Idle speed /constant speed control

[Esmo]

Hi My 1967 SL230 automatic,has been set up by a specialist who tells me that the idle speed control 000 072 05 00 has failed and any used ones are not worth it as it’s a common problem . Having checked MB main dealer , SLShop ,SLS all confirm not available . Niemoller in Germany do offer a rebuild 8weeks and over a £1000 including tax exc shipping . My question is does anyone know of a rebuild service in the U.K. ?

[stickandrudderman]

I can probably make yours work again.

[rwmastel]

What you call "idle speed control" is also called "constant speed solenoid" or CSS.  I see you are a full member, so here in the Tech Manual you will find a part number for an interior seal.  See if it is still available.  https://www.sl113.org/wiki/Restricted/Linkage-tour#ConstantSpeedSolenoid

How do these work internally?  They get the signal from the auto transmission and/or air conditioner, then what pushes the rod out?  Is there an electromagnet and spring inside?  I would think a bimetallic spring heated by electricity would not have the necessary force.

[BobH]

Might just be worth testing it yourself, easy to confirm if it's working electrically or not, good advice on this post

https://www.sl113.org/forums/index.php?topic=451.0#:~:text=The%20solenoid%20works%20electrically%20through%20contacts%20of%20the,it%20might%20just%20be%20the%20idle%20switch%20adjustment.

How do these work internally?  They get the signal from the auto transmission and/or air conditioner, then what pushes the rod out?  Is there an electromagnet and spring inside?  I would think a bimetallic spring heated by electricity would not have the necessary force.

it's a solenoid, so, an electromagnet, attracts or repels the pin/rod

[rwmastel]

So, I looked up solenoid and found this basic, easy to understand video:  https://www.tlxtech.com/articles/solenoid-101-what-is-a-solenoid

Why would that fail?  All I can think of is moisture gets in there and corrosion happens.  Any other reasons they fail?  Such a simple device.  Oh, and the moisture issue goes back to what I found in the Tech Manual about a seal.