Solenoid for Increasing Engine Speed (on top of inlet manifold)

[Klaus Pieper]

Hello,

Under normal operating conditions and also under test conditions, the pin of the solenoid on my 230 SL extends by 2-3mm, not enough to increase the engine speed sufficiently so that the engine does not die, when changing gear from P or N to another gear.  When pulling the pin by hand it extends by 6mm.  What is the "normal" distance by which the pin should extend and would you have a suggestion to remedy the situation? 

[Pawel66]

There should be marking on the solenoid housing, stating the distance. It is 5mm on mine.

If the travel produced by your solenoid is not enough even though you tried to adjust the length (the nut is adjustable) and if some simple cleaning is not enough - there are posts from Members who dismantled this solenoid (cut on lathe I think), but you need to read it through and judge if it is worth the effort.

https://www.sl113.org/forums/index.php?topic=27065.msg193973#msg193973

The replacement is available but expensive. You can try ebay for used ones.

Perhaps 2-3mm would be enough if the engine is in perfect tune...

[Klaus Pieper]

Thank you very much Pawel for your quick response.  My solenoid also shows 5mm - I don't know how I missed that.  I will try and find a way to clean and lube the inside of the solenoid and then take it from there.  At 754 Euro, a new solenoid is rather expensive but beggars can't be choosers.
Regards,
Klaus

[Pawel66]

Maybe it just accumulated some dust there on the shaft - there should be a rubber cap on the shaft to prevent that, maybe it was missing.

If you need to buy - try this forum. Also: these solenoids were installed on some cars without being connected. Some owners have them but do not need them. Maybe you will get lucky.

[stickandrudderman]

  I will try and find a way to clean and lube the inside of the solenoid and then take it from there. 

Search this forum, there is a way to repair them

[Klaus Pieper]

Thank you all. I tried to clean the solenoid using contact cleaner, but to no avail.  The next step, if I can muster enough courage, is to try and repair it.
Klaus

[Shvegel]

Klaus,  I wrote the repair post that involves drilling the back of the solenoid and using a punch to free it up and I think I have an easier and better way to repair the ones that still have some movement.  Try removing the nut and threaded plate from the rod, put 2 nuts on the rod (5mm?), tighten them against each other then chuck the nuts into a drill so you can spin the rod.  spin the rod at medium slow speed and work it in and out at the same time.  That should break up the corrosion.  The rubber boot is still available and I suggest buying a new one before they are no longer available.   

[Klaus Pieper]

Thank you Shvegel for your suggestions.  I have given it a go, the pin moves freely forward and backward and also spins very easily.  However there is not enough power to move the pin the required distance of +- 5mm.

I will open the solenoid and take it from there.  Could it be that the armature is damaged?

[Cees Klumper]

My original solenoid has the same issue. It is free, spins etc but no longer has the 'oomph' to move the linkages. Bought a new one when they were still at least somewhat reasobably priced, but kept the old one to try and repair at some point.

[balimatharu]

Related question.
250sl. The solenoid works fine when I use reverse gear.
There is no response from the solenoid when the lever is engaged in drive.
Can someone pin point where is the problem.
I would be grateful.
Bali

[Benz Dr.]

There are two pressure switches on your transmission and one isn't working. Also, check the wiring in case there's a problem there. The fact that one works, indicates that the system is operating but only on one switch.

[balimatharu]

Benz Dr.
You were right. There was a connectivity problem. The wire that connects the right pressure switch ( forward drive ) to the left switch ( reverse) didn’t make the contact. Cleaned the terminals and all working well. Now need to do a road test.
Thanks for the tip.
Bali

[Shvegel]

For anyone searching this later with a bad switch I am pretty sure one of these will work.

https://www.ebay.com/i/302640097936?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=302640097936&targetid=935694488106&device=c&mktype=pla&googleloc=9051739&poi=&campaignid=10877145294&mkgroupid=110621922841&rlsatarget=pla-935694488106&abcId=9300400&merchantid=8295724&gclid=CjwKCAjwoc_8BRAcEiwAzJevtd0f9XdBeo71L9U2j5JaGe-ekg4GdylOBEhDhQKc65qWm73iZPdSKBoCYsYQAvD_BwE

[Pawel66]

Thanks for this!

Original are very expensive!

[mnahon]

I looked around online, and as best as I can figure, the original has a switching pressure of 1.6 kp/cm2 which is 1.57 bar, while the one on the ebay link has a switching pressure of 0.2-0.5 bar. Do you figure that difference is OK?