k6monster

I just ran out of warranty on the 6th and now I noticed that there is a loud "buzzing" noise coming from my front drivers side. I really notice it when I slow down. If I put it in 4x4, the noise goes away. I didn't start noticing it until I used 4x4 for the first time this winter. The truck is a 04 fx4.

kifels

check your wheel bearings. I had the same thing happen a while back.

06fordf150

hey it could be that the vacuum solenoid for the four wheel drive has gone and is a pretty comon problem in theese trucks water and crud gets in there and it will make the truck try to engage 4wheel drive and it will make a noise something like you said a buzzing or like mine sounded like i was dragging a stick down the rode i think the part costed me like ten bucks and my brother changed it out and fixed the problem in about 15 minutes or less!!

Smokin Lariat

There's another thread right here now reporting a ratcheting noise - which could also be your IWEs or that solenoid. Is the sound like ice being crushed in a blender? If so, that's it. Here's that thread:

ratcheting noise while engaging 4wd, 2007

I also just posted there, here's another thread that just appeared of a guy that has the solenoid for sale.

the old part allows moisture into the vacuum system, the new one, identical but with a small plastic top cover does not. Here's the thread where the guy has it for sale:

New 4wd switching soliniod # 6L3Z-9H465-B

I had that problem and the IWEs were replaced under extended warranty, the solenoid is a simple bolt off and on change easy to make.

k6monster

I replaced the selenoid last night after work and it was fine on the way home. Then on the way to work it started doing it again. I have to find time to go see if a hose came off before I give in and take it somewhere.