A number of years ago I purchased a 2000 f-350, 4x4, 7.3 turbo disel, crew cab, long bed. it’s been a great truck, many long vacations and work trips pulling a heavy trailer have gone off with out a hitch. ( trailer jokes… Ha!). A few weeks ago I noticed that the rear differential was looking a little wet with oil so I cleaned it all up to attempt to locate where the leak was coming from ( it was the cover) but durring this process I figurd I would check the fluid level just to make sure it wasn’t too low from the leak…so after removing the plug and sticking my finger in it came out coated in what I could only describe as some combination of axle grease and oil. It smelled terrible but I think that the gear oil that is supposed to be in there could be the cause of that but it was a lumpy consistency, almost like a curdled milk. A friend of mine swears that it’s axle grease in with the gear oil but after looking through the manual I done think there should be any because it has a full floating rear axle. A Dana 10.5" to be more specific… Not sure that it matters. The only thing I can i figure is that someone packed the bearings with grease not realizing that they were supposed to be lubricated by the differential fluid. Assuming my hypothesis is correct, Is this something I should be concerned about? The differential seems to be working fine, and by that I mean that it hasn’t broken yet. Should I change the differential fluid? Do I need to pull my hubs apart and clean them out. Do I need to be trying to flush the lumpy ness out of the differential and axle housing, and if so how would I go about that. Or am I way over thinking it. Is it just better lubricator with axle grease in there or could it be something else all together? Some other contaminant coagulating the gear oil? Any advice would be appreciated. I’d take it to a shop but it seams that any time I take my truck in it costs a small fortune.
I’ve seen this before and I think you should just leave it alone. If it’s not making noise…leave it be.
Since you’re planning to pull the cover to fix the leak anyway, I’d first find out exactly what lube is specified (does it have limited slip?), clean out what I could get to (without using solvents), put on the new gasket, fill as needed, and go. Wonder if prior owner was wanting to quiet down a whine?
I’d get the axle code off the door jamb and go straight to the dealer and buy whatever lube they suggested. Ford can be very specific about the gear oil they require, and I’ve seen the consequences of just using what grandpa uses in the 78 dodge he drives…
I doubt someone packed those bearings with grease, but you never know. I’d just drop the cover and clean it up real good, slap it back together with some new RTV and lube ith up with the Motorcraft juice provided and call it a day.