So got to a job this afternoon and smelled a grease smell by the rear of the truck. Got under it and saw some black liquid accumulated on the rear passenger side backing plate behind the rotor. But it didn't really have a smell, certainly didn't smell like gear oil.. But it doesn't appear to be brake fluid either.. I blew in the diff breather hose and it's not clogged (5k miles on truck, shouldn't be clogged yet).

When I got home, I didn't smell it anymore and it didn't appear to be anymore accumulation than before. I'm gonna keep an eye on it for the next few days.

Any ideas? Seems like it has to be gear oil from a leaking hub seal, but just thought it was odd that it didn't smell like gear oil.

 

Could be that a seal was damage or put in improperly during assembly, so you could be leaking from the differential and it is weeping out that way.

I had a seal blow in my truck and I didnt find any oil in a puddle but notices it on the rim of the rear tire, when I took the tire off I could see that the brake was contaminated with oil and it was not brake fluid. I then knew a seal went and started the job of repairing it.

I would keep an eye on it liked you planned, lord knows you wouldnt want to lose fluid out of the rear end

 

Unless there is a new type of 80-90W there should be no mistaking the smell....sorry to hear of a problem with your new truck. I would pull the plug and check the level.

 

Well, hasn't smelled or leaked at all today.. So not sure what happened, but hopefully it was just a fluke and will act right from now on. Who knows.

 

I agree here, you or the dealer should have a look and see how much fluid is present in the diff. Last thing you want to do is find out you dont have enough fluid and the rear goes, that's no cheap fix.

I would gather you are under warranty, so I would take it to the dealer and let them know what you found and ask them to check the diff, they should do it at no charge I would think, better to be safe then sorry

 

Finally took it in to the dealer. Needed a new axle seal. All is good now.

 

Great it was as simple as a seal. Other than the inconvenience of having to taking it back and waiting for it, nice having a warranty.