W210 - vacuum leak/tick part question
 

OK, what's the black vacuum part in the right of the attached picture, above the windshield washer reservoir and to the right of what I guess is an anti-lock brake controller?

When I park the car, this particular part makes a noticeable fast ticking sound, which tapers off and then stops after a minute or two. Obviously the part has something to do with vacuum, but I have no idea what. The car is mostly behaving fine, though sometimes when I open one door after parking and killing the engine, the remainder of doors do not automatically unlock. If I hit the button on the console, they work without fail.

Just curious what this part is and whether its sticking is normal. The number on the cap is marked "A0005450427." If replacement is necessary, is it expensive/difficult?

Thanks for your expert tips --

Cheers, John

My car has the glow-plug relay there and no vacuum transducer. But when I shut my car off, there is also quite a bit of noise produced by one of the transducers under the hood. It surprised me the first time I shut the engine down with the hood open, but I don't think it's abnormal.

The door locks are run by the PSE pump under the rear seat, and not related to the vacuum running to anything under the hood.

if you have the part#, just run it.....it's a transducer, but I can't tell you for what.
you can xcheck this against the Russian parts diagrams/list

http://i9.tinypic.com/4xkzlnd.jpg

I dont know what it does but I can confirm it does indeed make a lot of ticking noises for a few minutes after shut down occurs.

That is a vacuum transducer which controls the EGR valve. There is another one on the right side of the car which controls the turbo wastegate actuator. They do make a sort of bleeding off noise for a minute or two after shutdown so that is normal for them, at least it is on my car.

The one on my wastegate actuator went bad about 18 months ago and threw a check engine light and the car drove very lethargically. I replaced it and all was fine for about a year and I got another CEL, same code, accompanied by the same loss of power I got the first time it failed.

This time I only replaced the small filter element which is on the end of the bleed line (on both the EGR and wastegate solenoids) and reset the CEL and never had a problem again. These transducers are not difficult to replace, they cost about $120 as I recall and the filters are just a few dollars each. They are apparently very sensitive to that little filter getting constricted so if you ever get a CEL code indicating one has failed, replace the filter first and see if that doesn't clear it up.

Thanks for the explanations and personal experiences, guys. It sounds to me like it's normal and I can ignore it for now. I was just a little nervous about what sounds like a vacuum leak, given all the vacuum talk around here!

Thanks again for the help --
Cheers, John