1995 E320 Cabriolet hydraulic top operation problem
 

I just had all eight of the hydraulic cylinders from my convertible mechanism removed, rebuilt, and reinstalled because of multiple leaks. Now when I go to operate the top, it keeps hanging up or stop moving. I was extremely careful to label and reinstall the hydraulic lines in the proper positions. The hydraulic reservoir is full and topped off with fluid as needed.

What's the magic that needs to be done to get the top to work properly after repair? What needs to be reset? I remember having a similar problem that last time I worked on the hydraulics. It seemed to work itself out after a while. I've tried everything I can think of... manually setting the top in the full up and full down position, then starting operation... disconnecting the battery in hopes of resetting the mechanism.... all to no avail.

I'm trying to read the fault codes to figure out this problem. These are the instructions:

"Power Soft top test connection (4 pole) at Socket 2. The connection is located at the right front passenger footwell. To avoid the need for an extension cable, connect the black lead of code scanner to any good ground and red lead to a battery + source inside vehicle."

Where at the right passenger footwell is this connection located? My information tells me the X11/4 diagnostic (16-pole) connector is not used to access these codes.

I have a diagram but reducing it to attachment size pretty much ruins it. I sent you a private message.

Dean, thanks for the attachment. I found the socket, read the codes, erased them, then put the top through its paces until it faulted. I get:

Code 10 - Soft top fabric bow "raised" limit switch

What my top does... is from the top-up position, it unlatches and raises the compartment cover, raises the rear glass, then faults.

I took the three-in-one limit switch unit out from the driver's side rear quarter and tested them. All switches work fine. There's no adjustment, and I can feel the switch click when I raise the rear glass manually to the up position.

Am I checking the proper switch?

Fixed. I feel like a dolt. Careful as I was, I forgot to reconnect one of the electric leads to a microswitch that was hidden in the trim.

Thanks for the map. The codes from the diagnostic connector led me to the microswitch. The combination of your map, the 80 page booklet of diagnostic codes I downloaded from a member here, and the W124 CD service manual, helped me find the problem. It just goes to show that you can't have enough information for one of these cars.

The top now works perfectly.

Hey Convertible Guys, I have an issue with my top also. The portion of the top with the rear window doesn't properly lower. It just drops like a cable is broken or detatched. I haven't tried to remove or pull back the canvas to see what's going on. Do you have any diagnostic advice?

Much appreciated, as always!

Let me run this by you guys again....

I thought I sent you a PM on this. Did you get it? I believe I mentioned checking the hydraulic fluid level in the reservoir.

Kestas, I didn't get a PM but you did post a response to a previous thread I started on the same issue. Above you mentioned replacing or removing your top and a microswitch. I thought you might have additional information after going through that drill. Thanks for your help.

I have checked the fluid in the reservoir and it's fine. I went ahead and changed it out with new MB fluid, since it was a relatively easy procedure, in hopes that was the problem. No such luck. Any more ideas would be appreciated. Thanks again.

If I remember, during use, the rear bow comes down rather quickly. Perhaps something came out of adjustment and the rear bow now "bottoms out" in the folding top case, causing a jolt.

I'm not sure what determines the speed at which the rear bow falls. I thought it was something regulated by the hydraulic cylinders. Perhaps one or both of the cylinders are leaking internally.

Any external leaks?

Follow-up and a new problem
 

I determined the problem with my falling top to be that the connector from the piston to the top had stripped out on one side. The connector, shaped like a keyhole, was not available as a separate part. The dealer needed $750 for the entire cylinder mechanism. I took the connector to a machine shop where they inserted a pin into the stripped threads and welded it in, then retapped it for me. I reassembled and it works good as new, at least until...

...today, when I noticed a puddle of what appeared to be hydraulic fluid on the garage floor in front of the passenger rear tire. I located the source as coming from the hydraulics, but not exactly sure of what seal where in the mechanism. I'm sure I can identify once I get in there, but can the seals be repaired by a weekend wrencher, or do I need special hydraulic parts and skills? How do you best access the cylinders? Removal of rear seat and side wall? Once removed, is it possible to repair the cylinder without special tools or parts? I don;t see any applicable parts on Fastlane.

Kestas, I know you are a DIYer. Did you rebuild all your cylinders yourself, or get some help? I see lots of W129 "front cylinder" repair posts, but I'm not finding anuy helpful information using the search function. Any suggestions from the group are appreciated!!

It sounds like you have a leaky cylinder. Don't go to the dealer for new cylinders. They're over $150 apiece. If you can get the cylinders out I can get you contact info for Dennis Ficken, who can rebuild them for $30 apiece plus shipping.

This is a difficult DIY job, but it can be done. You have to detrim the back seat and sides. There are two cylinders at each side of the convertible top. I took the entire top mechanism out of the car because I couldn't get a fastener to budge. You may be able to remove the cylinders without taking the top out of the car. Small hands help here.

Don't replace just the leaky cylinder. The others are not far behind. That, plus the labor, overlap compels you to replace all cylinders you can get your hands on. You don't want to do this job twice.

Besides the four cylinders that control the fabric top, there are an additional four cylinders that are relatively easy to get at. They control the tonneau cover operation and locking. Might as well get those in for rebuilding also.

Here are a couple threads for additional reading:

http://www.benzworld.org/forums/2027630-post11.html

http://www.benzworld.org/forums/r129-sl-class/1307426-r129-soft-top-hydraulic-system-ultimate-thread.html

Sound do-able. Thanks for the advice. I have had the back seats and side panels off before, so that's not a problem. I don't have small hands, but do have fair patience. I hope I don't have to pull the whole top off though. That sounds like a fair amount of down time. I don't have a second car, so this will have to get done pretty quickly.

In reading over the weekend I followed links to Dennis' email and have contacted him already. I was surprised he didn't have instructions on how to get to the cylinders. I'll try to document for this BB. I had read enough to see that the recommendation is to do them all at the same time, so I'm taking your and others advice on that as well.

Are all the eight cylinders in the same vicinity? I guess the tonneau cover must have some cylinders back near the hinge mechanism.

I love this car and I love the satisfaction of doing the work, but it's getting a little old having to do something new every week or two. Oh well, I guess it's better than a stick in the eye and a car payment.

Dennis is more familiar with the SL models, probably because they are much more plentiful than the E320 cabriolet. Also, they have 12 hydraulic cylinders for the top!!

Of the eight cylinders for the E320,
- Four are at the bottom of the top, hidden in the rear fenders (two on each side).
- Two are in the trunk, one at each side near the hinge behind the trim panels.
- Two are accessible from the open tonneau cover - one for the tonneau latch, one for the rear convertible bow latch.

Make sure to label all hydraulic connections so they don't get mixed up, otherwise you may have a nightmare on your hands. And careful not to lose the clips for the hydraulic connections. I'm guessing MB sells them only with the new cylinders.

Kestas, one (okay, two) more questions just for fun. Start to finish, if you could have worked straight through, how long did this job take? (You can exclude the time spent tracking down the unplugged switch if you want.) Then, how long was the total down time? Thanks for your direction. I'm looking forward to getting another project underway.

David

Oh boy, tough call. I'm a different kind of DIYer. This car was down for the winter, so I took my time and was very meticulous. I was never rushed and stopped anytime I felt tired or frustrated. This broke the job up into many chunks of time. I'd give this job 10-20 hours. Naturally, there will be a pause in the job to send the pistons out for rebuilding.

You may luck out and not have to take the top out of the car. I couldn't get one of the fasteners off, so the top came out. It was a clevis-type fastener at the top of one of the hydraulic pistons. Once the top was out, the fastener was easily pursuaded.

Hello everybody I hate to 'revive' a old dead thread but this thread most closely resembles the problem I am running into. I have a 95 e320 convertable whose top canvas was just changed out by a local upholstery shop, now the top is acting weird. It will move up and down ,given enough time, and the windows and roll bars are going up and down as they should. I guess my first question is should the roll bar switch on the dash flash when the top is all the way up and the front latches at windsheild latched? Could some one possibly point me towards the top diagnostic socket and a list of codes?

I feel that a micro switch or two is not sitting right, I know the upholstery guys didn't index and reattach the small painted flaps correctly because one broke off on them and the other keeps getting hit while working the top. I guess i'll be fixing those two things too.

Thanks for any help

Try this for the codes W124 soft top manual operation 1994 E320 Cabriolet - Page 6 - Mercedes-Benz Forum

If your switch blinks during operation it's telling you there is a code. The microswitch on the drivers side rear in the storage compartment may need adjusting.

O lol its funny that you sent me that particular link I found it last night and was able to get some codes. There were several different codes I think I may have caused a couple in my messing around with the top when the car came back from the upholstery shop. I haven't been able to get the codes to clear. I tried two things one was to hold the switch on my tester until the top switch lit up keep holding until it goes out then cut off the ignition switch. the second was to just unplug the battery all night. The codes are still present. I was hoping to clear all these codes work the top untill in malfunctioned again and then get the codes and figure out where to go from there. Thanks for your time and help I greatly appreciate it.

Hello Kestas,

Hope you are still around on this forum!
If anyone else has any idea what that “electric lead to microswitch hidden under the trim” is all about, please let me know!

I upgraded all my cylinders, reassembled back and am stopping at this same place. The rear bow raises but the tonneau cover doesnt close when doing a raising of the soft top and get stuck in that position.

When I do a top down operation, though, the bow goes inside the compartment, and the tonneau cover closes properly. Has to be some switch or connection that I cant find and its driving me nuts!!! Im an inch away from taking a sledgehammer to the whole car :/

Please help!

I can't remember which microswitch it was. Did you check the codes for faults?

No, I dont know how and i think thats because i dont have the equipment.
Thanks for the reply though. My issue was exactly as you described so i was hoping you’d still be around :).

I'm working from memory, but it may have been the switch that is hidden behind one of the interior panels near the back set.

If you search my posts, you may find information on how to read codes for the top using a homemade code reader. The electrical ports to plug in the code reader is in the passenger side footwell.

The code reader itself is easy to build using a momentary switch and LED light. I used an old 35mm film canister to hold everything together. The plans to build it and how to use it are also somewhere in these threads. This is the same code reader used for reading codes from the engine.

Thank you, Kestas. Yeah, that homemade stuff isn’t me. Not nearly enough technical know how for it. If i knew what reader I have to buy and how to clear codes, I’d be on it instantly.

This has got to be a code or switch issue because the tonneau cover closes in the top down operation just fine, and gets stuck in the top up operation when the bow is raised waiting for tonneau to close.