I believe you have a 5.4L 3-valve. These engine are variable cam timed. The camshaft sprocket is a spring loaded, oil controlled unit that is not servicable. They have a history of making noise. Ford states that there are three levels of noise. Th first is a light tick that occurs at idle and on cold start-up (as you described). It is not damaging to the engine and will not (at this stage) affest engine performance. The second is a tick that is present at any time the engine is running and at any RPM. While it is still not damaging, it is recommended that it be replaced. The third is accompanied by a miss. At this stage the cam phasers have adjusted the cam enough for the piston to smack the valve. This usually leads to complete engine failure. I have performed all three levels of repair to these engines and my personal recommendation is to leave it alone, but monitor it for getting worse. It will not jump from stage one to stage three. If it gets worse or you just want it fixed, have it done by a dealer. These engines are VERY sensitive to timing procedure. They are relatively expensive to replace. That's why I recommend leaving them for now. If you have any further questions, feel free to ask. I'd be glad to help.
Sunday, January 20th, 2008 AT 10:05 PM