Chirupping Noise!

Hi, My 90 sounds like what as I can best describe as a big bird under the bonnet chirupping away.
It seems worse under load and I'm hoping someone might know what's causing it and will it result in any damage if i keep driving it?
I had a new steering pump belt fitted last week and wonder if its something to do with that, also the power steering seemed to 'go' tonight driving home - maybe its related or maybe just the extreme cold, it also made a bit of a noise when turning.
After a full service last week, I thought i'd finally sorted everything out :-(
As always, any advice greatly appreciated.
Cheers
Andy

viscous fan or one of the pulleys. or could be the belt but more likely the pulleys.

is it a 300TDi - search for "penny trick"

oops 2.5 doozil. .

Had the same on my 90 turned out to be prop ujs, if it only does it when moving worth having a look to see if there is any play.