Let me start off by saying, I'm totally new to this generation of Mercedes. I am only familiar with 2012 and up Biturbos with dynamic ride, none of this NA ABC air ride. Forgive my ignorance, I'm sure this has been brought up a million times, just couldn't find one with my exact scenario.

Bought my SL500 R230 from a friend of mine who was looking to get rid of it after the issues. The car had been at a pretty reputable mercedes indy shop who pretty much gave up on it. From what are in my records and what I've been told, a hydraulic leak was found. Indy shop replaced with an "aftermarket" $600 pump. Within 3 miles, "ABC Light came on, pump making 'weird' noise like it was not holding prime". Apparently a 2nd bad pump. Shop was unable to find another pump, which is when I purchased the car for $1,000. 15,000 miles before this, ABC valve block was replaced. 1,000 miles later, connector on valve block started leaking. Connector was tightened, rodeo test was done. 3,000 miles later, valve body had to be removed, cleaned, and refitment of all connectors. 10,000 miles later, ABC hydraulic line blew and had to be replaced.

I immediately scanned the ABC module, (I don't have a star tool or any fancy scan tool, but I do have a pretty expensive bidirectional tool) came up with codes:
C1353-001 - Fault in component Y86/1 Suction Restrictor Valve (Logged on to my mercedes repair database, found the diagram, doesn't appear that it is sold separately)
C1525-064 - System Pressure too low
C1526-016 - Malfunction in pressure supply

The suction restrictor code has since gone away and is not coming back.

The interesting thing is, the car does not sag at all. It feels very comfortably and suspension is like a cloud. I would imagine if the air ride is out, it would get stiff and sag? I did notice the ABC sport button has no effect at all.

Fast forward to today, (yes I have been driving the car, the pumps already blown, whats the harm?) I appear to have blown a hydraulic hose in the driver side front wheel well. Haven't gotten under it to check it out yet.

My question is, given the notorious unreliability of the ABC in this generation of Mercedes, and given the car has already had this much work done to the system, am I better off getting rid of the ABC suspension and converting to coil springs? I read that I can swap the power steering pump off a CLK500 from the same year and delete the ABC pump that way.

 

The pro and anti coil over and must have and don't need sway bar guys will be here soon to give advice, I will refrain.

As far as the second pump, I doubt that it was faulty. When you introduce air into the system the pumps like to lose prime. Sometimes they won't pressure up and sometimes they pressure up initially, but still lose prime when the air works its way through the system. If you are considering keeping ABC, first find out what is leaking. It might be the pressure regulating valve and that might be your only issue. It seems odd that a system that won't build pressure would blow a hose, so I think something else is going on. If you decide to fix that, the next step is to apply pressure to the ABC reservoir and see if you can get the pump primed. A scanner that reads actual pressure would be important for that process (yours might be capable).

The ride you were getting is probably a limp mode of ABC. When low pressure is detected, the valves are locked and you have no active control, it is just the soft spring and internal damping in the strut that controls the ride.

 

My question is, given the notorious unreliability of the ABC in this generation of Mercedes...
Hmm. I'd be suspicious of that indy mechanic, they sound a bit unreliable. Sounds like they didn't prime the pump which is essential after you change it. ABC is pretty old now and newer techs may not know much about it. The ABC can be surprisingly easy and low cost to maintain once you get your head around it all, be cautious about ripping it out. I'd persist with it. Lots of ABC experts on this board.

Fix the leak and see how you go. If the ABC goes into limp you'll get the 'tuna boat' ride, pitching back forth and bouncing around like a pogo stick. Functioning ABC is as smooth as butter.

The pro and anti coil over and must have and don't need sway bar guys will be here soon to give advice, I will refrain.
Good to stay out of that discourse, there's a bit of zealotry around the subject. Think about the most practical and cost effective solution for you - it doesn't sound like there's much wrong with it now.

 

I'm pretty much with you there. That shop is extremely high on prices, and I don't think that they perform half the things you're getting charged for. I would've never taken it to them if I had owned the car. I'm going to get under it hopefully tonight and see if I can figure out what the leak is. I will say, I've been driving the car for a week with the red ABC and the codes I mentioned in my original post. The leak only happened this afternoon and there are no new trouble codes. I would prefer to keep ABC, as it seems really comfortable and nice, but I don't want to spend more than the car's worth in maintaining it.

From what I read, the ABC pump is a tandem pump, so the power steering and ABC are built into one pump? I used to work at oreillys, and we sell a power steering pump for it for about $500 ($350 discounted). The images look exactly like what I'm seeing for ABC pump, so would this be the same thing?

 

Unfortunately, my scanner is not capable of doing ABC live data. But I work in the shop at a lexus dealership, and we've got a snapon scanner that will do rodeo and live data. Will give that a shot at some point.

 

City man, $1000 for a SL...great deal....! When you find another of these deal...please let me know!

As for the ABC, yes, it is a great feature.....but as time goes by components wear out and then becomes a maintenance headache. Rubber components are the first to go!

When I bought mine the ABC had numerous issues, so I took the easy route and replaced the system with coilovers and a front sway bar. But...if you can keep up with the ABC ...it is great...on the other hand, if you want a reliable suspension system...coilovers is the way to go. Regarding the pump, I bypassed the tandem pump output line back to the reservoir and no issues..!

 

You may not have blown a hose - stray ABC fluid at the left front is often caused by the fluid overflowing out of the reservoir. This is usually caused by a diaphragm in one of the accumulators rupturing, allowing the accumulator's gas charge to escape into the hydraulic system. Basically, a big air bubble gets forced into the system which pushes pentosin (ABC fluid) back into the reservoir, causing the overflow.

I'd check the fluid level to make sure it's topped off, then look for any active leaking. If you don't find any, cycle the ride height through all levels a few times, then recheck fluid level, then repeat this process 5 or 6 times. If it appears the system is leak-free, look at replacing all accumulators and pulsation dampers. There's probably only one blown, but they all have similar age/wear and tear on them so if one is gone the others are likely to soon follow. It can also be difficult to test the accumulators to see which one is blown - there is nothing in vehicle's electronic diagnostics that will tell you specifically that an accumulator is blown, much less which one specifically.

What's the car's mileage? If it's anything over 60-70K miles I'd consider all accumulators/pulsation dampers to be at the end of their life anyway, and it's best to replace these before they rupture. When they blow, it's possible for pieces of the internal rubber diaphragm to tear off and get pushed out into the hydraulic system, causing clogged lines/valves etc. which can be a bit of a nightmare to track down. I always advise to consider ABC accumulators/pulsation dampers in the same way you would a timing belt - you really want to replace before failure, because things can get very complicated if you wait until they go.

As far as converting to coilovers - definitely a personal choice. Some folks feel that ABC is an essential piece of the R230 and should never be removed, but the fact is that maintaining it can easily approach a large percentage of the market value of the car. ABC is a hill you choose and may in fact die on (at least financially). Ongoing reliability and the fact that this system can fail in a manner that makes the car both undrivable and very difficult to tow are considerations as well. You can search for posts by me for some deeper analysis of this, and they'll be in threads with lots of other opinions. Sway bars are also included in those discussions - some say they're needed, some say they're not.

There's a good choice of quality coilover kits out there. If you're looking at these, the main advice I'd give is that you want to get a set that is -fully- adjustable. You want to be able to adjust damping stiffness, ride height, and spring preload. A couple of the most popular kits out there are completely non-adjustable; the only reason these kits are popular is because they were the first R230 coilover kits available, and were the only kits available for a few years. Some of the people who installed these kits have been unsatisfied with ride quality and/or ride height, and there's not a lot they could do about it.

I went with VVK coilovers and sway bars and I'm very happy with my decision.

 

Ditch it if yiu can’t perform repairs yourself. There’s a reason your friend got rid of it.

 

Sadly, this is true. I could work on mine and still got rid of it. IF you have the pump or some other bladder come apart, the system is generally totaled. I will be VERY expensive to replace/fixed.

 

You are 100% right Bruce...you may love the ABC...but if at one point gets too expensive or difficult to DYI maintenance there are a couple of choices: Sell it as is or do the coilovers! It is like a wife...you may love her, but if at one point she becomes unsustainable....divorce her!

 

Another point to consider on coil overs is the cost of strut replacement if ever fails....!

 

Didn't realize I got this many replies. First off, my friend is an older retired military veteran who has paid this indy shop $25,000 over the last 6 years in maintenance. He was done with it, and I don't blame him. He basically gave me the car for free.

I got it up on the lift today at my dealership, unfortunately the driver front air strut has totally blown. Fluid is everywhere under that side of the vehicle and inside of the strut. Leaked out all of the hydraulic fluid. I had a certified master tech take a look as well and he agreed within a minute of looking at it.

Given the fact that a new single air strut is almost $1,000, and I will still be tracing a pump issue, and whatever issues follow that, I think my best financial decision is going to be a coilover conversion kit.

My plan right now is to order a power steering pump for a '04 CLK500. That should be a bolt on replacement, and will delete the tandem ABC pump, correct?
In the meantime, until I can come up with a solid parts list and plan of attack, I'm going to continue to drive the car like it is. What's the worst that could happen, I blow the valve blocks that I'm planning to delete anyway?

 

The worst that can happen is the system becoming completely depressurized allowing the struts to completely compress. The car will sit so low that turning the steering wheel can cause the front tires to damage the fenders, making the car undrivable; also so low that it's a problem to get the car on a flatbed tow truck without damaging the front bumper and undercarriage.

This is another reason for coilovers.

 

Definitely doing the coilovers when I can afford them.
But that's the thing thats stumped me this entire time, according to the ABC fault codes, the system has had no pressure the entire week that I've been driving it. Even now, with the front strut blown and no hydraulic fluid in the system, the car still does not sag one bit. Does it have bump stops or is it just riding on the spring at this point?

 

There are many options on coil overs......even Mercedes has a coil over system that will fit the SL-500 since the SL-350 has them. You could buy Bilstein struts, Lesforos coils, and the Mercedes top mounts. at a lower price than the Fancy kits with strut dampening adjustment, height adjustment, etc. But,.......... it is a personal preference and a budgetary issue. In my case my SL is a weekend vehicle and want to keep the cost of ownership as low as possible so the wife doesn't *****.!

Many argue that the SL-350 which has a 6 cylinder engine, the front springs will not support the V-8 weight and will sit lower...the Bilsteins has grooves in the body that allow to raise the suspension in a 2" range. My SL-500 has these components and sits perfectly level with 27" from the ground to the top of all fenders..! An additional advantage of using stock components is, if any of these Bilsteins fail, you will be out of $100 instead of $300!

 

I was going to ask if there are factory options for springs that would be a drop in replacement. So I can get coil springs from a sl350 and they will drop in? Did you buy a module to fix the ABC light?

 

Sl350 springs won’t have the same spring rate as the 500. Get coilovers and put it at the height you need.
You need the xentry or similar to code out the white ABC warning light.

 

CDK, no disagreement if you use the stock SL-350 struts which have a fixed point of support on the strut body. It will sit lower indeed, but if you have the ability to move or elevate that suspension point you will have the same height as a "right" spring. I can argue that the rate may be equal both the compression height is different in both versions.
Typically these springs have a rate around 250 lbs/in. so, Since the point of support for the spring is midway between the fulcrum and the tire point of pressure, and the car weights 4000 lbs, every tire will be supporting 1000 lbs, so my spring is compressed 8 in from the free state to produce 2000 lbs at the lower joint. Now lets say the SL-350 is 200 lbs lower in the front end..! then the spring will be compressed 8-1/2 inches which will translate at 1 in at the wheel. In other words, if I have the capability to raise the point of support within the strut body by 1/2", I will be at the same height! And that is fully proven in my Car..! See how level is the suspension!
But as we all know, it is a matter of personal preferences!