George993

hi, I've rebuilt the cylinders and put them back in and now I'm puzzled with the switch on the left bow extension cylinder (cylinder part number 1298001772). The switch is shown in the photo. The problem is that the plastic flap on top of the microswitch is pressing (spring) on the microswitch, putting it into a CLOSED position. When I pull on that plastic flap, the switch goes into OPEN. And for the proper top operation the opposite seems to be true: normally the flap should not be pressing on the switch (switch OPEN), and when the top is folding, some other part should press on the flap/switch, putting it into a CLOSED position.

So I'm puzzled, how should it work? What went wrong and how to fix it? The top fails to operate due to the switch not being in expected position.


BTW, I've also discovered a very simple way to do the main lift cylinders part number 1298000272 (the big one below the bow extension). All the instructions talk about removing the bottom bolt, which is a pain to get to (lots of interior disassembly). Instead, I've just disconnected to top bolt, pushed the rod in not to scratch it, removed the retaining ring - not too difficult, as this is the ONLY cylinder which has a notch to push the ring out, and pulled out the rod for a rebuilt and all the seals change.

AndreasHannover

The part screwed at the top of the piston is not symmetric. Did you assembled it the way you disassembled?

George993

Andreas, yes you are right! Thanks! Meanwhile I've also removed the switch with its housing (luckily it can be removed without removing the piston) to see for anything wrong with the spring etc - nothing wrong.

So the way it seems to be working is that once the piston rod is fully in, the asymmetrical steel block which is screwed to the end of the rod is pushing on the plastic flap "from the bottom", opening the switch.

Important point of reinstalling the cylinder into the car is to orient the metal block at the end of the rod in a way, that a larger part of the block is on the same side as the switch. Thanks again.

Sandy Eggo

Have you watched this video?

Start around the 4 minute mark where he talks about damaging the frame around the microswitch (and provides a very brief explanation of how the microswitch works). To me, in your pic, the upper left portion of the frame (about 1/2 inch above pencil lead) in your pic looks smooshed.

mulladp

Just watched that one on the weekend and was going to refer to it as well but you beat me to it

mulladp

I have just did one of my top cylinders this weekend. Rebuilt the seals myself with a kit
When I put it back on and tested it the top started working but it looked like the it was still leaking fluid and quite a bit

• I may have scored around where the metal clip to hold the cylinder in getting it out

Will the stop not work if it is leaking a lot?
The windows will cycle but everything stops after that and the light is solid red on the top switch
Also, the roll bar does not go up or down now as well

This is for a 98 SL500
I have

• Cycled through the manual top up and down
• Did a roll bar reset
• Did a windows reset
• Checked fuses
• Checked health and charge of battery - all good
• There are no fault codes
• The micro switch on the cylinder was not damaged in removal and repair
• Hydraulic fluid is full

Any help would be appreciated

George993

Thanks Sandy Eggo , excellent video, I should have watched it before starting not after finishing :-). But luckily my switch/frame are not damaged. The problem was indeed that the block screwed at the end of the rod was inverted, so it was not pushing on the switch at all. The top works perfectly now (with all 12 cylinders rebuilt).

mulladp - top will work, or not work or will just work part way if there is a leak - depending on the leak size. Is the cylinder you have just rebuilt leaking or is the leak elsewhere? I have observed that you may only have one leaking cylinder, so you rebuild it. But once the leak is gone, the pressure increases in the system and blows the seal in another cylinder. So you rebuild the other. And after that another..... So check others for new leaks or just bite the bullet and do them all. And after you rebuild them all, make sure to also replace all the fluid and clean the pump container.

Another problems are the switches - best to have DAS or something similar to check the status of the switches (or volt/ohm meters as a minimum), as if they are damaged or not connected etc the top will not work properly.

Also a visual way to tell the pressure (leak) problems vs switch problems is to observe the movement - if it looks more like the top is struggling (or sometimes works or not depending on temperature or other factors, or completes the cycle once you push it a bit), it's probably a leak somewhere or a bad pump. If the top works vigorously but suddenly stops (and always stops at the some point) it's most likely a faulty switch. Good luck!

George993

Also obviously never buy and never use the o-ring based rebuild kits people are selling all over. Those are not meant to seal a moving rod in this type of applications. U-cap seals should be used, made of appropriate material for MB approved fluids and only MB approved fluids should be used.

And the u-cap seals are unidirectional, so if reverted, they will not seal properly and leak

mulladp

Thanks
I was going to change both top cylinders but I wanted to test the one that I did. None of the others are leaking and fluid is full. There is no movement on the top as well. The windows will cycle with the top up or down but once they are down - nothing- the top switch is flashing. top was functioning fine before the rebuild. I guess with nothing happening it is more than likely a switch stopping the process. Roll bar does not work either

George993

The best way to start the top operation after a cylinder rebuilt is to manually (using that special wrench) lock it in the down or up position (4 locks - two in front, two for tonneau cover, two for the back of the top).

This puts all the switches in the right state. Otherwise the control computer can get confused with various switches in wrong positions as the top is partially moved.

It may or may not fix the problem, but it should be done first if the top is not moving by itself. And with the weather getting colder in some places, make sure that the top is warm, otherwise the plastic back windows can break when trying to operate a cold top (ask me how I know)

mulladp

Thanks
Have done most of that except with my 98 it does not have the rear latching ability
Think that is odd as when I did an internet search it showed there should be 2 red coloured latches in back
Mine does not have
Manual states they are not there either
Not sure why they would do that

George993

The manual is a total BS. Older cars had two openings in the trunk carpeting to allow access to the latches using that special wrench (or a similar tool - a regular open ended spanner should work too). Those openings do not exist in the newer cars. Instead you need to pull the carpeting out on both sides near the trunk cover hinges to get access to the latches which you then operate manually.