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Over the last couple weeks, I have been getting an intermittent white "ABC visit workshop" fault on the MFD. It normally occurred after the car had sat without being driven for a couple of days. I also noticed the drivers side front strut dropping a bit after sitting and upon startup, I could feel ABC raise it.
The other day, after a short drive, I left the car in the drive way. Soon thereafter, I noticed a puddle around the front left side tire. I thought it was the strut, but I am not so sure. Below are a few photos.
Photos 2 and 3 are looking toward the front left corner of the car. I noticed some hyde fluid on the left air snorkel as well.
I plugged in the Star/Das and only found a stored code for ABC. Code C1531-004, Left rear strut moves although locking valve is closed.
I was thinking about topping off the ABC fluid reservoir, then starting up the car and search for leaks. Any help is greatly appreciated.
Hey Curt,
have you changed out your accumulators? If one goes, often it will release its gas (nitrogen?) which causes a bubble and then a small over-flow of the the abc tank. not too uncommon
you may want to pull LF tire's rear inner wheel well ... I had a hose let go there .
time to look for a leak ... if you can not find one, then you likely lost an accumulator. You can confirm this by seeing if your parked fluid level vs running fluid level swings noticeably more than the lines on the dipstick
Cheers,
Chris
Last edited by latemodel21; 07-13-2016 at 03:47 PM.
Hey Curt,
have you changed out your accumulators? If one goes, often it will release its gas (nitrogen?) which causes a bubble and then a small over-flow of the the abc tank. not too uncommon
you may want to pull LF tire's rear inner wheel well ... I had a hose let go there .
time to look for a leak ... if you can not find one, then you likely lost an accumulator. You can confirm this by seeing if your parked fluid level vs running fluid level swings noticeably more than the lines on the dipstick
Cheers,
Chris
I don't think the accumulators have been changed. I had an extended warranty for 5 years and whenever I got an ABC warning, I took the car to the dealer. Got a new pump and valve block out of the deal. I suppose I could have had accumulators changed and did not know it.
I will pull the left front tire and start looking for leaks. I am guessing it is safe to start the car while looking for leaks? I think I will turn off my ELM and maybe raise the car as high as possible just in case it ends up going on a flatbed.
Don’t know much about the ABC system other than what is being discussed here in the forum …. it does not have the best reputation. My own car is going that way too ….. sinking ….. when it comes I will buy rebuild struts and give the system a makeover ….
But Curt – it could be anything … best to have it on a lift a have the leak 100% determined – always best with the correct diagnostic. Not to forget help from others in this forum
If when you start it up and drive and the height returns to stock then it's most likely a valve block leaking. With where the fluid is leaking I'd also check your motor mounts. When they go bad they leak in that exact spot.
If when you start it up and drive and the height returns to stock then it's most likely a valve block leaking. With where the fluid is leaking I'd also check your motor mounts. When they go bad they leak in that exact spot.
Thanks!
I will check the motor mounts. I am on my 3rd set. I'm sure the engine mods had something to do with it.
Based on the location at the rear of the LF, I'll provide what I would look at first. Pull the LF wheel and the fender liner first.
You may have the ABC line going from the pump to the left front valve block leaking.
This line takes the highest pressure, as the pressure spikes from the pump are reduced by accumulators by the time they get downstream.
If your SL55 is an earlier model, it has the 'pump' accumulator (1st in line) in the rear of the left front wheel well (where your leak is).
Newer models have the accumulator attached to the pump. But the line can still leak if this one fails.
If this accumulator has failed (usually the first to fail due to highest pressure) it is causing the pressure spikes to hammer the line there too. If the line is leaking, you may need to replace both line and accumulator. I would.
If the leak is from a line at the valve block to the strut, this would explain the car drooping. You should be able to see this leak from the lines at the valve block, but the location of the fluid says it is the front or main line, not the rear.
Some droop from leaky valves is acceptable to MB over time, and their service bulletins state this. My car has this happen frequently at startup, but only minor drooping/re-leveling.
If the fluid is puking from the canister, you probably need accumulators all around. This happens when the reservoir is topped up or filled after the accumulator bladders has failed. Then the fluid is passed back to the reservoir when the car is shut off. If your reservoir is suddenly low, and you have no leaks, you likely have failed accumulators.
Let us know what you find. It's good knowledge for all to learn from.
Last edited by kbob999; 07-14-2016 at 04:22 PM.
Reason: Added info.
I will check the motor mounts. I am on my 3rd set. I'm sure the engine mods had something to do with it.
A lot of places are selling non AMG motor mounts to AMG owners. They fit, but don't hold up. For the E55 and CLS55 the Cortico (OEM) part # is 2202402717 for the regular ones, and 80001089 for the high HP ones. Wouldn't surprise me if that was the case on the SL55 too.
I finally took a look at my SL today. I noticed the right front was was completely slammed. Other wheel heights looked about right given the lowering module. The ABC fluid reservoir seemed high. I then started the car and looked for leaks. Not sure if ABC is active when the car is in neutral. I saw no leaks. I then cycled the height adjustment a few times. Still no sign of leaks and nothing seemed extraordinary. It cycled without noise and was smooth up and down. Then I put the car in drive hoping for maybe an ABC warning. Got nothing. I then shut the car down. I never found any leaks. What I did notice was the reservoir was lower and I saw some air bubbles in the fluid. Not sure what this means. I am kinda thinking this is consistent with a blown accumulator.
I am a real novice when it comes to working on cars, but the help on this forum and DIYs like yours has motivated me to take on projects I never thought I could do. I have a STAR/DAS system which is a great help. I will dig up the WIS on replacing the accumulator and study it as well.
Thanks to everyone thus far. It gives me confidence to take on a project with everyone's help and I know people have my back if I get stuck.
I have an opportunity to put the SL up on a lift. The lift is about 15 miles away. Right now I am seeing no more leaks which I guess is still suggesting an accumulator burp was the source of the leak. If I top off the reservoir and maybe take some pentosin with me, is it safe to drive the SL to where the lift is or should I play it safe and put it on a flatbed?
(You probably already know this but...) Protect the tandem pump no matter what! if you run it dry it can implode internally and send shards of crap throughout the whole ABC system. I've read that can total the car because it's too expensive to repair.
No matter what, you need a proper diagnosis. My stealership blamed my car's "drooping" over night on a worn tandem pump (A $3400 repair in Canada). Replacing the pulsation damper fixed it and I replaced the front accumulator myself in a half day.
My stealership blamed my car's "drooping" over night on a worn tandem pump (A $3400 repair in Canada). Replacing the pulsation damper fixed it and I replaced the front accumulator myself in a half day.
Neither the pump, the pulsation dampener, nor any accumulator has anything to do with the vehicle dropping with the engine off. In this state all 4 of the control valves in both the front and rear valve blocks are closed, and this seals-off the struts from the pressure supply and return hydraulic lines. Only a failure of those valves or a leak at a strut or a line connected to a strut can be responsible for the vehicle losing height.
My understanding is that particles of worn o-rings can contaminate the valves and prevent them from sealing perfectly allowing the pressure to drop. This underlines the need to change the ABC fluid and filter occasionally.
Thanks guys. By the way, the single reason why I maintain my AAA membership is so I can tow the SL. It has had a number of rides on the flat over the years. Some are related to modification nightmares though.
I took the SL for a ride last night and all was well. Honestly, if the little burp wouldn't of happened in my garage, I wouldn't even know I have ABC issues.
just spent a good part of the morning reading what I have found to be the most comprehensive and comprehensible (for a novice like me) write up on ABC components, problems, diagnosis, fixes, etc yet. It may have been posted on MBW before, but does not hurt to post it again.
From the link I posted above is a trouble shooting guide to help identify one or more bad accumulators.
So how do you tell if your accumulators are in good shape?
Observing the dipstick levels. There are two notches on the dipstick. The lower one is when the engine is running, the upper one for when the system is off and fully depressurized. If your fluid levels are set correctly for when the car is shut off(the higher mark), and then you start the car and don't see the fluid level drop to at least the lower mark, then there is likely a blown accumulator(s). Each of the two main accumulators account for about 1/3 of the dipstick difference. The pulsation dampener and return accumulator are smaller and make up the last 1/3.
I performed this test. The engine off dipstick level was right at the full level which is interesting because the burp pissed out some fluid that I have not replaced.
The engine on dipstick level was below the full mark (engine on), but not significantly low. I noticed air bubbles in the fluid which is concerning. Here is a pic.
According to test one, this does not suggest a blown accumulator if I am reading things right.
RPM drop when cycling through the ride heights. The accumulators, when healthy, have enough capacity to lift the car from the normal level to the highest level without the pump having to work hard. If you press the ride height button quickly twice, and you hear a RPM drop during the raising process, then you may have a blown accumulator. The pump is having to step in and help lift the car.
After the car was warm, I could quickly cycle through height control without any pump noise or drop in RPM. Again, does not point to accumulator.
Visual inspection. If an accumulator has blown, it will be full of fluid, and you can reach a considerable distance into it with a wire or screwdriver. But if you are going to go through the work to pull the accumulators, I recommend just replacing them regardless of what you find, as a preventative maintenance investment. Accumulators cost about $150-200 each.
Haven't done this yet. As a novice, i do not want to start removing parts until I have further diagnosed the situation.
I drove the car a few miles today. Took it over some bumps and a few tight turns. The car performed normally. I now carry around a liter of CHF11S and some clean micro towels just in case. And always a cell phone and AAA account number.
Any help at this point is much appreciated. I looked at DAS simulator today and it looks like I can perform a rodeo on the car. I have read it stresses the ABC components and could cause failures. I suppose I should give it a try anyway.
Could someone explain to me how the fluid level in the accumulators change between engine on and engine off?
I am thinking if the fluid leaves the accumulator in the off position, I would see a full reservoir when the engine is off which is exactly what I see. Then, with the engine on, the accumulator fills with fluid and if the nitrogen is blown out of the accumulator, more than normal fluid would fill the accumulator. This would explain why I see proper fluid level with engine off and low fluid level with engine on.
Could someone explain to me how the fluid level in the accumulators change between engine on and engine off?
It is a fact that the volume of fluid within a functioning accumulator increases when the engine is started and diminishes when the engine is shut-off. It is intuitive to me that a blown accumulator with a damaged membrane will fill with fluid and never empty, since there is no internal nitrogen pressurizing a membrane to displace the fluid.
Last edited by bobterry99; 08-07-2016 at 11:28 PM.
It is a fact that the volume of fluid within a functioning accumulator increases when the engine is started and diminishes when the engine is shut-off. It is intuitive to me that a blown accumulator will fill with fluid and never empty, since there is no internal nitrogen pressurizing a membrane to displace the fluid.
One would then assume the fluid level on the dipstick would drop when the engine is off and when it is on.
07-13-2016, 12:01 PM
