Nikos your engine sounds normal.
My engine was always tappety when you open the bonnet. The exhaust note tells you how smooth the engine is running.
Mine sounded like that when it ran ok.
When it became bad you could see the engine out of balance with the vibration.
If you opened any door/bonnet you could see how bad the poor idling was.
New Company car 2011 BMW F10 520D SE Xirallic Imperial blue/Cinnamon Brown 6FL USB, Front Sports seats, Sports steering wheel, Xenons - Arrived 3rd Dec 2010!
Scrapped RIP 12/08/2010 - E90 320si - Le Mans Blue - Totally standard specification
Long gone - 00 Peugeot 306 2.0 SE Cabriolet, 94 Rover 214 SEi, 91 Fiat Uno 60S Mk2