My 2002 5.4L 2v was parked for a few weeks while I was out of town. I started it up and definitely sounded like rod knock. Shut it down and checked the oil level, which was fine. Hooked up my cheapo OBDII reader and started it again. Still knocking, everything seemed within normal range, so I got on the computer, to see what I could learn. It appears that many people have experienced this, but not many solutions are discussed. Many people have claimed that they just kept driving them and have been fine for 10's of thousands of miles. A few claimed it was cats and not to worry, etc. etc. One person claimed there was a TSB specifically about this, but I haven't found it yet. Still others claim a rotating mass problem (rod bearings) and failure inevitable.
My truck isn't burning oil, doesn't seem to have a loss of power, and after a couple miles, the knock disappears. I made a test run to St George and had lunch, restarted the motor, and it was smooth and quiet, I pushed it hard, 75 to 80 both ways, no noise. (620 total miles) Once the engine gets cold, the knock is back at startup.
Does this sound common to anyone? Should I be contacting Jasper about a motor?

 

Are you sure its rod knock and not a leaking exhaust manifold? Rod knock will cause loss of power, oil consumption and other symptoms, and doesn't typically just go away.

 

It sounds mechanical, but I'm not sure. I'm getting a cheap stethoscope tomorrow to see if I can locate it better. There are many posts on different forums about this same knock sound, most all about triton engines in F series trucks and expeditions. I was just trying to tap into the decades of experience on this site.

 

For sure. My experience is exhaust leaks can sound a lot like rod knock. Those engines are known for manifolds as well, so it might be worth looking into. Would also make sense as to why it goes away when warm.

 

Could possibly be piston slap.