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I need some advice. My 2008 SL550 only has 31K miles on the odometer (Yeah, I don't drive it enough!) In recent months it started to show some disturbing symptoms of trouble in the ABC system. At first, I noticed minor oil stains on the garage floor under the driver-side front end. Also, I could hear the ABC pump running for a few seconds after a cold start. Then all Hell broke loose on a short (3 miles each way) trip to the store.
As I parked in the store lot, the "Visit Workshop" warning came up on the dash. It was the first time I had seen it. On the return trip, the same warning came on in the first minutes, then it suddenly turned to the red "Stop Driving" warning about a mile from home. I drove the final mile, shut the car down and opened the hood. The serpentine belt had sprayed fluid so widely that I couldn't even determine where the leak originated. The ABC Fluid reservoir dipstick showed the fluid level below both marks, but not yet empty.
After raising the car and removing the underside panels, I began topping off the fluid and running the engine in short bursts. Eventually I was able to zero in on a leak under the ABC pulsation dampener. It was squirting out in a pretty strong stream while the engine was running.
My 2008 model has the 2007 ABC update, so the pulsation dampener is mounted directly on the ABC pump body (attached photo). Replacing the pulsation dampener is not a trivial operation, as it requires removing the belt and pulley and loosening the pump mounts and probably even more mucking around. ABC Fluid Leak Location
My question is: How likely is the immediate problem to be limited to replacing just the pulsation dampener? Am I about to start a process that involves a much larger repair?
I have been considering doing a coilover suspension conversion next year. Should I do it sooner?
Last edited by CPDay; 10-09-2018 at 07:09 AM.
Reason: Add image
First of all, whatever noise you hear after shutting down the engine was not the ABC pump. It is belt driven and will only run with the engine. Maybe you hear the SBC (Sensatoric brake) pump running? That is common and totally unrelated..
Now, are you certain the leak is coming from the pulsation dampener and not the hose that sits in front of it? The reason I ask is because my hose failed with a pinhole leak right there where your lower arrow crosses it. It sprayed directly onto the belt and the pump. It might have appeared to be coming from the pump or dampener, but it was the hose. And I have read of several others in the forum with the MY2007+ revisions experienced the exact same leak. Apparently, these hoses have a defect. Anyhow, if that's the case on yours, it's a fairly easy job. I think I paid just over $200 for the hose from an online dealer (one of the MBZ dealerships with an online parts store).
I would say you simply have a leak at the seal, which would be as easy as replacing the seals to the dampener. Since you did not drive a long distance with the pump 'dry' it is likely there is no other damage to the pump or system.
If it were me, I would remove and replace the dampener with new seals, and then test the system for pressure using the SDS or similar device that can read the pressure.
If the pressure is normal, everything should be fine. If low, you likely need a pump too.
The dampener can have an age limit (~10 years) rather than mileage limit, so it would be good to replace it now for about $100.
Personally, I would not go with the coil over system, as it is not well sorted for this car, and you would likely loose value and drive-ability. Others will have their own opinion.
Keep us posted on the outcome.
First of all, whatever noise you hear after shutting down the engine was not the ABC pump. It is belt driven and will only run with the engine. Maybe you hear the SBC (Sensatoric brake) pump running? That is common and totally unrelated..
Now, are you certain the leak is coming from the pulsation dampener and not the hose that sits in front of it? The reason I ask is because my hose failed with a pinhole leak right there where your lower arrow crosses it. It sprayed directly onto the belt and the pump. It might have appeared to be coming from the pump or dampener, but it was the hose. And I have read of several others in the forum with the MY2007+ revisions experienced the exact same leak. Apparently, these hoses have a defect. Anyhow, if that's the case on yours, it's a fairly easy job. I think I paid just over $200 for the hose from an online dealer (one of the MBZ dealerships with an online parts store).
Thanks for your quick reply! I should have been clearer in my description of the noise. It was occuring after an initial start, while the engine was running. It lasted just a few seconds and was a "tap-tap-tap" sound. I thought that it was the ABC system leveling the car. It was a new sound in the months before the big fail. I thought that it could perhaps be caused by the ABC pump pulses NOT being properly dampened.
Like you, I also suspected a leaking hose in the serpentine belt area, but I was finally able to actually see that it was somewhere near the base of the dampener. The fluid is leaking so fast that I can't observe it for more than a few seconds of running the engine. I'd like to get a picture of the leak in progress. Perhaps I can use my inspection camera. I also have a Star Diagnostic system which should help with this at some point.
I would say you simply have a leak at the seal, which would be as easy as replacing the seals to the dampener. Since you did not drive a long distance with the pump 'dry' it is likely there is no other damage to the pump or system.
If it were me, I would remove and replace the dampener with new seals, and then test the system for pressure using the SDS or similar device that can read the pressure.
If the pressure is normal, everything should be fine. If low, you likely need a pump too.
That sounds right. A faulty seal would certainly produce this kind of leak. It looks like I'll be following the advice of replacing the pulsation dampener and seals.
Do you have a good source for the replacement dampener? I think the dealer wants about $400 for it. There seems to be a lot of confusion on the Web re part numbers. (A 000 466 03 10 ?) I guess I'll get the right number when I pull the old one.
UPDATE 10/9/2018: I was just removing the serpentine belt when my knuckles accidentally brushed against the pulsation dampener and it turned! In fact, it was so loose that I could spin it with just my fingers- no wrench needed. I guess that pretty clearly points to the pulsation dampener seal being shot.
I still can't back the pulsation dampener all the way out without loosening the ABC pump mount(s). But now I know what I'll be doing. Thank you, kbob999!
UPDATE 10/17/2018: I bought a set of e-torx sockets from Amazon and was finally able to remove the ABC pump mount bolts and then move the pump just enough to get the dampener out. The o-ring on the dampener mount was in shreds. I probed the dampener and the diaphragm seems to be intact. I will replace it regardless. Now I need to find a new dampener and seal...
UPDATE 10/19/2018: My local dealer had a difficult time identifying the pulsation dampener. It turns out that it was labelled a "power steering damper" in his inventory database (Part# A 000 466 03 10). That was certainly possible, given that these later R230's had the tandem pump design. It turns out that our metro NY MB warehouse has 40 in stock! I expect it tomorrow. I certainly hope it arrives with the hydraulic seal ring.
Last edited by CPDay; 10-19-2018 at 01:07 PM.
Reason: Update info
I picked up the new Pulsation Dampener/Damper this morning, took it home, and spun it down in place on the ABC pump. Then I stopped and thought "What torque should I tighten it to?" This could be a crucial question, as the entire leak may have been caused by a damaged o-ring. Damaged, perhaps, by an over-tightened damper? Time for more research...
Of course! I know every torque rating of every bolt on the car! (and if you believe that, I have this bridge for sale... ) Seriously, I just popped into WIS and checked it out. And I already had been on that page because I need to replace mine, too.
I should conclude this thread with a simple summary: My 2008 SL550 suffered a serious ABC failure on the road. The fluid leaked rapidly and evidence pointed to a serious leak in the hydraulic lines or other costly components. In the end, it turned out to be the failure of a single o-ring under the ABC pulsation dampener (damper). The dampener itself was not damaged, but I replaced it anyway with the new o-ring. Everything is now good.
Lesson: Don't assume that an ABC problem will cost a small fortune. The o-ring cost less than $1 and I replaced it myself with support from this forum.
I should conclude this thread with a simple summary: My 2008 SL550 suffered a serious ABC failure on the road. The fluid leaked rapidly and evidence pointed to a serious leak in the hydraulic lines or other costly components. In the end, it turned out to be the failure of a single o-ring under the ABC pulsation dampener (damper). The dampener itself was not damaged, but I replaced it anyway with the new o-ring. Everything is now good.
Lesson: Don't assume that an ABC problem will cost a small fortune. The o-ring cost less than $1 and I replaced it myself with support from this forum.
was the o ring an OEM part? Do you remember the part number or size of the o ring?
As I had gone through the considerable effort of removing the old pulsation dampener, and knowing that they have a limited lifetime, I replaced it with a new Mercedes factory-refurbished dampener. The new dampener came with the O-ring already installed. I didn’t measure it, but I probably should have, just for the record. I know that large sets of variously-sized, hydraulic service-quality O-rings are readily available on Amazon and elsewhere.
What year is your car? Later models have dampener on the pump.
Earlier models are at rear of the left front fender well. Remove fender liner to access dampener. I think this early one is easier to replace, but that is my opinion.
Thank for your answers. I removed the pulley from the pump, removed the upper front screw, loosened the lower front screw, loosened the screw from the engine block bracket and pulled the pump slightly to the side to make enough room for the pulsation damper to be removed. Installed in reverse order. I little bit tricky to loose the bracket screw, but did it.
Thanks again.
Last edited by Cristian Kruger; 08-12-2023 at 04:23 AM.
10-08-2018, 07:16 PM
ABC Pulsation Dampener Leaking?
) Seriously, I just popped into WIS and checked it out. And I already had been on that page because I need to replace mine, too.
