ok My 99 makes this noise when the 4wd kicks in, its a whurring noise from the front left axle area, I took it to ford and they said my transfer case was acting up. Ok go to my local mechanic and he replaces it with 9k mile case. Cool issue solved or so I thought. Icey times in VA require 4wd as of late and what happens. The noise is back, wtf?!?!?!?

The sound happens at low speeds and goes away at higher speeds, again its a whurring noise, low pitched. The truck drives fine and pulls good in 4WD. Anyone have any advice for me. I searched and couldn't find anyone with the same issues. Please help!!!

Thanks,
Jason

Bump, someone has to have heard of this. My other buddy who has a 99 has had the same issues. Could it be something that needs greasing?

I assume the boots are still good? what about the fluid levels in the front diff.? Did you ever have this noise before?

Well It only happens when 4wd kicks in and my mechanic topped all the fluids off when he replaced the transfer case last month. That being said the boots are also in tact as well. :(