Renewing the hydraulic system fluid every 2-3 years or 25K miles 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 000989910310 or Febi-Bilstein p/n 02615 = p/n 0009899103 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

rmeuropean Febi-Bilstein p/n 0009899103 @ $8.42/Liter

autohausAZ Febi-Bilstein p/n 0009899103 @ $9.49/Liter

Note: always check to total with shipping. Sometimes if you buy $50-$65 worth of product they knock off the shipping but you have to plan in advance to wait 7-10 days for the free ground shipping.


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 11 mm wrench. Place the return line into a >500 ml container.

4) Now have someone in the car. Turn the ignition key to the number two position. Lower the Soft Top. Cycle the roll bar first then the soft top 3-4 times refilling the RST 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 a flush/renew of my system fluid today on 7-13-07. My car is seven years old with 30K miles.

 

Renewing the hydraulic system fluid every 2-3 years or 25K miles 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)..

Lynn,

First, thanks for all the valuable info you and so many others post here. It's highly liberating.

I'm also sorry if re-visiting threads this old is poor etiquette, but I had a question or two about the this process, which I am planning to attempt this weekend (immediately following the cylinder rebuild; I have seals coming from KBelov).

My only fear about this move is the potential for any hydraulic sytem to be airlocked. When I discussed this repair with several (non-MB) mechanic friends, it was both of their immediate concern that there must be some kind of bleeding procedure. I'm thinking that your procedure would serve as a de facto bleeding -- did you note any air coming out of the return line before the fluid?

Also, when the return line is off and draining into the waste container, isn't there a danger that the pump is drawing in air through the opening?

I have seen it written that this system doesn't require bleeding, but I'm still concerned about it. Anyone have any assuaging thoughts?

Ich wünsche Ihnen und Ihre Familie alles gut….

Dan P.

 

2000 hydraulic system fluid flush and renew

Hey Buddy, Keep up the GREAT work!!! Have you ever had to change any of the cyl. on your car? I did the left front one last year and have had NO other problems!!! Hope my LUCK continue's. I checked my oil when I did the work and mine was still CLEAR so I will leave it for now. Maybe I'll put it on the list for next Winter!!!!!!!

 

Have you ever had to change any of the cyl. on your car?

UPDATE: Hi Paul, I haven't had to change out any hydraulic cylinders on my 12.5 yr. old triple black 2000 with 61K miles. Knock on wood....
FWIW, I've changed the hydraulic fluid two times (25K and 59K miles) since I bought the car in 2006.

 

Hey Buddy, Keep up the GREAT work!!! Have you ever had to change any of the cyl. on your car?

NO, I have not replaced any hydraulic cylinders. Fingers crossed....

 

i just bought fuiled from my mb dealer and it cost $23 for a quart and it was green in color. so what is the dif from clear to green??????

 

i just bought fuiled from my mb dealer and it cost $23 for a quart and it was green in color. so what is the dif from clear to green??????

Luigiz,
When I put the p/n Q1320001 from the blue can that you show in your DIY it comes up as 'M-B Power Steering Fluid' at www.autohausaz.com/search

You may want to check this out and possibly flush your hydraulic cylinder system fully with p/n 000989910310.

 

What type of hydraulic fluid should be used

Ouick ouestion guys,

What type of hydraulic fluid dhould be used to top off the resovoir for the soft top operation? Does It have to be Mercedes factory fluid or can I get something from the local auto parts store?

Thanks,

Ken

 

Ouick ouestion guys,

What type of hydraulic fluid dhould be used to top off the resovoir for the soft top operation? Does It have to be Mercedes factory fluid or can I get something from the local auto parts store?

Thanks,

Ken

Ken, why top off your hydraulic fluid when it's 13 years old? Why not consider Hydraulic System Flush / Renew and you can use Febi-Bilstein 02615 which is the OEM of the MB product at a fraction of the cost. Trust me this has all been discussed at length in prior threads.

Your Parts Search Returned 1 Part(s)

Importec Parts Catalog - p/n L7070-97881

 

I just did the replacement yesterday, a very quick and easy job.

Don't see a reason for it not to be a Mercedes ZH-M one. The cost was minimal at 20 dollars or so for 1L bottle. Complete flush required two, one is more than enough to top up.

 

I believe that it is febi bilstein Z-HM 2615. but that's hard to find.

 

How hard to find is it? What I am asking is can I buy anything equivalent at Autozone or Advanced Autoparts?

Thanks

 

In a word, NO!!!!! Many problems down the road!!!! {so it has been said here} If I were doing mine, I would go to the dealer.

 

I will go with the Mercedes Benz Hydraulic fluid.
Thanks for the info guys!

Ken

 

Add me to the list.

As soon as I get my car back from the dealer from having its headlamp replaced and my new stainless braided lines put on, I will be doing this fluid flush. Looks pretty simple.

I already ordered the rubber-bulb battery filler and the OEM Mercedes fluid (less than $20/l) like lynns suggested, so it should be as mess-free as possible. It will also be interesting to see my spare tire for the first time. No joke, I have never been under there before. Lol. Kind of embarassed to admit it...

 

Let's not forget that with leaking cylinders you are flushing the system.

Regards.

aam.

 

Lol...that's certainly one way to look at it...

 

Better Flush

This is what my old fluid looked like. It had the appearence of graphite not clear or even cloudly like beer. After cleaning the container I put one bottle of "No Leak" and filled the container and flushed out the system till the fluid cleared out. Then I topped it off with more fluid. 10/01/2008

 

Just so folks can compare, the new fluid looks like canola oil. Mine looked exactly the same and was flushed with ZH-M for $14 a litre.

 

Just so folks can compare, the new fluid looks like canola oil. Mine looked exactly the same and was flushed with MB-Z for $14 a litre.

Or you can pay $9.49/liter x2+ship at Your Parts Search Returned 2 Part(s) = $29.00

 

Why you should flush the convertible top hydraulic fluid

Unless I missed earlier discussions, I see no mention of the danger of allowing moisture to get into the system. The hydraulic fluid is hygroscopic meaning that like brake fluid it absorbs moisture from the air. The polyurethane seals although resistant to moisture are not able to last forever and do fail due to exposure to water. Seal experts tell me that a combination of water and heat lead to a rapid kind of seal deterioration that resembles cottage cheese.

A picture of a top lock seal that shows the "cheese" like texture at the failure points is attached.

Others have pointed out in this forum that the original seal material is based on a subgroup of polyesters called polycaprilactones that have improved resistance to moisture and may be the reason for its use.

What all this may mean is that if you don't change your fluid as often as you do your brake fluid (two years?) you will have moisture in your system and probably are cheesing your seals both in the cylinders and in the pump.

You have not found any ph related threats so maybe we should shift attention to the water.

By the way, note that some later model Mercedes reservoirs have a big filter cap that appears to contain silica-gel. Ah ha Mr. Holmes, we may have a clue here.
For those that don't know, silica gel is used to absorb moisture.

Regards,

George Anderson

 

seal failure pix

picture of cheese failure. Seal life unknown

 

Thoughts on how flushing works on this hydraulic system. (Based on the service diagrams)

I think the system flushes each cylinder to the reservoir on both strokes of the piston. A short way of saying it is on each stroke, the unpressurized side of the piston is connected directly to the reservoir. By working the cylinders several times, you should change out the fluid if you are catching the return flow in a jug and not letting it back into the reservoir.

George Anderson

 

Does it have to be Febi-Bilstein hyd fluid? Or would any good brand of hydralic fluid work?

 

I have long wondered this. It would be nice if we could use some other fluid that has anti-moisture properties and doesn't eat up the seals...

Everybody has always told me you have to use either the MB fluid or the febi, though.

 

Fact, Mercedes hydraulic fluid Part#000989910310 is not at all like brake fluid which is hygroscopic. The Mercedes hydraulic fluid is nothing more than Mineral oil which is not hygroscopic or does not attract moisture. Hydraulic fluids are a large group of fluids. I believe when one mentions hydraulic fluid we automatically
think of brake fluid. If it were like brake fluid it would destroy our seats and painted objects ect.

Brake fluid is a subtype of hydraulic fluid with high boiling point and low freezing point. It is hygroscopic, so that it will absorb water which could otherwise cause corrosion of brake system components.

From Wikpedia

Mechanical and industrial

Mineral oil is used in a variety of industrial/mechanical capacities as a non-conductive lubricant. Refined mineral oil is used as transformer oil. Electric space heaters sometimes use it as a heat transfer oil, and it can be used generically as a coolant in electric components as it does not conduct electricity.

Because it does not absorb water from the air, mineral oil can be used as an automotive, aviation, and bicycle brake fluid.


Used as a Preservative

Since it does not absorb atmospheric moisture, mineral oil is useful as a protective coating or bath for water-sensitive materials. Mineral oil is also often used as a coating on metal tools and weapons, knives in particular, as a way to inhibit oxidation.

Last but not least, I would change the hydraulic fluid at least once a year due to the small particulates in the oil from use. Mercedes Benz of Ft. Lauderdale has the OEM Part#000989910310 hydraulic fluid for $11.31 plus shipping.

 

Fact, Mercedes hydraulic fluid Part#000989910310 is not at all like brake fluid which is hygroscopic. The Mercedes hydraulic fluid is nothing more than Mineral oil which is not hygroscopic or does not attract moisture. Hydraulic fluids are a large group of fluids. I believe when one mentions hydraulic fluid we automatically
think of brake fluid. If it were like brake fluid it would destroy our seats and painted objects ect.

Brake fluid is a subtype of hydraulic fluid with high boiling point and low freezing point. It is hygroscopic, so that it will absorb water which could otherwise cause corrosion of brake system components.

From Wikpedia

Mechanical and industrial



Mineral oil is used in a variety of industrial/mechanical capacities as a non-conductive lubricant. Refined mineral oil is used as transformer oil. Electric space heaters sometimes use it as a heat transfer oil, and it can be used generically as a coolant in electric components as it does not conduct electricity.

Because it does not absorb water from the air, mineral oil can be used as an automotive, aviation, and bicycle brake fluid.


Used as a Preservative

Since it does not absorb atmospheric moisture, mineral oil is useful as a protective coating or bath for water-sensitive materials. Mineral oil is also often used as a coating on metal tools and weapons, knives in particular, as a way to inhibit oxidation.

Last but not least, I would change the hydraulic fluid at least once a year due to the small particulates in the oil from use. Mercedes Benz of Ft. Lauderdale has the OEM Part#000989910310 hydraulic fluid for $11.31 plus shipping.

Ron,

I do not agree with your attempt to suggest that the mineral oil used in the soft top system is not hydroscopic. It certainly is, but not because it has the same chemistry as brake fluid. If you check the MSDS for the Bilstein approved fluid you will note that it is not pure mineral oil at all but contains additives. Some of those additives are emulsifiers etc. similar to what is added in motor oil.

Before you reply with more opinions and definitions, please take some sample fluid, add water and shake. If it looks cloudy, congratulations, you have a mixture of mineral oil and water. Pure mineral oil and water would show two distinct layers and will not mix.

Old oil taken from a high time vehicle is frequently cloudy as has been reported elsewhere.

It is undeniable that water vapor enters the system continuosly through the reservoir and if allowed to stay in the liquid state (condensed) will rust stuff in spite of the oil being present.

Finally, I would remind others that citing the Mercedes no change rule can't trump my experiment.

Regards,


George Anderson

 

Try p/n 0009899103 Febi-Bilstein 2 liters for a shipped total of $29.89 from AutohausAZ Search Returned 2 Part(s) or try Mercedes Benz of Fort Lauderdale for a total of $38.68 because of s $6.00 handling fee.

 

Guys lets not get in to a pissing contest.
Replace the fluid after a few years like everything ells,
it is not going to brake the bank.
I always have two extra liter cans in my storage.
Same oil for is for the hydraulic suspension and the top.
It is cheap insurance, you do no harm by replacing fluids,
even if is not needed.

Regards.
aam.

 

Does anyone know where to buy Febi 02615 off the shelf in Vancouver? BC? Canada?

Thanks.

 

Does anyone know where to buy Febi 02615 off the shelf in Vancouver? BC? Canada?

Since I have been on this forum I have yet to hear of anyone finding Febi 02615 on the shelf in the US or Canada. You will need to order it from your local MB Dealer at a premium if you want it off the shelf.

I would suggest p/n 0009899103 at $9.49/Liter plus shipping to Canada

 

What type of no-leak product did you use, and how much did you add to the system?
Regards,
BOB

 

Welcome to thr R129 forum!

Bob, please know that using ANY 'No Leak' product is just a stopgap and is not a true resolution to a hydraulic cylinder seal problem but if you want to no more please read http://www.benzworld.org/forums/r129-sl-class/1301281-no-leak-fixed-my-hydraulic-fliud.html

 

Use stop leak products and is going to cost you big time.
Reconsider.
Regards.
aam.

 

Thanks for the advice Lynns.
I'll do the hydro. oil change. Anyway I do not go much top down, too hot in the day when I'm on the road.
This is the best quality car I ever had, maybe just beside my old 1989 300SE.

Regards.

IMHO, all the more reason to do the RST oil change. If the oil just sits there in the kind of heat that you have WE have determined that this may contribute to the degridation of the HC seals.

Let us know what kind of color the oil is when you first take a look at it compared to the new clear oil. Pictures would be even better.