I think I have phaser knock on my 2006 FX4 5.4L w/134,000. I hear the knock in the front area of the passenger side valve train. The thing is, all I have read/viewed has been that phaser knock is only when hot and not cold? I hear it from when it is started up when the idle returns to 600rpm of so. If I give it any gas and get it to 1000rpm, it goes away...which leads me to believe it isn't a lifter/roller follower. Runs fine and no rattle on startup. Is phaser knock on a cold engine possible? its no worse when its warmed up, pretty much always the same level of knock sound at low rpm.

 

Not chain slap?

 

no, definitely a tap and not chain. doesn't change whether the engine is hot or cold, so not an exhaust leak either.