I am replacing some of the soft lines and starting to get to know the vacuum system. I noticed this solenoid valve is not hooked up. What does it do? I see the solenoid above my brake booster on my vacuum diagram but this one in the picture of passenger side of brake booster is not in diagram.

The line coming from the banjo bolt goes straight to the ALDA. Is this valve suppose to be in series with the line?

In the picture you can see no line is hooked to the side hose on top and at look like the top is like a filter and then on the bottom there is not hose connected either.

I also found the hard white line from the side of the ALDA up to the vacuum transducer had been sealed closed. What would this cause?

Thanks,

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85 300D Turbo

Wow, this is like what, our third thread this week on this subject, it's pretty popular I must say. That valve is called the overboost protection valve. In the event of an overboost situation, this valve does not allow the ALDA to deliver too much fuel as a result and the engine will not run away and destroy itself. There should be a line running from the rear of the exhaust manifold to the bottom port on the valve. The port at the very top is capped off, and on the port that points outward, there should be a line running to the ALDA. If the line is clogged, you'll have miserable performance capabilities. I just cleaned mine out this week, my 300D is a lil' pocket rocket now, no longer do I fear pulling out into traffic!

Take a look here.
http://dieselgiant.com/mercedesaldaboostsystemservi.htm

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

Sorry...You got to love repost.

I am alittle overwhelmed with all the great information on this site. I wonder why it was bypassed.

The line coming out of the side of the ALDA up to the vacuum transducer being block cause problems?. I replaced the hose so it is open now.

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85 300D Turbo