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1991 500SL AMG
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12 Posts
Discussion Starter #1
I have a 1991 500SL and I just had the power window motor and gears replaced on the passenger door. Now when I go to put the soft top down, my windows go down, the rear window folds up and the back opens up but the soft top doesn't move. Is there a sensor that determines if the windows are down that might be causing the problem?
 

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1997 Mercedes C230
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113 Posts
SOUNDS TO ME LIKE YOU HAVE A BAD ACTUATOR OR SOFT TOP PISTON OR 2. HAVE YOU NOTICED ANY FLUID LEAKS FROM THE VEHICLE? A LOT OF TIMES WHEN THE I HAVE A CUSTOMERS 94 500SL IN THE SHOP RIGHT NOW WITH THE EXACT SAME PROBLEM AND WERE GOING TO HAVE TO REPLACE A FEW OF THE PISTONS THAT MOVE THE TOP. THEY TEND TO GO BAD ALL THE TIME
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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661 Posts
window sensors

A few comments:

Canesso, you are right about a possible correlation to the work done on the door window system. The models '90-'94 have micro switches that tell the soft top controller when the window is down. If the windows are not signaling that they are down, then the controller will not move the top up, so that it will not slam onto the door windows. Whoever did the work on your window regulator and motor did not necessarily break the switches or wiring; they often corrode or develop grounding problems.

epictofer, we look forward to rebuilding your cylinders to better-than-new condition, or to sending you a set up-front with follow-on core credit... :)

edcarls, synchronizing the windows would be right on in '95+ model years. '95+ models have magnetic sensors in the doors that tell the controller when the window has reached or passed them. The upside is, these switches don't corrode as easily. The downside is, the controller has to rely on its memory to determine where the windows are. '90-'94 model years do not need the controller reset to re-establish the window position in the controller's memory.

Hope this helps,

-Klaus

[email protected]
 

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1991 500SL AMG
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12 Posts
Discussion Starter #5
Where are the micro switches located

Does anyone know where the micro-switches are located the determine if the windows are down?
 

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1991 500SL AMG
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12 Posts
Discussion Starter #7
Thanks for the replies.

It turned out to be the micro switch. I got to enjoy the top down yesterday.

Thanks everyone.
 

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300SL
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7 Posts
Klaus Witte, Top Hydraulics is a great guy very caring. I highly reccomend him.
I also am experencing closing trouble. Installed a new top pump motor and a rebuilt cylinder from Klaus. Both parts are working fine, opening is not an issue however when closing the windshield must be latched with the tool. The tonnau cover remains in the up position. This can be lowered by hand and the rear of the top can be lowered into place. Then I can lock the back down using the top switch, light goes out top is securely in place.
Any sugestions on what else I need to replace on my 300SL.
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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661 Posts
troubleshooting

Trew,

thank you for your kind words. Let's take this step by step. Could the front locks simply require lubrication? If there is enough pressure in the system to lock the rear and the tonneau cover, then the front locking problem is often contained to lack of lubrication or alignment. A bad leak in a front lock cylinder could also prevent it from completing the locking cycle. Has that been checked on yet?

Once the front locks close all the way, hopefully the other problems will go away by themselves, or we can tackle them piece by piece...

-Klaus

[email protected]
 

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300SL
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7 Posts
Klaus, haven't checked for leaks yet, will when the rain stops. As I explained the tonnaue cover came down and rear section of the top latched properly after I locked the windshield latches by use of the wrench. The top pump motor was replaced however the dealer did not purge the oil from the system, very dirty. I will have it purged and we'll see how that works out. Is there a post to explain the front latch system?
Marlin
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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661 Posts
front lock, fluid, and dealer

Marlin,

I would like to respond to three issues here:

1) You can check the front lock cylinders for leaks yourself, and removing them and sending them in for rebuild is quite simple. In case there is a leak, you can just send us the cylinders mounted inside the locks. Here is a detailed DIY for inspection and removal of the front lock cylinders: http://tophydraulicsinc.com/R129 Front Locking Cylinder Removal.pdf

2) Purging the old liquid is a good idea for any SL that hasn't had it done in several years. The fluid ages, accumulates small particles, and it may accumulate water in it. If your fluid has had any additives in it, it is very important to flush very thoroughly. Additives or most other oils make the seals swell, which is ultimately bad for your system. Purging the liquid has been covered in the stickies. In a nutshell, you want to stick the hydraulic return line into a waste liquid container, empty the reservoir by operating the top manually or automatically, fill up the reservoir with the correct fluid (MB dealer fluid or FeBi 02615), and keep operating the top while topping off
the reservoir until there is positively only clean liquid coming out the return line. Purging the front lines is a lengthy process because the lines going to the front hold about as much liquid as the cylinders themselves, so it takes many cycles of the front locks to really clean out those lines.

In your 300SL, the return line is screwed into the reservoir of the pump, under the spare tire. In later models with only two lines going to the pump, it is the one towards the rear.

3) Dealer involvement. I'm glad you are mentioning that. We are having more and more dealers buying upgraded cylinders from us, and that is both good news for the end users, as well as a tribute to the quality of cylinder upgrades. Originally, it was only dealer employees telling customers behind closed doors about this option. By now, possibly most dealers will actually let you provide the upgraded cylinders, or order them for you, if you show that you are educated about it and insist on this option! Our up-front shipments arrive in most parts of the country within two days, and they can live with that.

-Klaus

[email protected]
 

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300SL
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7 Posts
Klaus:
Followed your advise.
1) You can check the front lock cylinders for leaks
Check both for leaks and found none.
2.Purge system
Had the fluid replaced. I don't think they purged the system, closing is slow.
The top is opening properly no problems.
Closing issues are, still won't latch at windshield. Tonnaue cover is now closing after your tip on the white switch. Used the top wrench to push it down while holding the closing switch down.
Thanks for the help, you lowered my frustation level.
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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661 Posts
Additives to hydraulic fluid, Top Position Switch

Marlin,

thanks for the update. Here are the issues that come to mind now:

1) Top Position Switch. I'm glad the "Top Position Switch" in the left front of the storage compartment has been identified as part of the problem. Obviously, that situation can be fixed by finding out why the retracted top did not trigger the switch before. Is it working now? There is an adjustment screw on it... (see picture below - the picture was taken from a parts car, so there are a few things missing around this switch)

2) Slow movement. Is your top moving faster now, after a few cycles, and have you been able to compare it to other R129 roofs? You may just want to time the full cycle (after you manually unlocked the front for now :) ). Your pistons are more sticky than those in most R129s, but that shouldn't be much of an issue on the cycle time after the top has just been cycled once before (see next issue).

3) Front locks not unlocking. Outside of my next comment, there are still the possibilities of needing lubrication in the latches and needing some alignment of the prongs on the soft top. If you see that the latches are well lubed where they receive the prongs from the soft top, then that takes care of the lubrication. If they receive the soft top well upon closing and they latch right away, then that confirms good alignment.

Here are the two culprits that may play the major role in your latches not locking: sticky cylinders on account of additives in the hydraulic fluid, and possibly the pump not putting out enough pressure.

The tonneau lock cylinder that you sent us back as a core (after ordering an up-front shipment) has been exposed to an additive in the hydraulic fluid such as "No-Leak" or "Stop-Leak", or altogether to an unapproved hydraulic fluid with some kind of additives in it. I can tell from the specific discoloration and swelling of the plunger seal. These additives are softeners that are supposed to give old seals their elasticity back, and make them swell a little to improve sealing. The problem is, the plunger seals swell so much that it makes it very difficult for the plunger to move inside the piston! In particular, the swelling causes much higher stiction, which means much more force required to move the cylinders initially.

Here is what I found on your old cylinder: Just to break loose the piston itself, meaning overcoming the stiction, without any lock attached, required 70 pounds of force! That is several hundred times normal... This stiction is greatly decreased once the cylinder has been moved, but it will then slowly come back once the cylinder is sitting for a while.

With the active area on the front locking pistons and the pump putting out the specified 2800 psi, the available force on the front pistons for unlatching should be 400 pounds. The plunger diameter of the front cylinders is a little larger than that of the tonneau lock cylinder I just described, so there could be even more stiction on these cylinders. Add to that the force required to move the latch itself, and you would use up a major fraction of the power the pump can put out. However, it could just be that your pump is not putting out full pressure any more. (Top Hydraulics did not supply that pump).

4) Pump. You mentioned that your previous pump had burned out. Anyone still want to put additives in their system? The replacement pump may not be putting out the specified pressure - we'd be happy to test it free of charge if you send it in. Just pay us for shipping it back. Removal is easy (just disconnect the hydraulic lines, unplug the electrical connector, and unscrew the four 10-mm bolts to remove the pump from the trunk), and the pump ships for some $15 in a Large Priority Mail Flat Rate Box.

Hope this covers most of the issues now!

-Klaus

[email protected]
 

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mercedes 500sl r129 1990
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24 Posts
have a problem with my soft top problem being it wont budge neither of my move when i activate switch. Should they roll down on my 1990 500sl thanks
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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661 Posts
windows not moving?

burtie11,

if I understand you correctly, then either window is not moving down when you try to operate the top. Yes, the windows must come down before the top moves.

Have you checked the fuses in the trunk carefully?

-Klaus

[email protected]
 

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mercedes 500sl r129 1990
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24 Posts
Yes checked all fuses and all seem okay. I have read some about relays that can go bad in the module could that be my problem. Any suggestions are welcome. Thanks klaus.
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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661 Posts
reading codes

Just two more fuse questions. One, does the horn work? Two, do you have that metal strip below the lowest fuse in the trunk? It is a fuse, as well - see picture below. If both questions check out okay, your next step is to read codes to find out if it is the controller. It's not only relays going bad in the controllers, btw.

Try thread http://www.benzworld.org/forums/r129-sl-class/1230037-homemade-diagnostic-code-reader-my90-95-a.html, for example, or browse through the ultimate RST controller thread in the stickies for instructions on reading codes...

-Klaus

[email protected]
 

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2000 SL500 Mineral Green
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222 Posts
Klaus, what should I use to lubricate the latches and where should the lube be applied?
Thanks for all your excellent advice.
 

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'03 SL Kleemann, 1997 SL320 Pano Top, Tesla Model X
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661 Posts
lubrication on locks

Herb,

I am not too concerned exactly which lube gets used on the latches, as long as it gets done now and then. I'm sure someone can recommend some fancy grease or lube that sticks extra long and doesn't go all over the place. I personally use just what is readily available when I think my own cars could use it. Generally, the thicker (more viscous) the grease, the better it sticks and the longer it lasts. No need to apply a lot - just use common sense. You don't want the prongs on your hard top to be thickly coated with grease, in case you touch them while the hard top is stored.

The places where the lubrication wears out the fastest, are those where the locks receive the prongs from the soft top or hard top or tonneau cover. With the locks open, just apply grease onto the surfaces where there is sliding action. Use common sense on the rest of the locking mechanisms: if they are really clean and new looking, you may not have to bother lubing them at all. It is rare that we get bad ones in for repair. There is generally no need to remove the windshield header panel for the front locks - they are pretty well protected. Try to avoid the cylinder shafts if you are spraying stuff like WD-40 - I wouldn't want any additives in the lubricants to work their way down into the seals of the hydraulic cylinders... The hydraulic cylinders themselves don't have to be lubed, and they should be left alone.

Hope this makes sense,

-Klaus

[email protected]
 
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