As the title says really, sometimes when i start my focus (1.8tdi) theres a while smell coming from the exhaust. No real wreak or anything but the smell stays for a good couple of mins at least.

What would this be or is it just typical diesel??? Would it be worth while or just sillyness to buy the stuff you see to add to your fel to help clean the system out?

Also, when im sitting idle, again, upon startup, there seems to be a bit of a clanking noise coming from under the hood..Any ideas

All replys much appreciated!