Flushing a rear diff.

[06MountaineerPA]

Hey fellas,

My mom just picked up a 07 Mounty. It needs some work. Mainly both rear axle seals are leaking. The previous owner said he didnt have time to replace them and he just used whatever fluid he had to top it off. Hydraulic fluid or used oil just to keep it lubed was what he said.

So I want to flush out the diff when i install the new seals and add new fluid. So what can I use to clean the diff. Do I add something and drain or take the cover off and wipe it down.

 

[massacre]

You’ll have to remove the cover and drain the fluid to replace the axle seals anyways.
So I would get the cover off and the axles out, and then wipe it down, maybe a little brake clean to get most of it off.

 

[michael loibl]

Agreed, if the cover has to come off to do the actual steals anyway, might as well let it drain thoroughly, spray it down quick, and get it all out
I kind of impressed that the seller actually informed you that he filled it with the wrong fluids, most guys wouldn’t have admitted that

 

[06MountaineerPA]

Maybe I explained it wrong, from the video I watched, I just have to pop the axle shafts out, pry out the seals, seat the new ones and re-install axle shaft and replace fluid. It didn't say anything about removing the cover. I want to flush out any of that mixed fluids the guy previously used.

 

[boominXplorer]

The only way to remove the cover is by pulling the diff. I'd be afraid of the condition of the rear bearings and wouldn't pull the rear cover unless its leaking or has bearing noise. I'd just drain it and leave the plug out overnight and refill with 75-140.

 

[06MountaineerPA]

Thanks for the quick replys and help offered. I'll just let it drain over night then.

Any tips for doing the seals? It didn't look hard from the YouTube vids I seen.

 

[Mbrooks420]

I’d be concerned about the gears. Most hydraulic oils, and especially used oil doesn’t have near the “cushion” of the thicker gear oil.

 

[massacre]

Have to remove cover to get c clips out, right?

 

[donalds]

I'd drain and fill two times just for piece of mind