Was running to walmart real fast today and on my way back out of no where my car starts making a really loud humming noise. It happened several times at the route back I was doing speeds between 25-40mph. It seemed to fall off when I backed off on the throttle but hard to say for certain because it only was making the noise for short periods. The noise seemed to be coming from the front/front right of the car.

I took the car out a second time and was going to slide it into neutral when the car started making the noise, again I did speeds between 25-40mph. This time the car only seemed to do it as I was completely off the throttle letting the car coast to a stop. Only the one time it did it while normal driving, putting it into neutral made it quiet down fast but then came back shortly after while still in neutral. The noise however was not as loud.

It's important to note the car has been making a humming sounds around 25-40mph but today it was a lot louder. Previously it was really faint and not this frequent. The weather today was also pretty cold for our area, around 25-30 Fahrenheit. My main 2 guesses would be wheel bearing or transfercase. I have been trying to get my transfercase fluid done but shops want upwards of 500$ for the job. I'm calling a guy during the week that's 40minutes away, he only does jaguars so I should be in good hands there.

 

Carrier bearing is known to be louder when drying out at colder temps. Do a search here on how to needle grease it (w/pics). Pretty good results on most, not so much on others.

Also search for transfer case fluid change on here. There are a bunch including one (w/pics) by me with method, tools, etc. Not hard, just requires some patience. Mine uses tools instead of the alternate tipping the car from side to side method.