I have an 08 4.0 sohc with 46k miles, and Ive had this noise as long as I can remember and it may be totally normal, it seems to be a very slight rattle coming from the driver side in the wheel well area when it is idling, when you increase rpms the noise seems to fade. Its not loud and the engine seems to sound/run smooth. I usually only really notice it when im in a drive thru next to a wall, or if I stick my head down by the drivers side wheel well. I used to own a 2004 ranger with the 3.0 and it made the same type of noise as well, and noticed it in drive thrus also. The truck has motorcraft 5w30 synthetic blend oil and has been changed every 3k. If anyone has any thoughts please share.

Thanks

 

My 07 does the same. SOMETIMES. lol drives me crazy, but when I pop the hood and actually look for it, it never seems to want to do it. I have noticed it seems to do it when I have the AC on though.. IDK.

 

Check inside the harmonic dampener the weight can become lose and rattle around at low engine speeds. Happend to me it sounded like a rock being shaken in a metal bowl.

 

I've got an 08, 4.0 sohc and can't say I've ever noticed any sounds like that.

 

mine makes a sound but only when the ac compressor runs

 

Timing chain, maybe? It's problematic on the 4.0.