307 hdi 90 occasional ticking / cracking

[p.sharp]

first of all im new here

secondly,

sorry if this has been asked 1000 times already...

i have a metallic squeaky type sound upon start up (from the bottom of the engine) then once the engine is warm turns into an intermittent tick / crack, this noise dissapears when the throttle is pressed slightly.

The noise sounds like a cracking sound rather than a tick and comes back at around 1500 rpm (and is a constant sound rather than intermittent - almost like a tappet sound but obviously from the bottom of the engine)

also, i sprayed wd40 on the pulleys etc which gets rid of the cracking sound for around 5 minutes or until the engine is revved high.

After reading around the net etc i'm leaning towards a pulley of some type, so i may have answered my own question - LOL

anyone had these symptoms and can specifically pin point my problem? or had this problem & eventually sorted the noise?