Roadster Soft Top (RST) hydraulic system fluid renew for MY 90-98

[karas]

Originally Posted by lynns

Jim are you sure that your pump p/n 129800 0048 is not really p/n 129800 0548 ?

Note: this is not in any way meant to take this thread OFF TOPIC but FYI the RST electronic controller for a 1990-1993 is p/n 129820 0097 and has a seperate rollbar controller if built prior to 11/92. After 1993 the rollbar controller was incorporated into one controller unit.

Pretty sure...... unless those crafty Germans built mine during Octoberfest.

[lynns]

Originally Posted by karas

Pretty sure...... unless those crafty Germans built mine during Octoberfest.

Jim, that's a clear enough picture for me. If I enter p/n 129800 0048 in Parts.com it doesn't come back with availability. So this is where EPC comes in if you were to need a new pump.

Take a look at the p/n's for the older pumps at FOLDING TOP HYDRAULIC SYSTEM

Try reading the first attached PDF and see if it gives you some additional information.

[chriswufgator]

Originally Posted by lynns

Chris, I know you have been looking for a filter p/n for the 1998-2002 RST hydraulic cylinder system but as yet I have NOT been able to find one for the newer pump p/n 1298001948 like the OLDER pump that has a wire mesh filter built into the return line.

Sorry Charlie! I mean Chris.

Well now I'm really confused. So the consensus is, there is no filter is the newer ones?

[harley03joe]

Originally Posted by lynns

Renewing the hydraulic system fluid every 25K miles or every 2 years should extend the life of many of the hydraulic system components. This is not a part of Mercedes prescribed maintenance, so most cars are still running around with the original fluid (plus years of accumulated contaminants).

Here is a proactive approach, which I believe will improve the longevity of the hydraulic system.

1) With the soft top stored and roll bar lowered remove the R129 spare tire. Under the spare tire you will find a plastic cover over the hydraulic reservoir. Remove the plastic covers three nuts with a 10 mm socket wrench.

Note: The total capacity of the system is 1.25 liters, so you should have 2.0 liters of fresh hydraulic fluid (MB p/n 00098910310 or Febi-Bilstein p/n 02615 = p/n 0009899103 = p/n L7070-97881) in order to flush the entire system. My reservoir holds 250 ml when the fluid level is between the min. and max. mark. Here is the MSDS for Febi-Bilstein 02615

3) Remove the reservoir cap and approximately 250 ml. of old fluid with a rubber bulbed battery filler then add new fluid to the reservoir so that you have about 400 ml in the reservoir. Remove the reservoir return line (tube closest to you when bending over into the trunk) with a 12 mm wrench. Place the return line into a >500 ml container. Note: please read below if you have an older hydraulic pump like the one pictured above.

4) Now have someone in the car. Turn the ignition key to the number two position. Cycle the soft top and roll bar 4-5 times and refill the reservoir to approx. 400 ml as needed between cycles. Then fill the hydraulic pump to the min/max line. Note: you will eventually see the color change to the new fluid color.

5) Replace the reservoir return line, cap, and plastic cover. Wipe up any mineral oil spillage. Return the plastic cover. Replace the spare tire and put the trunk back together in the reverse order.

I did my first fluid flush/renew on my seven year old 30K mile SL. I tested the pH of the old and new fluid. Both read the same slightly acidic pH of 5.5. If you look at the attached pictures you will notice a color difference. The old fluid (left vial) looks like a beer color while the new Febi-Bilstein 02615 fluid (right vial) is clear.

QUESTION:
When You Do This >>>>> Remove the reservoir return line (tube closest to you when bending over into the trunk) with a 12 mm wrench. Place the return line into a >500 ml container.

Does FLUID Come Out Of The Port On The Motor That The Line Was Removed From ??

Thanks
Joe

[chriswufgator]

Originally Posted by harley03joe

QUESTION:
When You Do This >>>>> Remove the reservoir return line (tube closest to you when bending over into the trunk) with a 12 mm wrench. Place the return line into a >500 ml container.

Does FLUID Come Out Of The Port On The Motor That The Line Was Removed From ??

Thanks
Joe

Nah, it'll come out of the line you just unhooked. That line carries the fluid that's supposed to be flowing back into the reservoir.

[harley03joe]

Originally Posted by chriswufgator

Nah, it'll come out of the line you just unhooked. That line carries the fluid that's supposed to be flowing back into the reservoir.

Ok Thank You
Joe

[Gwillie]

Originally Posted by lynns

The above quote from Jim Karas after he had R&R'ed all 12 cylinders with no problems yet his hydraulic fluid renew did not work as easily as my 2000.

There has been a lot of discussion around the subject of HOW to bleed the earlier pump with the two pressure lines. After listening to the various inputs, I would suggest that the proper way is to put the reservoir cap with the filter into the waste jar and in turn actuate the top and roll bar switches in the following manner. First, make sure you have fluid in the reservoir. Actuate the raise and and lower alternately until you have clean fluid running into the jar. Repeat for the roll bar. There is no need to remove either of the high pressure outlets to the pump.

By the way, the suction side of the pump draws fluid directly out of the reservoir. In the later -67 pump, the filter is inside the reservoir and protects the pump by filtering fluid before it enters the pump. The screen type filters should never need replacing and indeed there is no entry on the parts break down shown for them. To reach the later model filter, you must remove the reservoir but understand that you should be prepared to replace two o rings. the one between the pump and the plastic reservoir housing and the one on the end of the filter. Best to leave this alone unless you have a leak in the trunk that might be coming through the reservoir o ring.

Jim Karas, I think the reason you got air in the system was because of the disconnected high pressure lines or the reservoir ran dry. That should not happen the next time you change the fluid. Don't be afraid of trying it again assuming you have more fresh fluid.

Finally, the issue of why two pressure lines on the older model? I suspect after looking at the service diagrams, that it is just a more costlier method of distribution that was corrected in later models. Never use two high pressure hozes when one works just fine.

Everyone should please remember that this is a 2800 psi system and wear safety glasses. Not every leak will be benign. Other convertibles use bigger cylinders and lower pressures and are more forgiving of seals and tolerances.



Regards,

George Anderson

[chriswufgator]

Originally Posted by Gwillie

In the later -67 pump, the filter is inside the reservoir and protects the pump by filtering fluid before it enters the pump. The screen type filters should never need replacing and indeed there is no entry on the parts break down shown for them. To reach the later model filter, you must remove the reservoir but understand that you should be prepared to replace two o rings. the one between the pump and the plastic reservoir housing and the one on the end of the filter.

Ok, so there IS a filter after all...

But it doesn't need replacing, you can just wash it out? It's a metal screen filter?

[karas]

Originally Posted by Gwillie

There has been a lot of discussion around the subject of HOW to bleed the earlier pump with the two pressure lines. After listening to the various inputs, I would suggest that the proper way is to put the reservoir cap with the filter into the waste jar and in turn actuate the top and roll bar switches in the following manner. First, make sure you have fluid in the reservoir. Actuate the raise and and lower alternately until you have clean fluid running into the jar. Repeat for the roll bar. There is no need to remove either of the high pressure outlets to the pump.

By the way, the suction side of the pump draws fluid directly out of the reservoir. In the later -67 pump, the filter is inside the reservoir and protects the pump by filtering fluid before it enters the pump. The screen type filters should never need replacing and indeed there is no entry on the parts break down shown for them. To reach the later model filter, you must remove the reservoir but understand that you should be prepared to replace two o rings. the one between the pump and the plastic reservoir housing and the one on the end of the filter. Best to leave this alone unless you have a leak in the trunk that might be coming through the reservoir o ring.

Jim Karas, I think the reason you got air in the system was because of the disconnected high pressure lines or the reservoir ran dry. That should not happen the next time you change the fluid. Don't be afraid of trying it again assuming you have more fresh fluid.

Finally, the issue of why two pressure lines on the older model? I suspect after looking at the service diagrams, that it is just a more costlier method of distribution that was corrected in later models. Never use two high pressure hozes when one works just fine.

Everyone should please remember that this is a 2800 psi system and wear safety glasses. Not every leak will be benign. Other convertibles use bigger cylinders and lower pressures and are more forgiving of seals and tolerances.



Regards,

George Anderson

Thanks. But when I did it the reservoir did not run dry nor did significant air enter the system until I tried exactly what you just recommended. Upon closer inspection it appears that a return line can be disconnected from the large knob proximal to the filter. I'll try putting this line into the waste container when I get a chance and see what happens.
jsk

[lynns]

Originally Posted by chriswufgator

Ok, so there IS a filter after all...

No, No, No.... filter on your 2001 R129.

This thread is for 1990-1998 R129's.