E300 turbodiesel

[pikeyboy]

just wondering if anyone can help as i have recently bought a e300 turbodiesel as my new tow car for the racer and noticed that it makes a funny noise. It sounds just like the expansion tank is leaking when you switch the engine off. I opened the bonnet to investgate as I thought i had a dicky cap or something but he noise seems to be coming from a little black box on the near side inner wing that has a small tube going to the actuator on the turbo. anyone had this problem before?

any info would be much appreciated, cheers stu