I have a 93 300d and it has been working great and yesterday i started it and it started fine ,thirty seconds later it quit. I notice the smoke when it started to die was black , I had my sister start it while i was looking under the hood, I saw that the valve on the turbo intake side was getting a vaccuum and closing off which choked out the motor ,i opened it manually and the car ran fine .I traced the vaccuum line to a small valve with an electrical plug on the top of it ,is this a solonoid and what is it suppose to do when it works properly. Could it be this simple just replace it with a new one .thanks

I don't know that system but check if the actuator holds open when you apply a constant vacuum and check if you get a constant vacuum through the hose. If so, the problem is not with the actuator or the switching valve.

Sixto
87 300D

yes the valve will close and stay closed I just wish i knew the name of the part either the valve or the actuator so I could do a search of the forums, i had an 87 300d as well but I do not remember how the turbo was set up on that car. The valve would close and cut the air supply to the intake and this is why the engine would stop, and it would take about 30 sec for the vaccuum to build which closes the valve . I am curious as to how that actuator works under normal cicumstances. When would it close this valve of partially close it .

There is no valve in the inlet of either of your diesel mercedes, either the '87 or the '93, that can close and shut off the air supply to the engines. Are you observing the operation of the wastegate in the turbo? That will allow air to bypass the exhaust portion of the turbo and not generate significant boost, but it won't stop the engine.

Take the crossover tube (cast aluminum tube over the valve cover that carries air from the turbo to the intake) off of the engine and start it, see if it idles normally. If not, you have a fuel problem, not an air problem.

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Gone to the dark side

- Jeff

My '87 190D OM602 has a valve in the inlet. It is normally open. It closes under certain conditions to create sufficient vacuum to allow drawing exhaust through the EGR valve. It is controlled by one of those rectangular black modules, two temperature switches, and a few switchover valves. I'd expect the 300D to have a similar system, but I don't know that for sure. If you disconnect and plug the vacuum line, the valve should stay open and allow you to use the car. The EGR system will not function properly, and I like to have it functioning (trying to do my part....) You may not care, in which case there is no detriment to the car by disabling it.

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1987 W201 190D

I'm pretty sure 300D 2.5s have a flap right at the compressor housing as JonL describes. Items 99 and 100 in the attached vacuum diagram though not named in the listing.

I don't know if default is open or closed but I imagine the ECU is smart enough to it's jammed open and cut boost. Won't be a problem in a 190D with pressure actuator.

Sixto
87 300D

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My 190D is a non-turbo, and now I realize that it is likely a very different system. If the 300D has EGR, it needs some mechanism to create intake manifold vacuum. In the NA 190D 602 engine, there is a butterfly valve (like a throttle valve) in the airbox between the air cleaner and intake manifold runners. It makes sense that on a turbo, the valve (if it exists) would be on the inlet to the compressor so the compressor isn't working against the valve.

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1987 W201 190D

90-93 300D 2.5 might have such a flap. 87 300D definitely doesn't have a flap. No means of creating manifold vacuum. Has to rely on higher exhaust manifold pressure than compressor outlet pressure.

Sixto
87 300D

It's closing off your engines "Fresh" (Boost) air flow.To allow Nasty Dirty
EGR system Exhaust into the Intake instead.

This is the Permanent Solution:

http://www.peachparts.com/shopforum/showthread.php?t=212097

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'84 300SD sold
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