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80’ 450 SL
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Discussion Starter #1
I just purchased this vehicle and it idles a little rough so I removed the air cleaner to check the vacuum lines and I found one that does not have a place that I can see to connect, I am not sure what it is and if I can just block it off. I haver attached a photo.

Thanks
 

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'79 450SL, '04 CLK200 convertible; former A124, W210, A209.
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1,407 Posts
This one ought to be connect to auxiliary air valve I think, at least so is my 1979 450 - see the pic. Connecting the two should improve your idling issue.
2617634
 

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80’ 450 SL
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Discussion Starter #6
That vacuum hose goes to inlet manifold . View attachment 2617638
I cannot find an open port on the intake or a disconnected hose, but I do see a port capped off at the front of the intake manifold. I am not sure why it is capped off, but is that the likely connection point for the WUR? Photo attached. I am hoping the WUR was not disconnected because it is not functioning as it and the air mixture valve are expensive parts to replace Is there an on line service repair manual I can access for this 80 450 SL where I might have rebuild instructions for these parts, if I still have idle
IMG_3613.JPG
issues?
 

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80’ 450 SL
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Discussion Starter #8
The little rubber elbow is just a vent to atmosphere, it is not supposed to be connected to anything.


View attachment 2618213
Thanks, the car still idles a little rough when that elbow is connected to the intake port that had been capped off. The elbow has a white chalky residue in it. I installed new plugs, cap and rotor. I am thinking I need a new warm up regulator. i don’t know how to test it and I hesitate laying down the cash they are asking for a remanufactured if I’m not certain it needs replacing.
 

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'80 450SLC Afro RHD Ikonengold
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^ ^ ^

You may become confused as there were few versions of WUR with various connections appearing similar but not the same

Most important is to quote the WUR part number (embossed) and from that you can see which type of the WUR you have.

1980 was a mixture of shifting K-Jet towards what will result in KE- Jet and some world regions adoptation of different pollution management systems resulting in variety of vacuum stuff appended to the engine.
 

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That vacuum line is for acceleration enrichment, I don’t think having it disconnected will effect idle too much. You can get these engines to idle cleanly with most of the vacuum lines plugged.


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