I have a 2003 MK1 Focus Zetec 1.6 that is starting to make an annoying clicking / clinking noise from the engine. The best way I can think of describing it is almost like a high pitched clinking noise you get when you tap glass bottles together.
When I am in neutral and rev the engine I can't hear it, it mainly seems to happen either when accelerating or in a highish gear going up a hill. So presumably when the engine is working harder. It has done this for a while but seems to have gotten a little worse since it came out of the garage for an MOT the other day. But all they did was change the CAT, brake pipes and things like that. Nothing to do with the engine apart from update the engine management software version (they said it fixed an issue with the engine revving its self slightly which it seems to have done).
Car has done 99K miles and was serviced this time last year so is due another one.