When my truck sits all day and its cold out, my truck in 2WD will make a whining sound going down the road, sometimes its a grinding sound almost. Appears to be coming from the passenger side of the truck towards the front. Engaging 4x4 gets rid of the noise, and the noise will usually disappear after the truck has been running and warmed up. I've changed my ball joints recently and everything looked good and yes it had done it a time or two before hand. What causes this, and how do I fix it?

 

Vacuum problem.
your answer is here:
https://www.ford-trucks.com/forums/8...then-some.html

 

Actually I am beginning to wonder if it is. I had my vacuum lines off when I did both bolt joints hoses looked to be in great shape. My truck doesn't run rough, idle rough or none of the that. Is there anything else a motor or something it could be? I guess when it warms I'll start tracing vacuum hoses.

Ah it might be the seal on the actuator.

 

See bold and italized

If engaging 4wd makes the sound go away, then you likely have vacuum leak causing the IWE's to partially engage, or attempt to partially engage. Could be a bad solenoid (on the firewall, passenger side). Could be a bad IWE. Could be a cracked vacuum line. Could be that you didn't fully seat a line when you reconnected. Hard to diagnose from the keyboard. But those are all likely scenarios if engaging the 4wd makes the noise stop.

 

Its just one side that makes the noise. So its likely related to that side, and not the solenoid. If I am moving down the road however and engage my 4x4 which I think is related to the fact my ABS light is on, the other side will make a terrible grinding sound as well. I have to not be moving at all to get it to engage correctly. When my ABS worked this didn't happen. Either way as soon as this crappy weather goes away I'll be outside looking into this. Right now its 10 degrees.

 

How is the ABS light (likely related to the sensor on the wheel) related to the 4wd system?

 

Wondered the same thing Chandler. I had very similar noise and it was the solenoid (~$30-40?). But I do not recall it being side specific, just an awful noise from underneath.