasty "oil" in front diff - How bad is bad?

[ashooter]

I drained/filled my front & rear diffs and t-case with M1 75w-90 yesterday. Oil that came out of the rear diff looked like it was fresh out of the bottle, t-case looked about like used motor oil... But the stuff in the front diff was nasty looking! Looked about like Hershy's chocolate syrup. Maybe a little bit lighter consistency and a very black color = moly color. There was also about 1/2 CC or so of what looked like black clay residue stuck to the magnetic plug - about 3 or 4 times as much as was on the other two plugs.

I assume this means at least one grease seal is no good, so the question is: Should I STOP driving the truck and order all the stuff to repack the birfs as soon as I can get hold of C-Dan? There are no clicks or other noises that would otherwise make me worry, just nasty looking "oil" that came out of that front diff.

I plan to do a birf repack ASAP, but would it be foolhardy to drive the truck around town for a couple of weeks before I get around to it?

 

[OGBeno]

I drained/filled my front & rear diffs and t-case with M1 75w-90 yesterday. Oil that came out of the rear diff looked like it was fresh out of the bottle, t-case looked about like used motor oil... But the stuff in the front diff was nasty looking! Looked about like Hershy's chocolate syrup. Maybe a little bit lighter consistency and a very black color = moly color. There was also about 1/2 CC or so of what looked like black clay residue stuck to the magnetic plug - about 3 or 4 times as much as was on the other two plugs.

I assume this means at least one grease seal is no good, so the question is: Should I STOP driving the truck and order all the stuff to repack the birfs as soon as I can get hold of C-Dan? There are no clicks or other noises that would otherwise make me worry, just nasty looking "oil" that came out of that front diff.

I plan to do a birf repack ASAP, but would it be foolhardy to drive the truck around town for a couple of weeks before I get around to it?

You're fine driving it...just put some new fluid in there (get cheap stuff--i.e., Coastal 80w90) and do your birfs sometime in the near future.

If it's any consolation, I've seen sludge/pudding come out of front diffs, and the truck was driving fine prior....

 

[TX_TLC]

Refill the diff and make sure you have grease in the knuckles. But plan on doing the rebuild asap.

 

[RCFloyd]

I found this to be true in mine as well, and the Birf's were done recently. What I found was NOT done however, was that the Front Differential Breather was totally clogged, and when I removed it there was a big whoosh of air rushing in. That alone creates a vacuum that pulls in the grease, so make sure that is clean & functioning. The Breather Relocation is also a great idea...

Robert

 

[RavenTai]

That is actually by design not necessarily plugged, there is a one way flapper valve at the top of the breather, it is recommended to remove this valve and extend the breather to a drier location. This lets the seals work better, I tied both diffs transfer and transmission together and routed them to a filter near the master cylinder

 

[e9999]

soupy oil is common instance with the 80s from what I read here and observed.

No biggie. Make sure there is plenty of grease in the Birfs and it's likely fine to drive for a while.

 

[ashooter]

Thanks guys. Like I said, there's no other symptoms that would make me worry. I will definitely bump the birf repack up to the front of the "to-do" list, though.

 

[peepers]

That is actually by design not necessarily plugged, there is a one way flapper valve at the top of the breather, it is recommended to remove this valve and extend the breather to a drier location. This lets the seals work better, I tied both diffs transfer and transmission together and routed them to a filter near the master cylinder

did you write it up? parts list?

 

[ashooter]

One other question:

When you remove the "pipe plug" from the top of the steering knuckles and pump grease in there, how much grease do you pump??? Enough to where it starts to come back out the hole around the grease-gun nozzle?

 

[fzj80kidpen]

ashooter,
Not that much. A couple squirts is enough. No big deal in your case as the seals are already blown. Also when you do the repack be very carefull with all you torque ft/lbs. Get a good click wrench and make sure you only repack to 3/4 full inside the knuckle. Many people fill it 100% then when it get hot that will also blow the seals. Its a fun messy project but well worth your time to do.

 

[dfmorse]

Peepers;

See the tech section link below for George's write up on breathers and stuff.


http://www.george4wd.taskled.com/breather.html

...

 

[e9999]

One other question:

When you remove the "pipe plug" from the top of the steering knuckles and pump grease in there, how much grease do you pump??? Enough to where it starts to come back out the hole around the grease-gun nozzle?

I had been going on for a while with the "a few squirts" recommendation and noticed that there was grease showing only on the bottom part of the knuckle sphere. Debated a bit the "can it be too full?" issue in its various forms. And finally concluded that I should fill it completely (until it comes out). Which I did. Now, at least there is grease over most of the outside of the knuckle. Much better I think.

 

[ashooter]

I had been going on for a while with the "a few squirts" recommendation and noticed that there was grease showing only on the bottom part of the knuckle sphere. Debated a bit the "can it be too full?" issue in its various forms. And finally concluded that I should fill it completely (until it comes out). Which I did. Now, at least there is grease over most of the outside of the knuckle. Much better I think.

Actually, I'd already gone way past the "few squirts" level. Put about a 1/2 a tube of grease in each one before I ran the grease gun dry.

I figure that MUST be a helluva lot better than it was before, but I would also assume that means that the vast majority of the grease that was in there to start with ran out into the drain pan when I changed the front diff oil Friday night.

Needless to say, the birf repack job that I have been dreading (putting off) has been firmly bumped to the top of the to-do list.