R230 ABC Rear Valve Block / Accumulator removal Procedure - Mercedes-Benz Forum

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post #1 of 55 (permalink) Old 09-09-2013, 11:11 PM Thread Starter
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R230 ABC Rear Valve Block / Accumulator removal Procedure

Hello all, I searched but found no info regarding removal of the rear Valve Block on a R230 (anywhere on the 'net). As removal is necessary to change the two rear Accumulators as well as service or clean the rear Valve Block this procedure will be necessary at one point or another in the life of many of our R230's:

Time: With car on stands and wheel off ready to begin removal about 1 hour

Two notes:

1) It is absolutely crucial to keep the work area, hoses and valve block clean and free of any dirt at all times! Even the smallest particle of dirt introduced into the ABC system can cause system failure. IF you do not plan to remove and clean the Valve Block Assembly I strongly recommend purchasing an assortment of hydraulic plugs (IE Capplugs.com) so you can immediately plug the port in the Valve Block as soon as a ABC Hose is removed. Cap plugs should be available at any facility that deals with hydraulic hoses or fittings.

2) It is in no way necessary to place any undue stress on any of the ABC hoses to remove the Valve Block Assembly. No prying, pulling or twisting is necessary! Please handle all ABC Hoses with care so you do not end up with a leaky hose which requires replacement!

On to removal:

I had a tool that made removal a breeze. I consider this tool necessary to remove the valve block assembly. I see no way to remove the assembly safely without it:

Snap-On 17mm Crows Foot: FRHM17

A similar crows foot may work but, this is the exact tool I used and removal was a snap. If you don't have one, you can call or stop by any service shop and ask any tech for the number of the local snap-on distributor. Alternatively, a parts store or Craftsman crows foot may work.

Here are the primary tools I used for removal:



All ABC Hose Fittings requiring removal to remove the Valve Block are 17mm.

The short 17mm wrench is a wrench I cut down long ago. This helped in removing one of the ABC Hoses but, I don't consider it crucial to the job. As with any hydraulic hose you MUST use a wrench designed specifically for removing hydraulic lines. Failure to do so will likely result in a rounded off ABC Hose Fitting and possibly necessitate replacement of the entire ABC Hose! The standard wrenches above were used for ease in loosening and removing the ABC hoses only after they were initially broke free using one of the Line Wrenches.

First, all 4 corners of the car were up on jack stands. While the Valve Block Removal procedure could be carried out with just the rear of the car up on stands I will be working on the front Accumulator as well so, the car was in the air. I mention this as having all 4 wheels at full droop completely depressurizes the ABC system (after about 15 minutes in the air).

To be safe, I also loosened the rear left ABC valve:



I loosened this fitting slowly and there was some pressure released along with minor fluid loss. Place a drain pan under the fitting and Loosen slowly!

Move the drain pan below the Valve Block Assembly. Clean the entire area (any dirty hoses, Valve Block and Accumulators) with Brake Clean then blow off with compressed air. Air in a can is fine if you don't have a compressor handy. Wipe down any excess with a clean rag.

First, remove the 10mm nut securing the hose retainer. This will allow for extra movement in the hoses while disassembling.



Remove the first hose:



As you can see the Crows Foot is a perfect fit for hose removal. Break the hose free then use the crows foot or your fingers to remove.
As soon as the hose was removed from the Valve Block I cleaned the fluid off with brake clean on a rag, then wrapped the hose end with saran wrap and tape to insure no dirt enters the hose. If you are not planning to disassemble and clean your Valve Block install a plug in the port immediately to keep dirt out.

2nd hose, the other end of this hard line:



Again, the crows foot sneaks right in with a short extension. This end attaches to the small Accumulator junction block.

Remove the short hard line entirely and block both ends.

On to the next hose:



Again, wrap with Saran Wrap and tape/block the hose end and also the port in the junction block if not planning to clean it.

And the next one:



This fitting was difficult to photo but, the crows foot slid right in. No issues here at all.

And now moving to the 1st hose on top of the Valve Block:



It's a little tight removing this hose once the fitting is removed from the Valve Block. Clearance is at a minimum between the Valve Block and the Accumulator. I found the hose much easier to safely maneuver when grasped from below with one hand then the top of the hose maneuvered out and away with your other hand:



Once that hose is safely removed proceed to remove the rear hose:



Here I had already broke the fitting loose with the line wrench and was proceeding to loosed the fitting with the stubby 17mm. If I did it again I would remove the top nut securing the entire assembly to the car (via the rubber insulator, just above the large accumulator) and carefully try to slide the entire assembly out a little bit and get a hand in there to loosen the fitting by hand. It was a real pain loosening the fitting even with the short wrench. There's just not a lot of room in there. With all the other ABC hoses removed at this point it's likely you can slide the entire assembly part way out.

I mention above the entire assembly slides out on the bottom. Here is a good pic showing the slide mount:



Once you have removed the top rear hose in the step above you are ready to very carefully slide the entire assembly out of it's cubby. Be sure to clear the way of the ABC hoses you have removed and you don't pull on any wires connected to the Valve Block. Slide the Assembly just enough to reach each electrical connector to disconnect.

I took a picture of the electrical connectors as they attach to the Valve Block:


Here is the assembly removed:

Finally, the entire assembly removed from the car:



That's it!

Hope this helps,

Brian

Last edited by vtvette; 09-10-2013 at 11:29 AM.
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post #2 of 55 (permalink) Old 09-10-2013, 03:45 AM
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Good Post

Brian, thanks for the informative pictorial. Please give us more information in regards to the necessity of this type of repair. What symptoms were you experiencing? Any warning lights? What year car? (please fill out your profile). How did you complete the repair? To the dealer for a "Rodeo"? Or another method? It's great to see that someone in the R230 forum is actually working on their car and creating a post with pics, we need more of this. I currently have a 2009 SL550 Silver Arrow Edition with 24k on her and I have an extended warranty. So I probably won't be posting any type of repairs soon, although after being an old MB/ Porsche tech many years ago, I still enjoy tinkering and would enjoy creating a repair pictorial to post. Keep up the good work.................Thor
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1971 350SL 4-speed stick- sold
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Last edited by Thorgod; 09-10-2013 at 07:39 PM.
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post #3 of 55 (permalink) Old 09-10-2013, 03:58 AM
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kudos for the great write up.....
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post #4 of 55 (permalink) Old 09-10-2013, 11:09 AM Thread Starter
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Hi Thor, Profile Updated thanks for the tip. I actually wrote this procedure up for a gentleman on another Mercedes Forum as he is changing out his Rear Accumulator this week and could find no how-to on how to do this. I figured I'd throw it up here as well as I frequent both forums.

My car is a 2005 SL55 AMG.

This *should* apply to all R230's 2003 to I *believe* 2009. I know it applies through 2007 but, I am not as familiar with the changes made to the later years.

Note there are two Valve Block/Accumulator assemblies on the R230. One is for the front suspension and is located in behind the front bumper cover, in front of the Front Left wheel. This one is quite accessible and there are numerous write up's on line regarding removing and servicing this unit.

The second is the rear Valve Block Assembly I have covered here.

There are a number of reasons one may need to remove the rear Valve Block Assembly from the car. The primary reasons would be to change the Accumulators or, clean (or replace) the Valve Block Assembly.

The Accumulators: These are the black balls you see on my removed assembly. The accumulators consist of a rubber bladder in the center separating a rear chamber of Nitrogen Gas from the front chamber which fills with ABC fluid. The purpose of the Accumulator is to absorb rebound in the suspension system through pressure on the fluid (similar to the way a shock insert dampens rebound in a conventional McPherson strut assembly).

Signs of a bad Accumulator are a harsh ride (I've heard this described by people as the car riding link a tank). The Accumulators fail by the rubber membrane deteriorating over time. This is bad as it can contaminate the ABC system with small chunks of rubber from the deteriorating membrane. It seems from forum research these rarely fail all at once but, rather ride quality deteriorates over time into a harsh, poor handing ride.

There will be no warning lights when these fail.

The best way I've found to test the accumulators is the simple bounce test. Go out to your car and with the engine off push down firmly on the bumpers. The car should be near rock solid. If there is any bounce or rebound than your accumulator is compromised.

My car has 97,000 miles on it. I purchased it recently. The other day I started the car and had ABC fluid pouring our the fill cap and dipstick tube. I have found other forum members report this problem but, no one had a definitive answer as to why. For some the problem simply "went away" while other performed a fluid flush/fill and rodeo and this corrected the problem. I believe the problem of ABC fluid out the reservoir cap or dipstick tube may be caused by a failure of the nitrogen bladder in a ABC Accumulator pressurizing the system. With 100,000 miles I planned to change all my accumulators as preventative maintenance anyway. Genuine Mercedes Accumulators run about $130.00 on line or, about $200 from the dealer.

Valve Block - the Valve Block is interesting. Seems more than a few of these have been unnecessarily replaced by tech's who don't have a clear understanding of their function or operation. The most notable failure of a Valve Block is one corner loosing pressure and the car sinking over a relatively short period of time (a few days without starting). Even a tiny piece of dirt can keep the block from maintaining system pressure, allowing ABC fluid to leak out of the strut back into the system and cause that corner to sink.
While replacing the Valve Block will certainly remedy the issue it may be unnecessary. The valve block can be removed, disassembled and cleaned as per these instructions:

http://www.benzworld.org/forums/w215...lve-block.html

There are numerous other write up's and even some youtube vid's I believe if you look around.

**Please note** I am not a Mercedes Tech, I am simply sharing my finding with others here in a hope to spread knowledge.
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post #5 of 55 (permalink) Old 09-10-2013, 11:22 AM Thread Starter
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One more note: Surprisingly little fluid is lost when removing the Valve Block Assembly. Changing the Accumulator on the front of the car does not necessitate removal of the valve block and results in even less fluid loss than servicing the rear. Once the assemblies have been reinstalled and the car is back on the ground top off the ABC fluid reservoir and have an assistant use the raise/lower button to raise and lower the car several times while you top off the ABC reservoir with fresh Pentosin CHF-11s.This may take a little time but negates the need for a Rodeo. NEVER run the engine with an empty ABC reservoir!! The pump may ingest air which will kill it in short order!

However, if it has not been done so recently I would *strongly* recommend a complete ABC fluid flush and fill while servicing the valve blocks/accumulators. This is the cheapest insurance you can buy against future ABC failures. While Mercedes has no recommended service interval for the ABC fluid most agree that 60,000 is an ideal range. I will likely change mine out every few years. It's a relatively simple process and requires no special tools, equipment or rodeo. Search "ABC fluid flush" and you will find much info and even youtube videos on how to do this.

I have ordered a Star Diagnostic setup from Mackhack here on this forum as I consider it an indispensable tool for servicing any modern Mercedes but, it is not completely necessary for the procedures outlined above.

Last edited by vtvette; 09-10-2013 at 11:25 AM.
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post #6 of 55 (permalink) Old 10-06-2013, 11:28 PM
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Hi Brian.

Good writeup, but you could have saved some of your hassle.


The four rubber covered hydraulic hoses have a quick snap connector.
With the tool w230 589 01 33 00 and w221 589 01 33 00 they can be disconnected very easily.

Cheers, Frank
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post #7 of 55 (permalink) Old 10-07-2013, 12:43 AM Thread Starter
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Quote:
Originally Posted by Frank_S500 View Post
Hi Brian.

Good writeup, but you could have saved some of your hassle.


The four rubber covered hydraulic hoses have a quick snap connector.
With the tool w230 589 01 33 00 and w221 589 01 33 00 they can be disconnected very easily.

Cheers, Frank
AAHHHH!! I actually suspected this when the hoses swiveled at that point!
That would truly make the procedure of removing the valve block very, very easy!

The tools would be money WELL spent for someone looking to remove their ABC Valve Blocks

Thanks for this info and contributing the part numbers to this thread Frank!
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post #8 of 55 (permalink) Old 10-08-2013, 08:29 AM
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I think my 2003 SL500 has this problem, in the meantime I'm trying to figure out what I want to do with it
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post #9 of 55 (permalink) Old 10-08-2013, 03:04 PM Thread Starter
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Originally Posted by MercedesSL5002003 View Post
I think my 2003 SL500 has this problem, in the meantime I'm trying to figure out what I want to do with it
I assume the rear is sinking over a period of time? How quickly does it sink?

I've heard a rodeo/fluid flush *can* help but, results do seem to vary.

What are your symptoms?
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post #10 of 55 (permalink) Old 10-09-2013, 07:04 AM
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It sinks on the drivers side, it started doing this a couple of months ago but it would only happen a couple of time a month. Then about two weeks ago I drove it to work and I got out of the car and their was hydraulic fluid coming leaking forming a small puddle. I turned the car off and popped the hood and their was fluid all over the right side of the engine bay looking like it had been spraying. I checked the hydraulic fluid levels and everything was good. I drove it home and the front made a squeaky sound and I parked it and have not driven it since except around the block to see if anything changed and this time it didn't leak, it won't leak when the engine is off.


Quote:
Originally Posted by vtvette View Post
I assume the rear is sinking over a period of time? How quickly does it sink?

I've heard a rodeo/fluid flush *can* help but, results do seem to vary.

What are your symptoms?
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