Frozen constant speed solenoid

[awolff280sl]

The CSS attached to the throttle linkage bracket on the intake manifold is frozen. Ultimately I may find that I don't really need it once my rotary compressor A/C is functional and if it doesn't drop the rpm's. Nevertheless, I'd like to fix the solenoid anyway. There are 3 small screws on its faceplate that need to be removed to gain access to the "innards". But removal of these screws appears to be blocked by little flanges of metal. Do I drill them out? Has anyone done a DIY on one of these solenoids?

Andy
Sarasota, FL

[Jonny B]

There have been a number of strings on this topic. Try the search function and use "CSS" or Constant Speed Solenoid to try for matches.

Here are a couple I found.
http://www.sl113.com/forums/index.php?topic=6305
http://www.sl113.com/forums/index.php?topic=8215



Jonny B
1967 250SL Auto

[awolff280sl]

Jonny B, thanks. Iread those links but I was wondering if it could be a DIY?

Andy
Sarasota, FL

[Cees Klumper]

I believe I read about someone taking one of these apart to fix some years ago. Probably worth a try since they are expensive (over $500 I think) new.

[pauldridge]

I had no luck getting to the "innards" of my solenoid, in spite of attempting to drill out as you suggested.  However, I did finally get it freed up, and operational again, by just soaking the shaft in penetrating oil for about a week, then I put the shaft in a vise and managed to turn the body to free it up.  Once free, I found by spending some 15 minutes or so exercising the moving shaft did the trick.  Good luck

[Longtooth]

dumbo question... how would one know that the Constant Speed Solenoid is "frozen" (or othewise not functioning) or not --- on a manual tranny with A/C?

[mdsalemi]

quote:Originally posted by Longtooth

dumbo question... how would one know that the Constant Speed Solenoid is "frozen" (or othewise not functioning) or not --- on a manual tranny with A/C?

Quite simple, actually...when you engage the a/c (and thus put a load on the engine) the CSS is supposed to maintain (it isn't perfect though)the no-load RPM's.

If your RPM's take a noticable drop when you have a load on the engine, now it becomes the two-person task:  open the hood, and engage the load (either put the car in a drive position for auto or turn on the a/c for manual). Have someone look at the CSS.  You should see it engaging/disengaging as you add/remove the load.  By engaging, you see the plunger push out a bit; disengaging, it pulls in.

If it isn't doing it, don't automatically assume the CSS is at fault; now it's time to check the voltage at the CSS to see if it is getting the power to engage.

[graphic66]

Working from memory here. I think the CSS is supplied constant positive power with a switched ground. It can be a little confusing to test because it will show on your test equipment as always hot. I hook the positive test lead to the + battery and the negative lead to the negative pole on the CSS to test it. Now for my question, if you have AC and an automatic tranny how do you get it to engage when the ac is on. I have thought about adding a relay to switch the ground on to the css when the ac is on. Has anybody done this? This of course would kick you idle up when the ac was on and you were not in a drive gear. The ac causes the idle to drop a little when engaged and actually a two stage CSS would be perfect for the auto transmission.