Hello, I have a 2001 F150 4x4 5.4l with 105k miles. I started it up today to go to lunch and it made a knocking sound on start up that lasted maybe 20 seconds. So i shut it off and checked oil. All ok. Started it up agian and it knocked but not as long as it did previously. I started to drive and higher in the rpm range before the trans shifts it makes the same knocking sound. Left off the pedal it goes away then rev it again it doesnt make the knock till around 2000rpm mark it I remember correctly. It makes the noise in all gears, parked or driving. It runs great, no power loss or mis-fire. Could it be a spark plug on the verge of blowing out or is it time for a new motor? Im going to look at it more tonight when I get off work. Any help would be great. Thanks.

 

I can't get a good feel for your discription of the noise.
If the motor runs smooth and you still hear the noise, it seems it would be something like the cam chain tensioners up front.
Try to see where the noise is coming from for a start.
Good luck..

 

My truck made a similar noise to what ur talking about timing tensioners and guides were wore I guess u could say and left slack in the chains and spun 3 rod bearings! I drove it till it blew and bought another motor