Strange oily GOOO. (1 Viewer)

[Silicon 70]

I was changing my rig's front diff oil today and when I unscrewed the drain plug, alot of really REALLY black diff oil came out of it. I mean almost like molasses type stuff and it had a shade of green in it, which is kind of puzzling because when I changed the rear diff it was just a see through brown type of color (KEY WORDS ARE SEE & THROUGH).

Now I don't know the last time it was serviced because I just acquired this rig, but the front diff was a little hard to loosen. Had to buy a 6 point socket and B'Laster to take the darn thing off.

I hope nothing is wrong, but my mind keeps telling me it might be an oil seal that ruptured and is letting in bearing grease.

Someone please prove me wrong.

 

[RavenTai]

my mind keeps telling me it might be an oil seal that ruptured and is letting in bearing grease.

Someone please prove me wrong.

well close it is most likely birf grease and if so you need a birf repack to replace the seal between the knuckle and diff, pull the fill plug on the knuckle and check for gear oil contamination in the knuckle.

also relocate your diff breather or at least delete the evil flapper on the stock breather

search for details.

 

[firetruck41]

I second the axle seal letting in birf grease, time for a birf repack! Plenty of info if you do a search, also check the Technical Links page from the Ih8mud home page.

 

[Silicon 70]

"also relocate your diff breather or at least delete the evil flapper on the stock breather"

Uhh what does that mean and where can I find it.

Is a birf repack easy? I usually work on cars not SUVs.

 

[alaskacruiser]

I asked the mods to include this and other links in the FAQ a while back but still don't see them. Here it is:

http://www.safari4x4.com.au/80scool/tech/breather/Breather.htm

 

[tarbe]

The main reason it has been suggested that you mod you breather is that the stock breather easily fails closed, forcing the "breathing" to occur through your axle seal. This effectively can suck grease into your axle housing from the knuckle when your hot housing cools (especially rapidly like when you hit cold water).

The front breather originates on top of the tube just on the driver's side on my FZJ80...been too long since I had an FJ80 to remember if it is the same spot...just look, you'll find it. Do a search on diff breathers to find pics, etc. I extended both of my breathers into the engine compartment and terminated in a fuel filter (they are Y'd together above the front axle).

 

[Kalawang]

The main reason it has been suggested that you mod you breather is that the stock breather easily fails closed, forcing the "breathing" to occur through your axle seal. This effectively can suck grease into your axle housing from the knuckle when your hot housing cools (especially rapidly like when you hit cold water).

The front breather originates on top of the tube just on the driver's side on my FZJ80...been too long since I had an FJ80 to remember if it is the same spot...just look, you'll find it. Do a search on diff breathers to find pics, etc. I extended both of my breathers into the engine compartment and terminated in a fuel filter (they are Y'd together above the front axle).

Tarbe,


Thank you for the details. I've been wanting to do something similar but lacked sufficient info. I think I can now proceed to extend my breathers.


Kalawang

 

[firetruck41]

"also relocate your diff breather or at least delete the evil flapper on the stock breather"

Uhh what does that mean and where can I find it.

Is a birf repack easy? I usually work on cars not SUVs.

Birf repack is a messy, time consuming job, but not very hard, with a service manual and the tech link, you will have all the info you need, other than that you need a few special tools, like a fish scale, brass drifts, seal puller and driver, torque wrench and the normal assemblage of sockets, etc. You will also need the PROPER greases, make sure you follow the recommendations.

 

[Rookie2]

What does the outside of your knuckles, and the grease inside the knuckle cavities look like?

 

[Darwood]

My front diff oil looked the same last weekend. So I drained and filled it. Then this weekend I drained and filled again. The fluid was darker then when it went in, but I was able to see through it this time. I'll probably drain and fill in a couple weeks to see how things are going in there.

I replaced my axle seal about 10k miles ago. When I checked my birfields through the square plug, the grease looked fine. Also the outside of my knuckles have a damp area on them noticeable by a darker color.

I'm gonna take the advice CDans gave me and if the next couple drain and refills don't look to bad, not do anything until I eventually regear.

Pretty much I think the key is what does the grease in the birfield look like?

 

[concretejungle]

Digital, just looking at the pic in your avatar, did you buy ben's old rig? I imagine if so the diff breathers are probably allready extended. Did you buy that rig that bradass was selling?

 

[Silicon 70]

I'll check the grease tomorrow and report back to this thread.

 

[tarbe]

Just remember that when you look through that plug (or the hole for the ABS sensor for that matter) you are only looking at the grease in the outer cavity of the knuckle. You are not looking at the grease (quantity or condition) in the birfield joint itself. There are pics on here that show this clearly if you search for them. If I were an artist, I'd draw a picture! But alas, I can barely spell artist...

 

[Beowulf]

Kalawang,

This thread has everything you will need to know about extending your diff breathers.

-B-