Gearbox noise after new clutch and gearbox

[Leighk9]

Hi guys, so my differential went bang and put a hole in the gearbox housing on my 2014 vw caddy 1.6 tdi so I sourced a 2nd hand box which was allegedly from a 45k van, I also fitted a new luk 3 piece clutch whilst I was at it, the flywheel looked to be in good condition so I left it in, put it all back together and now there is a whirring noise at idle in neutral and when I push the clutch pedal down the noise gets quite a bit louder. This noise wasn't there before changing the box, can anyone shed some light onto this as I'm beginning to pull my hair out with it.
It drives fine and sounds fine whilst driving but I guess I just can't hear it over the engine noise.

Thanks

[Doc]

What you describe sounds to me like the dust shield between the engine and gearbox is warped and rubbing. This happens a lot and can often be resolved by manipulating the shield through the holes in the bell housing.

[BenT]

I had exactly what Doc's just described. I was convinced that I'd lined the dust shield up correctly, but could hear it scraping after my clutch replacement. Was much worse on sharp turns for some reason. I just left to, err, resolve itself naturally and 10,000 miles later it was silent

[Leighk9]

I'm so relieved you guys said that because that's the only thing I could think of myself. I know as I was trying to squeeze the gearbox back in the drivers side driveshaft flange was rubbing on that dust shield and probably did move it out of alignment. I mean the van drives sweet as a nut but that noise is so disheartening. I'll leave as is for a couple of weeks if it goes quiet then happy days if not I'll whip the gearbox back off and take a look. Thanks again for putting my mind at rest