Hi all I have recently bought a project insignia, it drives absolutely fine but has a rattle knocking sound coming from somewhere in the engine bay, I’ve had a few different ideas thrown my way one being the DMF, possible injector leak, servicing due and pulley bearings (unspecified) 

Hi....welcome to the Forum

I would first start with removing the auxiliary drivebelts and run the engine for a very short period to see if the noise disappears.

Sometimes a crankshaft pulley that is breaking up can give this sort of noise and is a very simple and cheap fix.

If not, then refit them and nothing lost....then time to move onto the bottom end.

Thanks, ile check that iut first before moving onto anything bigger, thanks for you help 👍