How long ago was crank pulley changed? Was the new one a no name cheap one?
How old is the belt , tensioner and idler pulley?
Is the noise a squeak squeak squeak at idle speed that lessens as revs rise?
Does noise disappear if aux belt removed.
Put a new pulley on and run some he car to have he same noise, noise made is just the same as when the crankshaft pulley goes(clattering)it does get a bit quieter when under load, didn't know you could run it with the aux belt removed
Run engine without aux belt fitted, if noise gone you know for sure it's something driven by the aux belt.
If noise still there then it's nothing to do with aux belt.
You may want to check crank bolt isn't loose.
