Vibrating/ humming coming from drivetrain?
So last winter I was driving on the highway and all of the sudden lost 4th gear. I took the car to the shop and on the way got it back. It was still a little funny feeling but my mechanic went in and said all he saw is that it was a little low on fluid. Now, there is a humming that sounds like it is coming from the transfer case, axle, or transmission. The sound gets louder the faster I go and is not based on RPM's. It also gets louder when I hit a bump but quieter the higher the suspension travels, then settles in the middle again at a medium noise level. I havent noticed a difference in how it is running and still has all its power, 4wd, and all functionality. It's gone this long with the noise and over 10k miles, but Im still curious if this could be something serious.