BlueOutThwLighy

What is this sound related to? I have changed injectors a year ago and glow plugs a month ago The noise started recently and got louder by the day It's unbearable now and always there whether Im in idle or driving, a few second I hear then stops then back I initially thought it was just a brake disc as it is more pronounced when coming to a full stop but as I opened bonnet I am hearing it from front/front left of engine mainly I stopped driving for now Engine oil always changed in good time using Castrol Changed cambelt&waterpump at 70-75k Mileage: 105k miles No warnings on obd2