Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: mnahon on January 08, 2018, 00:54:02
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I'm wondering if anyone here has taken apart a constant speed solenoid (CSS), also known as 'lift magnet'?
I have a CSS that half-works. When energized, it starts to extend, but then binds. My impression is that the shaft may be bent, so I'd like to take the CSS apart. However, there's no obvious way to do this. I was wondering if someone here has done this before and could give me some guidance. I could post pictures of where I'm at if anyone figures they have an idea.
Thanks,
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Disassembly is possible but re-assembly is not!
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Disassembly is possible but re-assembly is not!
Sounds very, very familar to me on a lot of fronts...
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New these seem to list at over EUR 1,000 - but in Niemoiller's catalog it appears to refer to these as 'rebuildable' meaning you have to pay them EUR 1,000 as well as return your old unit. I recall a long time ago a discussion on here where someone may have reported having succeeded in rebuilding one, but I am not sure.
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See my post Dec. 23, 2016
I disassembled it, repaired it and it has worked since
Attached see pic of disassembled solenoid. There is a brass washer for a stop and I replaced it with a thicker one. Works fine now - no stickum. Current draw before modification 1.02 amp, after installing thicker washer 1.03 amp
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This is encouraging! I found your Dec 23, 2016 post and read it through. I think my solenoid has a different problem than yours, but irrespective, disassembly is where I need help.
Here are some pictures showing where I'm at. In the first picture, I show an end view showing the only place where I thought there were options for disassembly: there are three set screws. Each set screw is restrained from unscrewing by two tabs. I managed to remove one set screw by using a Dremel to grind out the restraining tabs, and then unscrewing. But when I look into the hole, it's not clear to me what these setscrews do, nor what I may be able to do when I remove the two others.
But now, when I look at your picture, I realize that you attacked the other end; not the end with the set screws. So my third picture shows that end, and it's not clear to me how you got that end cap off. Any pointers? Thanks in advance.
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Going by memory: I put it into a lathe and cut the swaging. The screws hold the coil. Leave the screws in place. The plunger can not come out of the back, it is prevented by the nut. To replace the swaged cap I put aluminum adhesive tape over the opening.
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IIRC Thierry du Laos also successfully opened and repaired his CSS, some time ago.
Regards
Chris
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Thanks for the responses.
I've just sent Thierry a PM to see if he can join the thread. Depending on what he says, we can see if using a lathe is the only way in.
It may take me a bit of time to get access to a lathe.
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My guess is, as opposed to Niemoller or others, maybe a custom made solenoid might be less costly. Indeed, maybe some of these folks have built similar sized and powered units that can be adapted...
https://www.tlxtech.com
http://www.ccoils.com
http://www.guardian-electric.com/custom-applications.html
http://www.snmfg.com
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Meyer,
Thierry lives in Laos, but spends alot of time in France. You can look at his profile and see some photos and read up on what he wrote about the subject.
I am sure he will give his input when he sees your post.
Regards
Chris
Cape Town
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Michael, pragmatically you're right that there are probably some more effective, cheaper and practical options by adapting a modern off-the-shelf unit. But part of this is for the fun and challenge to see if I am able to repair the old one.
Chris, thanks for the pointer to Thierry's posts on this topic. Here is the link to that page:
https://www.sl113.org/forums/index.php?topic=25242.msg180704#msg180704
He also used a lathe to open the CSS, but he opened it from the other end (the end with the setscrews). Right now I'm thinking that TheEngineer's approach is less destructive, so I will likely follow that. Seeing the innards, I figure mine probably also just needs a cleaning inside. It does work; but it binds along the way.
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Hi,
Yes I rebuilt my CSS, but I coudn't open it.
It was glued (Probably Loctite thread inside) and I had to cut out the front (shaft side) to open.
Inside it was all rusted. I think because this solenoid is energized all the time and warms up. Then when you stop the engine, it brings condensention in.
So I used the lathe mandrin to hold the shaft and de-assembly/extract, cleaned inside and greased.
But I had to make a new part to put it back together, and replace the part I took/cut out to open, on my lathe.
I have some pix posted already, but for more, unfortunatly I just forgot my hard disk in France with all the pix!!!!
However if you need more, i can try to explain better?
Now I cannot find the PN, and where its available, of the 2 pressure switches installed on the gear box. Because when the CSS works well, it is allways energized. Even when the engine is not truning..... And the engine stalls when selecting the D or R, of course I need to adjust on a working system. Seems it's not available at Niemoeller!!
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Hi Thierry,
(post modified)
For me, the pictures in your thread are sufficient; I can see what you did and I don't need any more.
Regarding your problem: are you sure the switches on the transmission are at fault? As far as I know, the CSS should be at 12 V when the ignition is on and CSS connected (I think both wires should show 12V relative to ground). But when D or R is engaged, one of the wires gets grounded and that energizes the CSS. There is a small wiring diagram in the BBB that shows this, shown in this thread:
https://www.sl113.org/forums/index.php?topic=23678.msg169338#msg169338
I'm saying all this because it's possible that in your reassembly of the CSS, you accidentally grounded something and that would then cause your CSS to be always energized.
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Hi Meyer,
You are correct, I have to check better these wires.
I may do that this week end...
And on the link you just sent there is the wiring wich will help me: Automatic trans electrical wiring diagram #1.jpg
Never saw this one!
Because its not fun to crowl under the car to do this one!!!
Thanks, I'll keep you informed.
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Hi Meyer,
This weekend I tested the ground wire, but everything went correct! So I connected again the system to the fuse, and it works!
I wonder if I don't have a intermittent ground or if due to the cold weather and the parked fperiod the pressure switches didn't wake up?
However for the the time beeing I cannot trouble shoot again until the problem occurs again.
I like this anyway, its a fast repair and cheap too.....
Thanks to you for kicking me to try to fix it again.
Best
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Sounds like good news, at least for now. Let's hope it stays fixed.
Having spent a lot of time on British cars, this is often how a lot of repair happens---don't rush to fix it; often the problem goes away on its own. Especially on the electricals. It's probably what's turned me into a procrastinator.
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New one now available
A000 072 0500
naj
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Interesting Naj,
Brentford still say NLA
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I checked. It is available, my dealer says they can order through Clasic Center. About EUR 900 without VAT.
But the Webparts says it is not available. But it is.
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Sounds like good news, at least for now. Let's hope it stays fixed.
Having spent a lot of time on British cars, this is often how a lot of repair happens---don't rush to fix it; often the problem goes away on its own. Especially on the electricals. It's probably what's turned me into a procrastinator.
Hence the old saying "Never put off until tomorrow what you can do
the day after tomorrow"
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Hence the old saying "Never put off until tomorrow what you can do
the day after tomorrow"
Ha, I have one just as good.
'' There's never time to do something right but there's always time to do it over again. ''
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:D
Good one Dan!
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Interesting Naj,
Brentford still say NLA
Its a new release.
naj
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Your solenoid is almost certainly internally rusty. I think I have a fix. I yellow zinc plated mine and although I soaked it in oil it ended up stuck. Horribly stuck. After looking at the various options for dissasembly I didn’t like any of them. After staring at it for awhile I figured out a solution. The center of the back side is brass. I drilled a small hole of around 5mm just through the center of the back. I then sprayed some oil in the hole and began hammering the shaft back and forth. After I finally got it to move I started spinning and spraying until I had flushed all the rust from inside the solenoid. Once I had it cleaned and lubed the way I wanted I tapped it to 6mm with a grease covered tap to avoid dropping any shavings into the solenoid. Here is the tricky part. I put a little cyanoacrylate (crazy glue) on a 6mm brass bolt and threaded it in just deep enough to match the thickness of the back cover and no deeper or you will restrict shaft movement. After the glue dried I cut it off and ground it flat with my dremel tool. Almost undetectable repair. Since your seems to be only maginally stuck you might only need a hole large enough to slip a plastic “straw” that attaches to your favorite spray can lubricant. 2-3mm.
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Ho Meyer sorry I didn't read for a long time this forum.
Yes I opened my CSS a while ago. I had to cut the side on my lathe, where the shaft comes out. It is glued and couldn't open. I cut the minimum to open, and made a little ring similar to what I cut out, to re-assemble and glue again.
I used the lathe also to pull strait the piston out of the solenoid.
The problem is that as it is always energized, it warms up and humidity condensate and stays in. This brings corrosion, and get all stuck.
attached are some pictures.
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Hi Chris,
The CSS is still working as of today. But now I have a problem with the injection pump!!
Wouldn't start anymore after she has been left a while parked...!
I just raised a topic.
Best
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Salut Thierry,
Nouveau sur le forum je m'attache à remettre en état un 280 SL de 69
Merci pour ta publication sur le CSS, très instructive
Quel est le débattement (en longeur) de la tige du CSS lorsqu'elle est actionnée pour appuyer sur la tringlerie et ainsi augmenter le régime moteur ?
Une idée de la force exercée ?
Je trouve mon CSS un peu "faiblard" même si la tige semble se déplacer librement (sans trop de corrosion donc)
Le débattement de la tige que je mesure aujourd'hui est de l'ordre de 15/18 mm et je ne suis pas sur que ce soit suffisant.
Bonne soirée
Marc (région lyonnaise, bien loin du Laos...)
Hi Thierry,
New on the forum I am trying to refurbish a 280 SL of 69
Thank you for your publication on CSS, very informative
What is the travel (in length) of the CSS rod when it is pressed to press the linkage and thus increase the engine speed?
An idea of the force exerted?
I find my CSS a bit "weak" even if the stem seems to move freely (without too much corrosion)
The deflection of the rod that I measure today is of the order of 15/18 mm and I'm not sure it's enough.
Good night
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Nice idea!
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I was having trouble with the CSS on my 69 280SL without AC. The thing would energize and stick in the extended position after the 12 volt signal was withdrawn causing a fast idle due to the linkage being pushed forward. . All connections were correct with senders from the tranny appropriate. I took it to the bench thinking it was dirty and lubed it. It spun freely and would not stick when pulling it to extension. I energized it with a 12 volt power supply and it once again stuck with 12 volts withdrawn. It was stuck so firmly that the throttle linkage springs could not defeat the extension.
From reading the forum I figured it was magnetized due to metals being exposed long term (sort of a memory) to the electromagnet. I then placed a clamp around the device preventing full travel of the piston by 1mm or so preventing mating of the piston surface against the inner housing surface. This resulted in no sticking and smooth piston retreat when the power was removed. This seemed to confirm the theory.
The housing seems very unforgiving to break open and repair. I decided to tap a half inch 4-40 stainless screw next to the piston rod allowing for the head of the screw to fit in the recess between the shaft and the rubber boot ring (a 3mm machine screw head was too large). I adjusted this screw in the car to not allow the piston to mate to the underside of the housing setting the maximum extended piston travel to within 1mm or so. This seemed to eliminate any effect of magnetism on the retreat of the piston. The result was a once again functional CSS. It does have about 1mm less travel which is workable. The hole allowed for extra lubrication. I was cautious drilling the hole to minimize any metal shavings from entering the housing. Placing a new rubber boot will require a bit of thought. I'm not sure how long this work around will function correctly, but I'm glad to not drop 1K on a new one just yet.
I have a photo and will try to post it. Happy to email it if it fails to load
Jim