When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello everyone. I think that this topic will have been discussed in the forum but forgive me because I can not find information. I want to replace the hydraulic fluid on the roof, can you tell me where I can fill the tank and what type of oil does the hydraulic system have? Thank you
2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
The dealer uses a screw in syringe. The two bolts on top are a filler and a decompression vent. I went for the solution of melting a neat hole in the top of the tank, with a soldering iron. Drilling can cause debris, posing risk of clogging, or worse. Afterwards, a screw and rubber grommet can act as cap. Reliable tape seems okay too, I would then cover up the glue where is sits over the hole.
OEM fluid is ‘Hydraulic Fluid ZH-M’. There’s been some discussion about cheaper alternatives on this forum, but it’s not worth the scavenge, imho.
I bought a few large syringes (without needles) at the local pharmacy, sucked the reservoir dead empty and refilled with new oil (an oil exchange and sucking out eventual deposits were my purpose). I used small hoses on the syringes to penetrate the reservoir, keeping sucking and filling stuff strictly separate. You’d have to re-do a few times for most of the oil in the whole system to be exchanged. After topping up you may have to run a few cycles (roof and roll bar) for air bubbles to escape to the reservoir (sluggish operation). Check level again after that, of course.
I noticed that sucking the oil out of the bottle into the syringe causes air bubbles to form in the oil. Cavitation I guess, not nice. Reason for me not touch the roof switch for a day, to let things settle.
Last edited by Frederick NL; Sep 11, 2019 at 10:28 AM.
I would not discourage any member from changing the oil, but personally, I see no material benefit.
In my 18 years of experience owning SLs with hydraulically-operated roofs, practically the only source of failure I've seen is leaking piston seals. These seem to develop after 15-20 years or so, and it's my guess that changing oil will not affect the service life of these seals.
I only want to replenish the liquid because it is at a minimum although my roof works well and I have checked the entire hydraulic circuit and there are no leaks. I would like to know if you advise me to drill the tank to fill it or fill it as they do in the Mercedes workshop? I read that the tank is filled by one of the screws but I don't know if the other screw must also be removed for the air to escape.
2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
As said STRICTLY NO DRILLING.
Bobterry: I see what you mean. At least my old oil was a lot darker than the new stuff, suggesting pollution (such a shavings) travelling through the system. The consensus on a German forum is that no oil has an unlimited life time. The years are passing on and on..
The consensus on a German forum is that no oil has an unlimited life time.
There are anti-corrosive additive packages which degrade over time, presumably, and again presumably, moisture content increases in the oil. But to what consequence?
I have four 28-year-old SLs. As far as I know everything in the roof hydraulic system except for the piston seals is original, and that includes the oil. I have disassembled dozens of hydraulic cylinders to replace faulty piston seals, and the internals appear like-new.
I simply have too much personal experience with roof hydraulics to change my point of view with regard to changing oil. But again, I would not discourage a member from changing their oil, since I realize this can provide peace of mind at a small cost.
2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
Bonkers, trivial pursuit, genius. Or none.
do you throw back in the used oil after a cylinder repair? Your reasoning is probably right, but how safely can you assume that those needs for repair had no relation whatsoever with the age of the hydraulic oil in question? (Disclaimer: this is mainly a protein computer reasoning exercise. As an hypothesis one could entertain the contradictory thought that new oil would instantly start leveling its content of microscopic seal particles by eating those away, whereas old oil then might have reached its saturation point and is at peace ).
2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
Yes, as stated in my #2 post, one bolt is for decompression (vent). Trying to fill through the port will be difficult as they are tiny. Someone said he used a thin wire, and conducted drops of oil along it. vul=fill ontlucht=air vent
...I just want to know if you have to remove a plug to let the air out while filling the hydraulic tank
My experience has varied, and you may find it very helpful to burn a small hole in the pump's plastic reservoir both to fill fluid and to let air out.
Originally Posted by Frederick NL
...but how safely can you assume that those needs for repair had no relation whatsoever with the age of the hydraulic oil in question?
The answer is not known, but the consequences of making a wrong assumption either way are not significant on a 16-year-old car.
There is this from Top Hydraulics website: "The shelf lifetime of the Polyurethane seals most frequently used is about ten years. Heat, water, and additives can even accelerate that decay!" (Emphasis added.)
The level of the hydraulic fluid is measured with the trunk open in the opposite direction: you give it to open the roof and stop the operation when the trunk finishes opening but before the roof begins to open, and you look at the level that must be between the max and min. Is this correct? I found it on a German page.
2005 R 230 SL350 (M112 3.7). Sold the 1966 W113 230SL recently
WIS instructs to close the roof, open the boot (normal way) and fill up to between the triangles. I guess that also means, although it doesn’t say so, rollbar down. I filled up to the top triangle, because it makes checking the level easier / more precise.
Does anyone know what the correct fill level is for the newer version pump reservoir? Screenshot from WIS for the revised pump... is it to the top of the “+”?
I'd regard the specification as being in the range defined by the length of the vertical segment of the "+". I also think the reservoir can be over- or under-filled to a considerable degree without consequence.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
do you throw back in the used oil after a cylinder repair? 
).
