Focus Problem at 3500rpm

My S reg 1.8 Zetec makes a most disconcerting metallic rotating (schwip schwip schwip schwip) type sound at 3500rpm regardless of gear. Any ideas?
thanks!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@visation.com writes

--
Paul Giverin

British Jet Engine Website http://www.britjet.co.uk
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.