2014 CLS63S SB
Just done the oil change on a 430 and while the bonnet was open and the motor running thought to myself that the tappets were kinda loud. Anyway it wasn't the tappets but a little device that sounds like loud tappets. Looking from the front of the car, (right hand drive if it makes a difference), on thew right hand wheel arch to the right of the ABS unit and behind the washer resevoir is this thing. Fed by two pipes, one goes into the block somewhere and the other drops deep into the engine bay. It has an arrow on it probably indicating direction of flow and the letters 'MOT', couldn't see any numbers.