E_S

Opening and closing the roof on a '99 SL500 to day, we discovered oil was leaking out on the ground through what seems to be some sort of drain in the side skirt on the left side of the car, just behind the rear of the door opening.

Roof (still) works fine. Guess one of the cylinders are leaking - any tips before I start taking things apart to find the location? No idea which cylinder(s) are located in this area..

thealien

It is either the tonneau lift or the bow latch. They are visible from the top stow away compartment when the tonneau lid is open. It's also much easier to see with the top up. While the top is up press the button to open. Once the bow unlocks and the tonneau lift release the button. You can now see the back of the storage area and the top of the 4 cylinders (2 each side). They are accessed through the trunk. Not a very difficult repair. Check you tube and there are some videos. I recommend repairing all 4 at the same time. It's not if but when the others will leak. Do NOT use O-Rings only proper cup seals.

Flush the system while you are at it!

E_S

Thank you so much! I guess it would make sense to refurbish all the cylinders.

Is it a reasonable job to replace the seals myself (experienced DIY), or should I send the cylinders in for remanufacuring?

One question: The system does not have any bleeding. How do you ensure air is out after replacing cylinders?

thealien

Without knowing the cars history I/we can't be sure if any have ever been replaced or repaired. With that being said I did mine in batches. All 4 in the trunk (the ones you are having issues with) you have to remove much of the trunk interior (easy). The 2 windshield cylinders (and maybe the junction block). I have done 1 main lift and 1 bow cylinder. I have a way to do main lift and bow cylinders without taking the car apart.

I would take the pump out from under the spare, remove the tank and wipe out the sediment, mine was nasty. Reinstall the tank (put a drop of blue loctite on the clamp screw threads) reinstall, add new Mercedes Benz fluid and flush the whole system. I would do this soon as you can.

Rebuilding those 4 cylinders (and the windshield cylinders) are easy to rebuild. Cup seals are about $25+ per cylinder. Or you could send them to Top Hydraulics for rebuilds. He is pretty fast, well respected and replaces the seal on the bottom of the piston as well as the seals for the lines for about $65 a cylinder or $95 if you do an exchange and he sends you rebuilt cylinders and you send yours back. I used him for my bow cylinders (harder to rebuild) and did the exchange so I could replace as soon as removed while everything is fresh in your mind.

There is a member On another forum named Swany that has a fantastic tutorial also showing how to do main lift and bow cylinders without removing the interior. He also shows how to rebuild the cylinders!

E_S

Thank you again!

Checked out the Top Hydraulics site. They offer rebuild of a complete set including the distributor for $630. As far as I know, the cylinders have never been replaced - as the original owner from 1999 to 2016 mostly used the car with hardtop on. (yeah, I wondered the same, but he found the FL sun too hot..)

I suppose it would make sense to take all of them out and send the complete set in for a rebuild, then it would hopefully work for a long time again. The oil flush will of course be done in the same process.

What about air in the system and bleeding after replacing the cylinders? WIS only mentions to be as quick as possible disconnecting and reconnecting lines, sounds like a somewhat wonky way..

thealien

Personally I am against doing them all at the same time unless you plan on doing the exchange program which is about 50% more money.

There's a guy on another Forum that just replaced all his cylinders. and now he's having an issue that he's been having a hard time diagnosing for a couple of weeks. I am not saying this would happen to you but once you disturb 11 cylinders 22 lines a bunch of clips and then a problem arises where is it?

If you only do them in batches you can isolate problems in my humble opinion.

Again you did say you were mechanically inclined I would give a shot rebuilding at least those 4 by yourself?

And again personally I would do the flush now. That way any further operation of your hydraulic Roof System you're not circulating grit and dirt throughout the system!

The system will self Purge after a few cycles of the roof no worries about air in the system.

sneezix

I did all of my cylinders, but not the distribution block. Of course, then the block leaked, so I did it, too.

Like thealien said, the system self bleeds. I flushed mine by removing the return line from the pump, and putting it into a bottle. Then ran the top a few times, making sure that the pump reservoir didn't go dry.

Granite State

New owner here and I'm in the middle of this too. I've been seeing lots of cheap o-ring sets and was wondering about their viability. I've found the ones with the red cups for about $25 a set on mbseals.com which look like the better option. Going to rebuild them myself, look quite simple to do.

thealien

I also used the MBseals. When you disassemble you will see that cup seals were the original type seal. You have to ask yourself do you want to do this job again? If not I would use proper cup SEALS or send them to top hydraulics.

I have found all of them easy to repair and replace the seals except for the bow cylinders which I sent to top hydraulics.

On a different Forum there is a member named Swany who put together a fantastic removal and repair PDF. He even has a couple of tips so you don't have to remove the interior for the both cylinders, I used it and it worked for me.

rich8566

The hydraulic system is a self bleeding system.