Had mild, intermittent noise for about a month. Sounded like pinging, but happened at 2000 RPM under no/low load. Tonight, started car from cool and got a quite loud chattering/chirping constant noise from 1500-2000 RPM upwards. Getting worse, now constant from 1000 RPM up, and starting to happen at idle. Sounds like coming from front passenger side of engine, just below manifold: maybe timing chain or tensioner, maybe belt tensioner, maybe air con compressor or clutch, maybe bad injector?

Anyone else encountered it? Is it likely to cause a breakdown? or just a major annoyance? Thanx all.

occasionally i get a lil bit of a "Chattering noise" from my 4.0 six... its the timing chain...but unless heard in person at your car its a guessing game as could be a few things as you have suggested..

Took it to the Ford dealer. He found it in 5 seconds. The rubber in the crank pulley/damper is letting go, so the belt is rubbing against the tensioner arm (doh!). Ford wants NZ$680 for the pulley and belt. Found them at BNT for NZ$250.