knowbenz

Posted this in AMG section but figured I would post here also incase some were interested since this problem happens with all R230 Sl. The same valve blocks can be found in CL500 CL55 CL600 CL65 S500 S55 S65 Sl65 SL600 SL500 with ABC suspension

So I helped a friend of mine with a 2004 SL55 reseal one of his ABC valve blocks. His car would lower the front end after sitting for a few hours. He had tried getting the fluid flushed and new filter but it didn't help. He asked me to take pictures along the way so I thought I would share.

First step was to remove the valve block from the vehicle. I didn't take any pictures along the way but these are the tools I used minus a 17mm and breaker bar to remove the LF wheel
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Be sure to clean the surrounding area really well before removal to avoid getting any dirt into the lines

Here is the valve block out of the car, excuse the paint markings in the wrong spot as I quickly put the valves back in for a picture but put in opposite spots lol
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First step is to remove the plastic clips that hold the valves together. How I usually do this is to release one tab on one valve and turn it out of position so I don't have to fiddle with two sides at once, the turned side will be off of the lock tab that holds the clip in place. Here is an overhead view, notice it is only slightly turned. If you turn it too much it will be difficult to remove the clip.
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Once it is slightly turned I use a small screwdriver to push the clip out of the way and place another small screwdriver under the base of the clip to put a little pressure upwards
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From there I leave one screwdriver underneath the clip and then loosen the clip on the other side of where that screwdriver is. once you push the clip off the lock it tends to move up and then I put the little screwdriver underneath and work it up from side to side
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Do the same for the other pair of valves. For the locking valves I use my hand for the upward pressure as the clip is in the middle of the valves. From here you can rotate the valves 90 degrees on the control valves and about 45 degrees on the locking valves and then they can be pulled out of the valve block.
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The big O-rings at the base of valves just seal outside moisture and such from getting in, They are not under hydraulic pressure so if they look a little dry it's OK. I have seen the tall ones replaced by using two O-rings, or using one O-ring and a small bead of silicone around the outside. Either way works.

I have never replaced or seen replaced the fat greenish blue O-ring on the shaft of the locking valve, I usually give everything a good cleaning and put the plungers back in with some new hydraulic fluid as lubricant. The springs on the plungers can be removed, I squeeze them to get a feel of strength, never had to replace them, I usually give them a little stretch to make just a hair longer incase they have become compressed over time.
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Inspect the white teflon spacers for any kind of damage, these rings don't offer any sealing, they mainly offer support to the sealing O-ring to help keep it in place. If they are damaged they can be replaced with rubber o-ring. The rings on these valves were in good shape so They just got a good cleaning with a tooth brush and a little solvent.
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Here is a few pictures of the valves with their respective seals that will be getting installed after the valves receive a thorough cleaning. I didn't take pictures but I always like to apply power to the control valves in both directions and run solvent both ways through the passages just incase some gunk is caught up inside the valve. Also be sure and thoroughly clean the aluminum housing to get all old fluid and debris out of it.
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After it is all cleaned up and new O-rings installed it's time to put the valves back in. I use plenty of new hydraulic oil to lubricate the valve with o-rings as well as the valve block itself. I always try and turn the valves in clockwise, sometimes the valve comes loose from housing turning the opposite way. Take your time putting them in to ensure you don't pinch an o-ring.
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Once all valves are in place it's time to put the clips back on. Simply push the clips in between the valves and down into position.
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Double check you have 14 old o-rings and no new o-rings on your workbench. After that put the valve block back in the car.
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AmgSeahawker

Awesome write up! Where did you get the o-ring kit?

knowbenz

Ebay, item number 152254742106. That one doesn't have square o-rings. He has another listing that comes with the square o-rings if you need them

compaddict

iTrader: (1)

Thank you very much!

Hary Gahtoe

It's good to hear your friend has pressure but as someone who still has the dreaded front squat issue, each car has individual problems and needs replacements tailored to those issues.

One thing I noticed about the O ring set from eBay; there isn't replacements for the flat sided o ring spacers. Mine were in worse shape than the actual o rings.
Also the brass plungers inside the solenoids have large flat faced(blue in color) o rings which don't seem to readily available.

I've yet to see a full set of true metric sized o rings here in NA but
there is a firm in the UK that offers an ABC replacement seal kit and it doesn't offer the blue flat seals on the plungers either.

knowbenz

That seller has a kit available with the flat square cut o-rings/spacers eBay item Number152257638336. I have replaced them before. I usually evaluate case by case if it needs the square cut ones or not. Personally never replaced the blue o-ring on the plunger, the only purpose I see is to keep fluid from the backside of the plunger. I'm not an engineer so I can't be certain. But I've revealed plenty of valve blocks with great success

carguyshu

those flat cut o rings are larger than the sealing orings and as a result the square edge gets caught as the valve goes up and down and wears quickly. The square rings will then send debris everywhere. I just took apart a valve block with hardly any miles on it that had this exact issue. You're better off either just trashing the block or trying round cut rings for spacers.

carguyshu

Here's what I'm talking about

knowbenz

Either I'm not reading this correctly or it doesn't make any sense. From the factory the teflon square cut rings are not larger than the sealing ring. They offer support. Later valves have rubber square rings in them. Those rings do not move as the valve moves. When the solenoid activates the plunger in the middle allows fluid to enter the inside of the valve and out the little holes around the shaft. The only time those o-rings move is during installation. The little blue seal on the shaft of the plunger moves but doesn't seal the fluid from moving through the functional part of the locking valve if that makes sense.

knowbenz

From the looks of this it seems the square o-rings used were too large and a portion got shaved off during installation. I could see how this will make your front droop. If they are too big and get a little shaved off then the seal is compromised, if the o-ring is too small then the seal is compromised. The only way the front will droop outside of a leaking strut is the fluid leaking through the locking valve when it shouldn't. It can leak past those o-rings letting the pressure bleed down, or through the internal passage of the valve with from debris in the seat of the plunger not allowing a full seal or the spring is too weak and letting some pressure through.

knowbenz

Here is an easy to understand picture of what the spacer ring or backup ring is supposed to do

carguyshu

right, the problem is the square cut orings that come with those kits are larger than the sealing orings and stick out further than the round sealing orings. As a result they get sheered off and put a ton of contaminants into the system.

If your original square spacer rings are intact, then simply replacing the round sealing ones will work. If those square ones are not intact the rebuild kit won't help you as the square o rings are larger than the sealing orings.

knowbenz

The kit this user sells has proper metric size that doesn't get sheeted off on install. I know which ones you are referring to, when you install all the rings there is zero room for expansion of the rings due to compression of installation. This kit still leaves room being that the spacer rings are the correct size.

knowbenz

Thought I would throw this up here also. Did a second valve block using the square o-ring kit. The first one with square o-rings I did and the one from the first post on this thread are still holding up great. Pretty much everything is the same except for cutting off the teflon rings and replacing with a rubber square cut o-ring.

These didn't necessarily need to be replaced as the condition looked good. I started off by measuring all the different spots on the solenoid just to compare with the new rubber square rings. I've seen a kit before that that square rings were way to big and got cut upon installation.
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I used a razor blade to cut the teflon rings off, they can also be removed like the o-rings with a seal tool or pocket screwdriver.
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Here is everything being replaced with this kit, x2 for the other pair of valves not pictured
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Install the new o-rings starting from the biggest side and go down in order. It is sometimes difficult to get a square o-ring around the round o-ring. Do one valve at a time so you don't forget the order they go, or just refer back to this thread.
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As you can see the square rings don't protrude past the valves surface just how the teflon rings don't. Also, what is hard to capture on camera is that there is a slight amount of room left between the seals to allow for expansion of o-ring when the main o-ring gets compressed which is the same with the teflon rings installed.

The other setup I have seen has square rings that are damn near the same diameter as the round o-ring which makes installing the valve extremely difficult and ends up sheering off a few thousandths from the square rings and leaving loose rubber debris to make it's way into the hydraulic circuit.

One thing i want to stress is to make sure the square o-rings don't roll over when installing, it's easy to miss a small section that may not be fully seated and has to be rolled a little more. I found this out the hard way, the top seal on one control valve wasn't fully in place so when I went to install it it got cut. I should have rechecked when I realized this one was being a little difficult to get seated. Use lots of lube and twist back and forth the slight amount that it will to seat everything. I contacted the seller about the o-ring I broke and he asked which one it was and dropped one in the mail the same day. I should get it tomorrow and have this valve block wrapped up.
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mercy-me

Very important point! I just did my front valve block with new seals due to left front "ABC Warning" on rare occasions. I read all I could find on the reseal but never found any instruction to turn the big valves 90° instead of 45°. I struggled until I accidentally turned the big valve another 45° then it came right out.

I purchased my o-rings and backups from Orings and More.....................





This is the best write-up yet!

Many, many thanks,

Bob

moretech

This is a super good thread and write up but I just have one question. You mention the square cut o rings but in the picture they do look "round". So I guess if I were actually doing this repair I'd be a bit confused. Especially with the repair kit as they are all black. What am I missing on this great post.

moretech

knowbenz

so in the first post, the square ones are white teflon rings. When you see them in person it is obvious which ones are square and which are round

the site has some more pictures and infor www.diybenzrepair.com

MRCL65AMG

Are the front and rear valve blocks the same or is one smaller?

carguyshu

they are the exact same and interchangeable.