Four quick questions about RST hydraulic fluid leak - Mercedes-Benz Forum
 
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post #1 of 4 (permalink) Old 06-15-2019, 12:24 PM Thread Starter
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Four quick questions about RST hydraulic fluid leak

R129 | 1999 SL500. Leaking hydraulic fluid just in front of rear driver's side wheel.. quite a bit, I would say approximately an eight-inch puddle every time the system is operated, which is infrequently.

Purchased the vehicle in February, and tested the RST operation prior — it paused half-way, and I knew this was due to the windows being out of sync. Noticed the leak in April, when removing the hard-top for perhaps the fourth or fifth time since purchase… I had never actually operated the soft-top until last week end, as I would typically take it off for a convertible Sunday drive and then put it back on again when returning home. But I decided to sync the windows and try closing it for the first time, and was surprised when it worked perfectly. However, there was a major leak, more than when simply removing and replacing the hard-top, from the previously-described location.

I put it down again and went for a drive with my girlfriend; it began raining (of course ) on the way back. We pulled over, and I attempted to close the soft-top via the red switch. It operated slower than before, and basically stopped half-way thru — but in a different position than when the windows were simply out of sync. The pump was whining. I pulled out the manual and locked the front manually, then had my girlfriend press the red switch forward while I pushed down on the back of the soft-top to lock it in the rear. We carried the hard-top upstairs and inside when we arrived home, and I've been driving it with the soft-top closed for the past week. The red switch isn't flashing (I've never seen it flashing) so everything seems to be locked / synced for now.

My understanding is that the front cylinders, above the windshield, are typically the first to go. These currently seem fine. The leak is only in front of the rear driver's side wheel. After reading thru the forums (and being tempted to try using Stop Leak) I've decided to instead do this properly and send out at least the one cylinder to be repaired.

1.) I know that once a single cylinder has failed and is subsequently replaced, the next weakest cylinder tends to fail soon after. So the advice is to repair / replace all of the cylinders at once. I purchased my SL with the intention of leaving the hard-top on 90% of the time anyhow, so the convertible really is something of a bonus feature. Because I use the RST system so infrequently, could I get away with perhaps just replacing the leaking cylinder in tandem with its not-yet-leaking counterpart on the opposite side, and expect more “life” out of the existing cylinders than if I replaced it on its own? Or is that not necessarily the next likely cylinder to fail?

2.) Should I expect the front cylinders above the windshield to fail next? I really, really don't want this to happen, and ruin the leather or her dress or something. It looks like these are fairly accessible; should I just go ahead and repair them now as well? The obvious answer is ‘yes’ but just in terms of time and cost there are other projects on the car I also wish to attend to (door speakers, hood pad, trunk and centre console pneumatic hinges, upgrade to Michelins; maybe preventative motor mount or suspension work, etc.)

3.) I've ordered two litres of Febi-Bilstein 02615 to refill the hydraulic system and reattach the hard-top until I send the cylinder(s) out for repair. Do I need to refill the entire system (1.25 litre) to re-attach the hard-top, or can I simply fill the (.25 litre) reservoir?

4.) There was a slight (1/4") offset between the anodized lower window trim on the door and the side window of the hard-top when it was previously attached, on the same side as the leaking cylinder… I had assumed from reading on the forums that it was actually more likely to be the door, not the hard-top, that was misaligned… but would a leaking / weakened cylinder lead to the hard-top not aligning fully flush on that same side?

Thanks in advance for any help; this is our third M-B and these forums have been amazing.
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post #2 of 4 (permalink) Old 06-15-2019, 03:02 PM
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You can latch/unlatch the hardtop manually. even when you hydraulic system is not operational.
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post #3 of 4 (permalink) Old 06-15-2019, 03:24 PM
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I've found that the proper fluid doesn't really affect the leather (once), but I can't say the same about clothing.

Only your car will determine which cylinder fails next.

You can operate/latch the hard top and soft top manually, even the tonneau cover.

If the door fits flush to the fender and quarter panel then it's the hard top. Read up on latching the rear of the hard top manually and make sure yours is latched.
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post #4 of 4 (permalink) Old 06-15-2019, 05:00 PM Thread Starter
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Quote:
Originally Posted by mahunt View Post
I've found that the proper fluid doesn't really affect the leather (once), but I can't say the same about clothing.
Good to know; it's mostly the leather I'm worried about ;-)

Quote:
Originally Posted by mahunt View Post
You can operate/latch the hard top and soft top manually, even the tonneau cover.
Would anyone happen to know if the only manual process for locking the hard-top the one described in this Top Hydraulics thread?

https://www.benzworld.org/forums/r12...ml#post4887196

It seems pretty involved (removing the inside of the back of the trunk, etc.) — should I just wait until I get new fluid, or will that not be as secure as doing it manually since the cylinder is broken?

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Originally Posted by mahunt View Post
If the door fits flush to the fender and quarter panel then it's the hard top. Read up on latching the rear of the hard top manually and make sure yours is latched.
Door fits flush to fender, so it must be the hard-top. I'll read up some more on this, thank you! It's always seemed “off” but because the red light has never flashed I'd assumed everything was proper. Thanks again.
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