So my '04 Disco engine has been "chirping" at me for way too long. The noise occurs whether the vehicle is in park, reverse or drive and with much greater frequency when I accelerate. It had been awhile since I replaced the serpentine belt so I figured this was the culprit. I changed the belt (it was in pretty bad condition) but was greeted once again by the chirping. So I did some further investigation, localized the sound to the region of the a/c side idler pulley, replaced it with a new one (job took 16 minutes to complete) from DAP-inc and now am chirp-free! My understanding is that this is pretty common for the Disco. esp. older models that had plastic pulleys (I think these have been recalled and LR is replacing).

Yup... my experience is idler pulley and the tensioner for said chirping. I was next to another Disco the other day in traffic - that guy needs to read this post! About cracked my windows it was squealing so loud!

My 03 is chirping when it first starts... idler pullies are gonna need some love soon. It's just too damned cold to deal with right now.