Is this some kind of idle control knob? 81 240D

Mine appears no to be working

My manual is on it's way from Ebay

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Thats an idle adjsut knob.....should allow you to raise idle to about 1,200 rpm...down to whatever the IP is set for....

older W123 and W116 diesels have it...but not the newer W123 cars (E.G. my '83 300D doesn't have it, but my '79 300SD does)
Cable is either misadjusted (too much slack) or broken.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Anyone have any idea why the W126 300SDs and later 123 300Ds did not have this knob on them? They certainly would be better than having to go under the hood and do idle adjustments.
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

Probably because most of the ones you see are broken like bennett's

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BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif
15 VW Passat TDI
00 E420
98 E300 DT
97 E420 Donor Car - NEED PARTS? PM ME!
97 S500
97 E300D
86 Holden Jackaroo Turbo D
86 300SDL
(o\|/o)

I use it on my w115 as more of a choke function than an idle control. When it's cold it makes starts a lot easier. Once it's warmed up it's cranked down completely to normal idle.

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1974 240D 3.0L 4(M) - 250K -OM617.910 + 300D FW + Rajay turbo power!
1977 6.9 3(A) - 84k

I figured this out reading a thread here describing how to start a diesel properly, once I got my cable adjusted (my indy) and the little knob replaced (cracked plastic from the PO).

Don’t try to rotate the knob (counterclockwise to increase idle speed) on its own, it will be hard to do and may break. This is especially true if it’s cold out, which of course is normally when you want/need to use it. If you push down the diesel pedal about half way, then turn the knob, it rotates easily, with no strain on the cable or the plastic knob. Release the throttle, and start ‘er up. Great thing to do while the glow plugs are heating. Returning it to the low idle speed position (clockwise) can be done as needed/wanted with no strain on the system.

Great little device for the morning warm up, while you run back into the house to top off the coffee.

Happy motoring,

Clay

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2002 E320 Sedan 93K Designo Mocha Black Metallic!
1995 E320 Wagon 205K Black Wagon
1982 240D 183K SloPoke

I believe each of these cars are the final production year for that model.

I don't think the w126 and later 300D's had it becuase they don't need it?
Mine seems to work great in cold weather and seems to idle faster when its cold out.
Iono..
The less knobs and the simpler drive the better it seems in the w126..less things to confuse the drivers with that "new fangled turbo diesel engine under the hood"
A new breed of drivers?

so if I understand correctly you just turn in clockwise a 1/4 turn for higher ilde and back counter clockwise to defaiult?

it's not a full rotation thing ..right..that will break it?

You turn it counterclockwise to increase idle speed and as one post has correctly stated better done with pedal depressed a little to remove load. After car is running then reduce idle speed by turning clockwise. Since mechanisim is unloading there is no need to depress pedal for the second function. My daughter borrowed a 300d from me last summer and had a few problems as logic seems to increase idle function one would turn knob clockwise but the reality on mercedes is different. Oh yes the control endpoints are well pronounced and probably about 120 degrees apart but the distance is only an estimate from memory. I always just go to the respective endpoints when using the control. Just try to remember to depress pedal when turning counter clockwise to lessen possible knob and cable breakage.

...I was just going to pompously hammer out why this knob was only installed on earlier models...and I realized that there was a major flaw in my logic... .
Anyone know why for real?!?!

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Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress

in wis. it is very functional for winter. in utah??????? you tell me. OBTW don't forget to turn it down after a few minutes otherwise the car runs strong and fast and drinks fuel.

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currently
[1981 300 td tdidi 165500 dark brown/palamino-Brownie-mine-3k miles of ownership
1983 240d 162+++ Anthricite grey w/ henna red interior and hella lights-wifes car-Red

the above two cars are for sale
and can be seen on the cars for sale thread here. pix also available.


240d-144+ Manilla Yellow w/ palmino interior-greasecar kit-Blondie-the college kids car

23" gt 21 speed still on original tires-still got the nubs
21" khs tandem

Utah is high desert but we have 9' of snow 15 miles from me at Sundance Ski Resort... it's not Wisconsin but it get Cold.

That little knob is another one of the fun things about my '82 240D...

I'm always "tuning" it - just a click at a time - to get my idle "just right"

Seems like the perfect idle for me is 4 clicks away from the clockwise-most stop.

- Patrick

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1982 240D. 198k, Marine Blue/Blue, 4 Speed, Crank Windows, No Sunroof, No Rust, No Oil Leaks
2001 TDI. 197k, Lagoon Blue/Black, 5 speed, Chip, G60/VR6

Mine was not working until I adjusted it at the motor bracket. I also sprayed some lubricant into the end of the cable and into the little box behind the knob. I use it only for cold weather warmup and turn it all the way back for normal idle. If your cable continues to turn hard you can remove the plastic clip that puts a kink in the line. That reduces friction makes it easier to turn even with the pedal depressed.

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Bill Reimels
Now down to one:
1972 300SE 3.5 W109 (Euro delivery)

I had replaced mine on the 240, It broke on me going home on the interstate one day, the car lost speed quick and I had to pull off quickly, there was a lot of traffic that day. Had a top speed of about 20mph the rest of the way home. After replacing it, what a difference, it turned so easily

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1980 500SE/AMG Euro
1981 500SEL Euro
1982 380SEL
1983 300TD
1983 500SEC/AMG Euro
1984 500SEC
1984 300TD Euro
1986 190E 2.3-16
1986 190E 2.3
1987 300D
1997 C36 AMG
2003 C320T 4matic

past: 1969 280SE 4.5 | 1978 240D | 1978 300D | 1981 300SD | 1981 300SD | 1982 300CD | 1983 300CD | 1983 300SD | 1983 380SEC | 1984 300D | 1984 300D | 1984 300TD | 1984 500SEL | 1984 300SD | 1985 300D | 1986 300E | 1986 560SEL | 1986 560SEL/Carat | 1987 560SEC | 1991 300D 2.5 | 2006 R350