front diff oil is black

[centraloregoncruiser]

So I bought 92 cruiser from guy who had the front diff. Rebuilt from a dealer for 1100$ now 1 1/2 years and 12000 miles later I went to change diff fluid and the stuff is black. Looks like grease is in it. The breather valve seemed to work. Doesn't click or anything. Do u guys think it is OK to keep running that way if I change fluid often. Or do I need to get seals redone. I need to replace front brakes soon would that be a good time to do it. I'm decent on engine but this kind of stuff is out of my element. Any info would be helpful. I use this as adventure car.skiing rafting dirt roads to backpacking. No major off reading. Thanks

 

[SUMMIT CRUISERS]

Your inner axle seals are not sealing allowing moly (black) grease from the birfields to mix with the diff. oil. "Is it OK to keep running it that way?" Not a problem. I'm certain most of the 80's out there are in the same situation or have been before. I would read up on how to change the seals and do so at your convenience. You might also look into relocating your differential breather and remove the check valve in it when you do so. The "Search" function and FAQ are great place to start.

BTW, Welcome to Mud and congrats on your purchase!

 

[Duiser Offroad]

Changing the rotors is a great time to address it. Its a pretty straightforward job, just time consuming. We have a youtube video you can watch for help.

So I bought 92 cruiser from guy who had the front diff. Rebuilt from a dealer for 1100$ now 1 1/2 years and 12000 miles later I went to change diff fluid and the stuff is black. Looks like grease is in it. The breather valve seemed to work. Doesn't click or anything. Do u guys think it is OK to keep running that way if I change fluid often. Or do I need to get seals redone. I need to replace front brakes soon would that be a good time to do it. I'm decent on engine but this kind of stuff is out of my element. Any info would be helpful. I use this as adventure car.skiing rafting dirt roads to backpacking. No major off reading. Thanks

 

[inkpot]

Your inner axle seals are not sealing allowing moly (black) grease from the birfields to mix with the diff. oil. "Is it OK to keep running it that way?" Not a problem. I'm certain most of the 80's out there are in the same situation or have been before. I would read up on how to change the seals and do so at your convenience. You might also look into relocating your differential breather and remove the check valve in it when you do so. The "Search" function and FAQ are great place to start.

BTW, Welcome to Mud and congrats on your purchase!

I have changed a lot of diff oil on 80s over the last 2 years. It is pretty common to have some contamination from the Moly in the knuckles. It is MUCH better to have a little Moly leak into the axle housing that it is to have gear oil leak out into the knuckle and wash out the Moly. I would refilll the diff and check/refill the knuckle with Moly to make sure it is 3/4 - 2/3 full. Some color contamination is not a problem, but if it gets bad enough that the diff oil looks like black pancake batter coming out, then it is time to get the axles seals replaced. John

 

[NLXTACY]

^ just went thru this. My inner axle seal on one side failed in under 3 years.

 

[centraloregoncruiser]

^ just went thru this. My inner axle seal on one side failed in under 3 years.

Is it possible to tell what side goes

 

[centraloregoncruiser]

Replaced oil and I guess monitor until winter when I do brakes

 

[NLXTACY]

Is it possible to tell what side goes

Only if the gear oil gets into the knuckle. You can look into the knuckle's square plug and see which is contaminated.

 

[atomicshawn]

I had similar issues. My saga: https://forum.ih8mud.com/threads/moly-or-metal.475563/
I went to the trouble of replacing the inner seals... again. It changed nothing
I'd just make sure your birfs dont go dry

 

[NLXTACY]

I have a brand new OEM birf and Inner axle so no previous oil seal grooves even though mine were barely noticeable. Either way, I don't see an inner axle leak on that side for a very very long time.