2005 F150 5.4L
Out of no where today while I was driving a loud tapping/knocking noise started midway through my drive, then it went away after 30 seconds, then it came back. After doing some quick research I noticed some said a loose spark plug can cause that and i had recently changed my plugs about a month ago. Pulled all the plugs and 1 was loose so I was sure that was the issue. Re-torqued all the plugs, put everything back together and started it back up and noise was still there. If I let it idle, sometimes the noise will go away for 30 seconds or so but it comes back eventually.

Here is a clip of the noise - https://imgur.com/a/j0aeHLE

As you can hear from the video, it is most loud on the passenger side near the wheel or under the truck it is loud as well. No CEL's.... for the short time i drove it home, didnt feel any loss of power or anything out of the ordinary other than the noise itself.
Any suggestions as to what it could be? The sound does increase with the rpm's if you rev the engine or whilst driving.

 

phaser or perhaps cam follower problem.
is it always there or only after warmed up?
Does it go away above 900 rpm?

If it's always there I would stop driving it and remove the valve cover and check out the cam followers before it wipes out the camshaft

 

Temp of engine doesn't seem to affect it at all neither does rpm.
The weird part is like i said above that it will randomly disappear completely for short periods of time and then return.

Other things i was thinking is possible exhaust leak at the manifold?

 

Let me clarify, it taps faster as the rpm's increase but it does not go away above a certain rpm

 

Exhaust leak typically is worst at cold start and goes away after 30 seconds or so.
I think you have a roller on a cam follower that is seizing up or something. I wouldnt ignore it.

 

Yeah that seems like another very common one... just so strange to me that it went from no noise at all straight to very loud tapping... no gradual increase in volume or frequency.
I may be wrong but seems odd that something would seize up immediately and not slowly but im no expert.

 

my guess is it will get worse if not addressed, sometimes you get a warning from parts that are on the edge of a tolerance rather than an outright failure.

 

I certainly am not going to drive on it. Im going to poke around with a stethoscope tomorrow to try to pinpoint the location of the nose

 

One thing that just came to mind... could the spark plug that was loose have been burned up or damaged due to it being loose?
That would also make a noticeable ticking noise no?
My mind keeps going back to the fact that the one plug (on same side of engine noise) that was loose had nothing to do with it?
Seems unlikely...maybe ill throw a new plug in there first to rule that out.

 

Think I found the culprit… now the question is should I replace all 12 while i have it ripped open.