On this line drawing , what am I looking at , where is this linkage and adjusting nut. Is this on the injection pump and the two prongs sticking up, is that where ELR plug goes ? I don't know what I'm looking at in the drawing ! I can only hope it could it be as easy as raising the mechanical idle speed. !

OK now I see , I must have got excited and not absorbed the whole post. I will go out and look again. Thanks so much,Charlie

Yeah,well the "Line Drawing" as you call it
Shows a "Handle" on the Mechanical Idle Speed control Shaft (6mm) ,BUT mine
is just a "Naked" 6mm hex shaft.Maybe yours still has the "Handle" ?

Remember, Check your cables and "Doggie Bones" in the control system for ease of motion (proper movement range and freedom),before
adjusting the Idle Speed.

1.Also the engine should be Warm 80 "C" (That's about a twenty minute run)
2.With the ELR unplugged to adjust the Mechanical Idle properly.

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'84 300SD sold
124.128

Even if your erratic idle is later found to be dirty injectors (or Timing) or a weak
lift pump,or a weak return pressure relief valve spring...the mechanical idle is
no big deal to correct.

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'84 300SD sold
124.128

I will let it cool down and try it again. Then I can see if it's better.

At a Minimum.
Then you should be able to just plug the ELR connector back in and she'll idle
on her own...'should be no need to let it "Cool Down".

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'84 300SD sold
124.128

Redline 85 Plus will help clean out a lot of the Carbon built up in the engine's
internal combustion section [AND most Importantly clean your Aged Injectors!]

A Diet of: RedLine 15W40 Synthetic or Royal Purple Synthetic will "clean out"
all the internally lubricated engine parts.

Attached Thumbnails

   

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'84 300SD sold
124.128