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'91 300 2.5
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I have just entered the world of MB with a '91 300 Turbo Diesel that has a few quirks and gremlins, so I hope I can get some help from you all.
I am also totally new to diesel, so I'm sure I'll ask a couple totally idiotic questions.
Anyway...

There is an airway between the turbo and the intake that has what I assume is a vacuum operated butterfly.
When I goose the throttle, there is no movement, nor is there any vacuum in the hose.
I also noticed an electrical gizmo on the vacuum canisters...is it possible that the vacuum only works when the car is in gear and driving?
Thanks in advance
 

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83 300CD, 07 ML320 CDI, 04 WRX, 86 300D (totalled by my neighbor), 85 300D (sold)
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875 Posts
If its anything like the 87 300D turbodiesel - that actuator you mention is the boost control actuator / aka wastegate actuator. And yes it moves when you goose the throttle. Another way of testing is installing a boost guage in your intake manifold. It should go to at least .85 bar when you floor it when you accelerate and reaches 4000 rpm.

Im actually fixing this problem right now because mine is also not working. There is a hose that runs from the turbo to the actuator and mine is cut. Air is leaking and it sounds like a jet whenever i accelerate. I thought it was the turbo working - but in fact it was the turbo leaking !

If your alda works perfectly. You should see significant gain in hp after you fix that problem.
 
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