getting a burning rubber smell when 4WD is engaged

The past two days i've noticed a burning rubber smell when my 4wd (4hi) is engaged. Truck does not need to move for me to get the smell. last night I put the truck in 4wd to turn around in my driveway and left if 4wd so I could get out this morning. When I started the truck to allow it to warm up (10 min or so) when I got to the truck I had the smell. This only occurs when it is in 4wd. as soon as I get out of my driveway I switch to 2wd and have no issues or smells. I do not feel anything slipping when it is in 4wd either. front differential fluid and transfer case fluid was changed this past summer. I have also used the 4wd a handfull of times prior to this since the oil change with no issues.
2009 6cyl w/181,000 miles

 

id be checking the serpentine belt and pulleys. in or out of 4wd has nothing to do with this issue if its just running static

 

checked the serpentine (also replaced over the summer) no signs of excess wear, no squeeling. I cant explain it but if i start the struck in 2wd I get no smell, I stat it in 4wd or run it in 4wd, I get a smell.

 

Can you sniff out the general area where the smell is strongest? In the cab, (near switch or behind the glovebox would be good areas), under the hood..., around the transfer case...? I'm having a hard time believing that the smell is related to 4wd if its working.

Another thought - have the roads in your area been de-iced with liquid mag chloride brine? That crap stinks a lot like burning rubber when it gets on hot exhaust.

 

Could also be a fluid leak flinging on hot exhaust

 

I had this happen , ended up being excess grease from the U joints grease nipples on the front 4x4 driveshaft getting flung onto the exhaust , that may not be the case for you though OP

 

I will check the grease, I spun the wheels 2days ago trying to get out after the recent storm. I smell it most coming near the driver side wheel well.

 

Happens on mine too.

 

E-brake on?