I’m wondering if this ever got solved. I have a 2003 Lincoln Aviator with the 4.6L engine. I had the timing chain replaced about 20K miles ago. About a year ago, it blew a spark plug out. I put in an insert and all ran perfectly with zero codes, etc. Put about 5K on it after that. One day, it started ticking away, as described. Sounds like a lifter, but I have difficulty believing this for one reason: It is silent right up to the point that the engine hits operating temperature, then it starts in ticking. If it were a lifter, it would likely be heard when it was cold, or at least get progressively louder up to operating temp. However, this is like an on-off switch. Below operating temp, silent. At operating temp, tick. By the way, the sound is like that of the bearing in a spray paint can when the can is about empty. I wonder if a broken exhaust manifold bolt could result in such a problem at operating temp. Any ideas?