ticking/tapping

Hi all I have a strange rattle/fast ticking noise somewhere in the engine bay when I take my car out of Gear (D) then into park (P). The ticking slowly reduces in 10 seconds and then is unnoticeable and continues to run normally again (Diesel engine noise) have any idea what it could be? cheers.

Hi all, First post so please be gentle :) Bit of brief background, I owned a w204, used, 6m old, 4k, coming up to 4 years ago. Had to sell due to change of circumstance. Been in love with Merc ever since. Fast forward to mid to late 2018, suspected epilepsy, obv couldn't drive. Last month...

I have scoured the forum for suggestions but haven't found a lot for W202 specifics, so am hoping people might have some advice. I picked the car up, fairly cheap, a few weeks ago. I could tell it wasn't perfect but the money was right, it had good history and only 120,000 miles, so I went...