On top of the intake manifold, towards the back there is some type of solenoid or check valve that is black and has a connector on top of it. What is this part. The wire connection that goes to it won't stay fully seated, and I was wondering what harm if any, is being doen by this. Thanks in advance

Is this what you are referring to?


http://www.mindspring.com/~houlihan/merc/banjo.htm

No that's not what it looks like. Since I first posted the question, I found out what it is. It is a pressure switch. I found it in a diagram of the turbo system in a Haynes manual for the W123 chassis. It has something to do with over-pressure protection. On my car, the wire connection is just basicly sitting there. I tried to push it down in place but it doesn't want to lock down. I am a bit concerned that since the connection isn't a good one, that what ever signal it's supposed to send isn't being delivered to where it needs to go.