Rattling noise - spring in intake?

[Mattt]

My car makes a slightly rattling noise at low revs and when cold, the dealer said it was a worn spring in the intake system (or something like that), ordered the part and said it's 4hrs labour. All covered under warranty, but does anyone know what it actually is?

3.0i by the way.

 

[Curtis]

Could be an inlet valve spring, I've never heard of one rattling before though unless it's snapped. When that happens you tend to loose the collets that hold the valve in place and the valve "drops" leaving you with lots of engine damage! Based on that a broken valve spring doesn't seem likely but I can't picture any other spring in the intake system.

 

[Adam D]

Not something to do with the intake system which has a flap to shorten/lengthen the tuby bits.

I could be talking nonsense mind...