I'm losing gear oil from my rear differential. Pinion doesn't seem to be slinging fluid. No leak at the axle seals. Pumpkin is not wet and there is no fluid on the ground. Diff fluid is caked on the underside of the bed and back of fuel tank.
Leak may be somewhere on top of the diff. Maybe the ABS sensor or breather tube, I can't tell.
I discovered there was a leak when I started to hear grinding noise from rear wheel bearings. Checked diff fluid and it was more than an inch below the fill hole. I've re-filled to proper level but still get grinding so my bearings are shot. I want to drive the truck a while then look for wet spots, but I don't want to get bearing grit in my diff fluid.
2008 Hemi Crew cab with 3.92 and anti-spin rear. Diff is locking up just fine.
I'll order new bearings and seals today.
Any suggestions would be most appreciated.

 

If it's slinging it around, that's the pinion seal. There is no pressure in there to get it to travel any further.

 

1/2 ton rear with LSD is a timebomb, the ears of the lsd rest on steel bushings that eventually split and grind the housing. Makes a mess, ruins the bearings, and weakens the bearing cap and where they land in the housing. Pull the cover and inspect it. I'd bet you're looking for a used good housing to build in the end. Pessimistic, maybe... hope I'm not correct.

 

Thanks for the reality check heyyou, leak has to be pinion seal. It fooled me because the area around the pinion and yoke are dry, and no drips on the ground. The biggest section of the oil was on the driver's side, but I guess that is how the oil is slung by the drive shaft. I"ll add a pinion seal to my cart.
Fj5, I heard that the LSD/anti spin rears were improved in 2007. Mine has been great so far and I have 180k miles. I'll open the diff this week and let you know what's on the magnet.

 

I dunno, wasn't there some kind of pinion nut failure that was on recall in later years?

 

Early 3rd gens, at least through 2005. There was a later one for the early to mid 4th gens and Durangos.

 

I opened the diff and fluid was clean. I'm relieved and will order wheel bearings and new pinion seal.
Seems odd that wheel bearings on both sides start making noise at same time.
I really should have noticed the gear oil on the underside of the bed.
If bearings are really bad I'll post pics.

 

Both bearings live in the same environment.... and if the diff was low on fluid, the axle bearings are the first things to go.

 

Part one of project complete, installed rear wheel bearings and seals. The bearings were intact and looked good, but I did notice some grit on the driver's side axle shaft. The driver's side was the noisiest. Used Timken bearings and seals. Seemed like quality parts, but not made in USA.
I used a bearing puller and slide hammer loaner from the parts store. Pulled the bearing and seal out together.
Used the 90 minute gasket RTV to seal up the rear. Got more work to do before driving the truck, so there is time for the RTV to set up, even in the cold.
Next is pinion seal. Just got the 32mm socket from harbor freight.

 

New seals and bearings installed. I still have the grinding/scraping noise. It's not a whirring, whining, or mechanical sound at all.
Anyone ever heard of this before?
I'm thinking it's probably internal to diff, some combination of pinion bearings, carrier (side) bearings, or ring/pinion gears. I think you were right fj5!
Decision to make is; do I do a diff rebuild (bearings and crush washer) or do rebuild with new ring/pinion/LSD? If new ring/pinion, then what brand? Yukon is same price as Mopar.
Your recommendations and experience would be much appreciated.