BMW Repair Questions? Ask a Mechanic for Answers ASAP
I'd first try removing the auxiliary drive belt and turning every pulley and ancillary ( power steering pump , alternator etc) by hand. All should turn easily (with the exception of the AC pump) with no grittyness or wobbly pulleys- If you do find a sticky pump / alternator then it should be replaced or repaired
If the engine is stone cold you can briefly run it with no belts to see if the noise changes or has gone away, this will help show if an ancillary is the issue
Examine carefully the condition of the bottom / crank pulley as these are composite construction with a rubber element and its possible this rubber is breaking up and allowing the two metal portions to move.
Another possibility is the variable valve timing system as this does rely on oil pressure to correctly synchronise your vvti pulley on the end of the camshaft. If the valve has become blocked up then its possible the pulley is rattling about and producing the noise.
Tried all that today, didn't work unfortunately. Do you think it could be injector knock? Or maybe something to do with the swirl flaps?
I know it's the exact casterol gtx oil that the handbook says to use! When he disconnected the injectors I don't think he took them rite out, he just Un plugged them! Can I upload a video of it maybe?