Ok so I am currently having this same problem. Does anyone know what the issue eventually turned out to be?
Skoda fabia 1.4 tdi pd engine. 2008. Currently at 222k miles.
I have a rattle at ideal. Raise the revs and it goes, press the clutch in and its gone. If the engine is kept at around 1000 revs no sound at all. Drives fine.
I have uploaded a video.
https://youtu.be/Z4CMXIXudgA
I did get cheated when I bought the car as I realised it was there only after it got home. Anyways thts a different story.
Its been around 12 k miles now since I bought it. I think it has got a little worse as first there were some instances where it would stop comming if I pressed the clutch n left it. But tht does not seam to work now. As soon as the rpms go down to around 800 it starts rattling.
I have changed the gearbox oil, tried adding some additives in the box but no difference.
Any advice is much appreciated.
Thanks in advance.