hydrogen

Hi,

I am new to this site but have read a wealth of information on the site from some very knowledgeable contributors. If I want to know anything about my car this is my first stop.

I have an SL500, 2005, 7 speed, Australian compliance.

Great car love it, however, after about 3 days the front left suspension (passenger on my car) has sunk down noticeably. Then over a longer period of time say 7 days, the front right suspension (drivers side on my car) also sinks down, but usually not as far as the front left. The rear suspension is fine. I will sometimes have the read ABC error, 'car to low', but when I start the engine put it in drive the car rises up and the error disappears.
There is no ABC fluid or leaking that can been seen and no fluid underneath the car.

About 6 months after buying the car I noticed this problem, but it used to take about 2 weeks for the front left suspension to sink down.

I have been told by a MB dealer mechanic, about 12 months ago that the ABC pump is a bit noisy.

I have had the sinking problem to my mechanic, not a MB dealer, he doesn't think it is worth worrying about too much. He says there are no leaks and the reservoir is full. He did suggest that the fluid in the front left and later front right is running back into the ABC reservoir.

I would like to resolve this issue. I have read some contributions on this site that talk about ABC problems and have realized that there is a diagnostic sequence that you go through to determine what or where your problem lies.

I would appreciate any assistance or directions with this problem.

Thanks.

Ghostty

Well, my friend, i think your mechanic is wrong.

If the car is sinking in the garage after 3-4 days then it's a problem.
He is right, though, there is no leakage of the system outside, since the reservoir is full.
But it happens to have a internal leakage - what happens is when the pump levels the car the fluid goes back due to a bad O ring. The fluid goes back in to the system - out of pump, pressure goes down and the car sinks. It happened before, i read about another pal on this forum about it. Can't recall exactly how did he fix it.

So if you're interested in fixing it, that's where i would start. The wheel where the car sinks shows you which corner to start with. Search the forum for a topic about internal leakage, there should be some info on that for sure.

Best wishes

hydrogen

Thanks buddy, I will mention that and make that search you suggested.

kbob999

Your front ABC valve block has dirty valves, or blown o rings, allowing the front to lose pressure over time and settle.
3 solutions in order of cost and degree of success are: flush and replace ABC fluid; rebuild the front valve block; replace the front valve block. There are members here that make a job of rebuilding valve blocks. You can search for them here or Benzworld forum.

funymuny

My 2004 had this 'sag' issue. If you flush/replace ABC fluid do not be surprised if the sag issue actually becomes worse...due to contaminants being moved in the valve. I had someone rebuild my front valve, which is basically taking it apart, cleaning and replacing the valve seals/o-rings. That solved the problem. As long as the car is adjusting/leveling when you start it seems unlikely to be a pump issue. Leaky valve is a known 'maintenance item'. This is a maintenance item that MB never mentions and that contributes to the fears and bad reputation of the ABC suspension.

mercy-me

See attached DTB for acceptable sagging per MB. Also attached is a troubleshooting guide which will help to better understand the whole system.

I agree with Funy, flush first and if no help then a valve block rebuild should bring you into acceptable limits.

Good luck,

Bob

hydrogen

Thanks gentlemen for your advice and information much appreciated.
I think you are right, a valve block contamination problem, I think will probably need reconditioning, cleaning o rings done etc.
thank you again.

SL55Cowboy

I have the same issue also. But I think I can fix the issue. I am not sure about all the seals i could use to correct the problem. I read a post where I guy used seals from harbor freight kit to fix the issue. Does anyone know where I could purchase a seal kit to fix the issue. I am driving a 2004 SL55AMG. If i find the right I will post step by pictures of the job so no one else has to take their cat to the stealership!


Thanks SL55cowboy

mercy-me

Check out this thread from the W220 Forum. Jnash rebuilds the blocks. Don't know what he charges but I'm sure that it is reasonable. There are others I'm sure that rebuild, you just have to look in the other forums.

Good luck,

Bob

funymuny

That is who rebuilt my front valve on my 04. Rebuilt is too strong...refurbished, reconditioned, cleaned. He opened it up, cleaned it, replaced the o-rings, tested the solenoids, shipped it back. In the end I could probably have done myself but for what I considered a reasonable price someone who had done others did it. If you get someone to 'rebuild' it be sure to have them get pictures while it is open. Maybe before and after. Nash was supposed to give me some but said he forgot.

hydrogen

Thank you Gents. Your diagnosis was 100% correct, bad o ring in front valve block. All good now. Thanks again..
I am a newbie but this is a great forum for getting advice.

funymuny

Glad it worked out well for you. I believe this is an example where this car is much maligned by folks because, well, who ever heard of having to do this kind of repair, or maintenance, on a suspension system? The car sags and people seem to associate that with something being broken, poor design, etc. But if you think of this really cool active suspension as requiring some maintenance and repair then it has a different perspective, or at least that is where I wound up. Now, when one of the high pressure hoses bursts and I have smoldering fluid underneath my car maybe I'll change my opinion. This line of MB's are not Toyota Corollas, no offense to Toyota Corollas...just built for a different purpose and different market. Mark

moretech

I would like to know if I let my sl500 set unrun, for say 3 months, just how low can it go?? Would the tires touch the bottom edge of the wheel wells if steering wheel is straight on?


moretech

mercy-me

Unless you have oversized tires or wheels then even if the suspension fully sags, the wheels should be able to be tucked into the wheel wells without issues.

I let my car sit from mid December until the first of April with not sagging although I did start it up about every 4-5 weeks. In my earlier post, some sagging over time is acceptable per factory specs as static fluid could work its way passed the o-rings in the valve block over time.

My personal opinion is that too much is made of the potential sagging issue. Afterall, this is a high pressure hydraulic system with all the inherent benifits as well as the inherent maintainence issues.

Go a head and park it and forget it.

Good luck,

Bob

Slpwr

hiI have the same sort of problem in my 2005 sl too , front rear left sagging , anyone recommend a Melbourne mechanic to me ? Thanks

Lee Wireless

Here is the ABC repair kit part number for the ABC valve block on your 2005 SL500. Around $100 at the dealer. 2203201158

Ghostty

I think my time has come to dig into valve reconditioning. Front left sagging all the way down, ABC "stop car too low" message on dash. What am I looking at to start with? From what I read here I can still have the engone running, but not driving, right? I'll have to check more after work, when I'll come back.

moretech

Plenty of threads on this plus you tube video support. Main thing is do not get anything switched around when reconnecting. Label everything carefully before any disconnects. Other forum members have mentioned this important point in write ups. I have a bit of sag right front after a week but I've never seen that code your car throws. Thanks for that piece of information.

moretech

Ghostty

Will the engine running damage anything? Or as long as it doesn't move the car I'm fine? I read on a thread that someone just used the rising function to push the ffluid through the system and it cleared the error. I am willing to try anything prior to actually take it apart

moretech

The way I read this is no problem at all. I put my car in gear, it levels off and off I go. Car runs fine once in gear, the leveling (larger 2 valves) valves keep it up. And, yes, I can level off by pushing the button one time, it pumps up and off I go. Then I switch back to lowest level. I have read from others just that it goes down does not hurt anything. It's just irritating to look at it like that. Where you really have a headache is if it starts going up and down while driving. There you see a wheel rising and lowering while in motion. There you have a larger leveling valve not doing right. That you need to fix on that real fast. I think you will see a bunch forum members in on the topic. Pretty common but your the 1st member I've read who sees total drop up front. The check (smaller 2 valves) valves must have really shot "O" rings . Still this is not a hard job as I have read to repair. You can buy, if you want, a brand new complete valve assembly for around $1400 from Husker but few do this.

moretech

Ghostty

Basically what happened is I did the abc flush like 2 weeks ago - all good. Then I took it for a ride in mountains, that's a week ago. And last night I noticed it's down all the way. No message until this morning. But yes, probably are the o rings, since there are no leaks nor drop in level in the reservoir. I just don't have the time now to deal with it and am going on a trip in 2 weeks, so the car might be sitting like this for 2 months...

moretech

If both dropped at the same time and neither one was before I want to think a bit more. This has been a gradual thing for me over many months/or years. Let us see what other members may respond. I wonder about a loss of electrical signal to the check valve to close properly when engine is off or the valve does not operate electrically due to an internal failure. Perhaps another member may comment if the STAR diagnostic system can tell if there is an electrical failure in the valve.

moretech

Ghostty

Both? Only the front left (driver side) sagged. Just got home, started the car, hit the raise button - car back to normal. Took for a spin around the block - so far so good. Will let it sit till morning and i'll check again. I do have a friend with a diagnostic system (not STAR) that he used on his CL500. Will stop by him and have him read for any stored codes. Who knows... The idea that fresh oil is more "thin" comparing to the old one makes sense to drop 2 weeks after fluid change, but who knows...

moretech

Somehow I got confused that both sides dropped--sorry about that. I am glad you got it up!
I've flushed mine twice but not any change in drop rate from either one. I doubt fluid viscosity is your problem if you get an overnight drop to a warning code. Could be a complete broken "O" ring on the short valve left side I suppose. Best of luck to you. Let us all know how it turns out.

moretech

moretech

Read this sometime, it's the best ABC overview. I've virtually have memorized it over the past 2 years with my SL 500. All the best to you on getting your car running great again.

http://mercedes-abc-drive-carefully....y-part-of.html

moretech