Rear differential leaking tons of fluid

Hit 500 miles of my breakin period for my new 5.29 gears and did the differential oil change on my own. followed the instructions to the letter. took it on the highway for the first time to and from work today and saw a few oil spots under the car after i brought it home. was horrified to find oil sprayed all over the underside of the truck from the differential rearward. Anyone have any idea whats going on? the fill and drain seals do not have any oil around them.

 

Could be a few things, namely poor pinion bearing preload allowing the pinion to move and kill the seal, or possibly a bad seal itself or a bad seal install. I’d take it back to the shop.

If they change the seal, I’d tell them to use an OEM one.

 

From the looks of it, the pinion seal let go.

 

So, the only thing that I personally did to the truck was drain the dif oil, and refill it. torq'd the fill and drain plug appropriately etc. Is there any way that I caused this by just replacing the dif oil?

 

It wasn’t leaking at all before you changed the oil?

 

That is a really odd coincidence, but I can’t think of how anything you would have done would have caused the problem.

What fluid was it originally filled with and what did you use?

 

that pinion seal is leaking

 

So I got the gears from Nitro and I also got the differential oil they recommend (their brand). So I gave it all over to the shop and assume they used that oil because they gave me back less than I gave them. When I did the dif oil replacement I used that same oil. (https://nitro-gear.com/para-synthetic-plus-gear-oil.html)

 

Pinion seal, as stated previously

 

I don't see how I wouldn't have noticed it when I got under there and changed out the dif oil yesterday. At the same time it makes sense that it was something I did because it wasn't leaking until I changed out the fluid, but then again all I did was drain fluid and fill fluid so that doesn't make sense to me either.

 

Sounds like you overfilled it.

How many quarts did you put back in?

 

The entire underside of the rear of the vehicle is covered in oil; like an oil filled balloon burst above the differential. The seal isn't leaking now, as in there are no oil spots on the garage floor, and I don't see any oil around the area of the pinion. Would the pinion seal leaking be able to cause that much oil in such little time?

 

Surely you’ve got to be able to find some wetness on the axle somewhere which is how it would have sprayed the underside. Where is the rear axle wet?

 

So I put in 4 quarts and then a little extra until it started to slightly drip out of the fill hole.

 

thats on the higher side. Some take 3, perhaps a tad more. I’ll wait for others to chime in here

 

all over the front of it, both left and right until you hit the leaf springs. There is enough oil above the differential hanging from the bottom of the truck to drip, and a large amount on the fuel tank cover near the pinion.

 

Maybe you have a transfer case leak or a front diff leak that is spraying backwards? Can you find anywhere the wetness would have actually come from? Like one of the locker connectors? One of the diff bolt holes or the diff gasket, etc?

Take off the 2 bolt locker connector shield and see if any wetness is in there. It’s gotta be a bad leak to be getting all over everything like that…should be obvious to find. If not anywhere on the rear axle, then I think you should look closer to the front.

Still doesn’t make any sense just from you simply draining and filling.

 

Was the truck level when you refilled the fluid?
About how much fluid did add?

If the truck wasn’t level left/right, you can over fill the diff.
As the fluid will run down the axle tube to one side.

I always park the truck on level ground Front/Back - Side/Side.
Fill it up until it runs out the fill plug.

An over filled diff will build more pressure. Technically it shouldn’t of the breather is working, but don’t think for a minute that the diff breather always works. Take it from us guys that have blown axle seals from a failed breather.

 

what would overfilling it cause to happen?

 

My 2021 OR MT takes 4.5 liters. Seems like a hell of a lot but it is a 3rd member and the tubes are huge and full of oil so it makes sense. His numbers sound right to me.