knocking/ticking noise in idle and driving

hi all think ive just figured out how to do new thread so here goes

just recently a knocking/tapping noise has accured on my 300tdi disco 97

what i have done is changed both vac pump and fuel lift pump made no difference infact the noise started after that the original noise is still there
too which was a rattling but bin told could b ujs the new 1 is coming from engine more noticable on idle but can still here while driving can anyone help me doin my head in

many thanks

I had a knocking at idle and found it to be my air box (300tdi defender)

ok ill have a look forgot to say that i know that one of the bolts holding inlet man is loose over tightened it n f"!$&d the thread in the block could that contribute