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Discussion Starter #1
after a great deal of effort, we have FINALLY got our 73 450sl to run. now we are trying to take care of the small things. we still have a rough idle and in searching the forum for possible answers i happened on the vacuum thread with diagrams of our system. i noticed that there is an item that we do not have on our system. it is located between the throttle housing and distributor and is called a 2-way valve in one place i read and called a switchover valve in another. our system just has a white plastic tube with rubber ends from the throttle housing to the distributor. does anyone have an actual picture of this item and its location under the hood? the rough idle seems to be reduced when the engine is at operating temp. so i am wondering if this could be the problem. we have replaced most of the old rubber components (fuellines/vacuum hoses/etc). we do not have any info regarding this car from past owners as it was purchased at auction. and it appears as thou someone had been trying to correct some sort of problem in past by by-passing a few things that we now have sorted out. any suggestions or pics would be of great help.

thanx don
 

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That valve, if I remember correctly, serves to adjust (vacuum) timing resulting in rpm increase at idle when a/c is on (compensating for the loss of rpm).

Not at home now, I can check my manual only when I return home in a few days
 

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Does this help? I can provide you with a larger photo if you like, or take a close up of the area your looking at if you would identify the area on the photo.

Loren
 

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Discussion Starter #4
Loren..
can you trace the vacuum line from the distributor back to the throttle body and tell me if there is another valve(inline with the tube) some place in the line? if you have a picture of that, if there is one, that would help me know what it looks like and where to look for it...thanx
like i had said before, someone had haphazardly reconnected things to try and get it running correctly. as an idea of this ...the condenser in the distributor did not even have a wire!!! i do not know how i even made it 40 miles home with it set-up like that...the coil was hooked up incorrect and there was a wire that had corroded thru on the 3/6 trigger points...it ran rough but really kicked butt on the way home when given full throttle... just lucky i guess, but i now have most everything back to sec... thanx for the help.. don
 

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This is about as good as I can do.

The Red line runs from the distributor to a vacuum control (or whatever those things are called) at the rear of the expansion tank, and then from there over to the throttle body (blue line).

I've got lots to learn, but I am trying.

Hope this helps.

Loren
 

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Discussion Starter #6
do you have(or would you take) a picture of the unit that the vacuum lines attach to by the expansion tank?
all i find near the expansion tank is what appears to be the windsheild washer pump.

thanx don
 

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Here are a couple of photos. Hope this helps.

Photo taken from the valve going back to the distributor (red) and throttle (blue), taken from the valve looking back.

The other is of the valve. You should have 2 holes in your expansion tank support, if not, perhaps you have a different setup than I have.

Loren
 

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Discussion Starter #9
that was perfect... with that picture i located the unit.. it had been removed from it mount and tucked back by the battery under the wires.. thanx a million...now to locate a new one...don
 

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Discussion Starter #11
wife has camera with her and she is in germany..
no she's not there for parts althou i tried to get her to look for some she used some excuse about not having any spare time from work for such things...
the pics that lfedje provided look similar to mine but much cleaner...

NormanB...as a kid i lived just north of you in a town called Moss Bluff...is it still there?

don
 

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Discussion Starter #13
i will be down in June/July of 09 to check on family plots.
i know i'm in for a surprise as i'm sure things have changed...
 

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I had someone dick with the vacuum system on my car when they didn't know how to smog it and it was a costly enterprise to get the issues resolved. This is exactly why people MS their cars, you get to loose most of the vacuum stuff.

Once you get the thing together you might consider MSing the car. From what I've read the weak point in the early d-jet was the air sensor or some other sensor that was designed before they had a good grasp of computers.

Good luck!
 
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