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Hi all,
I own a 2013 R231 SL 550 4.6 liter with 70,000km or 43,500 miles.
The problem started 2 months ago.
This seems to be a very difficult problem to ID because a dozen different mechanics including
A top Mercedes one with 40 years experience with Mercedes cannot positively ID the problem because if he’s wrong it’s a $ 3700 CDN part (Germany only) plus labor to replace ABC pump.
Here is what is happening.
The is a loud whining and grinding intermittent sound felt in the steering wheel coming from inside the left front fender (Location of the ABC pump) The sound starts about 20 seconds after you start the car from a cold start and does not seem to be affected by the car’s speed.The grinding part of this sound is getting worse each day.
What I find strange is that this sound follows the engine RPM’s. I was assured by this top mechanic that it has nothing to do with the transmission. Not the fan, it was disconnected and AC on or off has no effect. There is no oil leak or error messages on dash or with Mercedes OBD2 scanners.
The car was on a lift for ½ hour running on idle. The inner fender was removed revealing the ABC pump and we can hear a fast clicking type sound coming from the pump area and you can follow the sound with a stethoscope by following the steel tubing located from the ABC pump to the front center of the engine near the Power steering pump but working hard the steering has no effect on the sound.
Could this be a pulsating damper problem, and would the noise follow RPM’s?
To make it easy to pin down, the sound is not affected by being in a D.N Reverse positions, working the brakes, moving the ABC controls on the car to raise and lower the car and go to sport and comfort positions.
Has anyone experienced this problem, I would appreciate your experience.
Buzzing or grinding sound from the ABC, vibration that telegraphs up the steering column, and sound that varies with engine RPM are all classic symptoms of a bad or failing pulsation damper.
Just out of curiosity, does the noise decrease or even go away above about 2,000–2,500 RPM? Even if it doesn't, it could still be the pulsation damper, but if it does decrease, that would be another clue in favor of the damper and not the pump.
The problem does sound like an ABC pulsation damper but your description is a head scratcher.
- "power steering pump" near "front center of engine" - AFAIK all R231s have electric steering assist, so no power steering pump.
- "left front fender location of ABC pump" - again AFAIK you're describing the previous R230 model and in the R231 the ABC pump is in fact the one that's at the front center of the engine.
Could you post up some photographs so we can be sure?
BTW, if I'm right, I would then seriously question the competence of your mechanic, 40 years experience or not.
BTW, if I'm right, I would then seriously question the competence of your mechanic, 40 years experience or not.
I wasn't going to say that, but it probably needed to be said. :-) In defense of said mechanic, it probably depends on where a person lives. In a smaller town or a rural area, it's probably possible to work on Mercedes cars for 40 years and have seen only a handful of SLs. (Although the basics of ABC are common across a few of the platforms.)
Buzzing or grinding sound from the ABC, vibration that telegraphs up the steering column, and sound that varies with engine RPM are all classic symptoms of a bad or failing pulsation damper.
I agree, this is a somewhat common repair for noisey ABC systems on this model and engine. Replace this first.
(Although the basics of ABC are common across a few of the platforms.)
Yeah, maybe I was too harsh, for this reason though...I believe MB have moved the location of the ABC pump around so the mechanic(s) (since he said several had seen the car) may not have seen the implementation in an R231. I know for sure in my SL63 M157 engine the pump is smack dab on top of the engine right in the center, and I think the M278 in the SL550 is identical.
Be sure the ABC fluid is a light lime green in color and has not turned a light brown. If the pulsation dampener needs to be changed out the fluid will be changed also.
As I said, the winning and whirling sound is intermittent and is on for about 10 seconds then stops for about the same period of time. As I increase the RPM’s it gets louder and converts to a screeching metal to metal sound at 2000 rpms like a failing bearing. The sound is at its best from 1000 to 2000 rpms.
I made a fast increase in rpms to 3500 rpms then made a quick release it and the screeching sound was so loud at that peak that I thought something broke.The vibration transfer to the steering wheel is very present.Strangely, parked and on idle at about 700 rpms the sound is constant and is back to a whirling sound.
As soon as I get it in drive and start to move the sound stops then returns at 1000 rpm+ then its intermittent.
A lot of qualified mechanics road tested the car and they never heard that type of sound and cannot identify it.
I received other comments saying there is no power steering pump, it’s electric.The car is a 2013 R231 SL550 with an electromechanical power rack and pinion steering. I flushed the power steering pump and replaced the 3.25 liters of fluid.
Hi ram_g, thanks for your reply,
No, I think I will keep this 40 years of experience mechanic.
To give you a bit of background, the car is a 2013 R231 SL550 with an electromechanical power rack and pinion steering delivered in July 2012.
I had the power steering pump flushed thinking it was the pump and replaced the 3.25 liters of fluid.
I do not think that there is a difference a Canadian and American version.
The ABC pump is inside the left front (Driver side) wheel well and is quite large with many tubes going in and out. I can't give you a picture without opening it again.
I honestly think you are referring to the front valve block when you say that the ABC pump is located in the wheel well. If it is in the wheel well, how does it get its motive force? The ABC pump is driven off the engine serpentine belt - does that go to the wheel well also?
This is the ABC pump in my 2013 SL63 with the M157 engine. The SL550s have the M278 engine that is a smaller version of the M157 and visually very similar. I am pretty sure the ABC pump is in the same location and is probably the same pump.
Again, thanks ram_p,
My mistake. We spent an hour trying to pinpoint the source with the car on the lift engine running and wheel well opened.
Using a stethoscope, the sound is present from the ABC pump (steel tube on your picture) following the tubing back to the valve block. It's louder from the valve block.
Can a valve block fit the symptoms and does it have removable parts to replace. Cant say witch end of the tubing is defective but because of the vibrations felt in the steering wheel I would say its from the wheel well valve block.
What do you think ?
Regards
The actual pump is below the steel tube - that is the high pressure output that leads (as you correctly say) to the valve block.
I doubt that the valve block itself can be the cause of noise/vibration. There are three dampers/accumulators in the system that smooth out hydraulic pulses and reduce noise - one at each valve block, and one at at the pump. The one at the pump is the black bulbous looking thing to the rear of the pump nestled between the air tubes (towards the top, in my picture). These dampers/accumulators fail with time and should be treated as maintenance parts.
If the damper/accumulator on a valve block fails, the typical symptom is a momentary loss of pressure as the ABC system works. The failure of the pump damper typically causes the noise that you describe, albeit a bit less loud than your description. It is not difficult for a mechanic to replace the damper. I had a very similar noise in my own car and it was fixed by replacement of that damper, cost to me at a local independent mechanic - USD 380.
It is possible that in your case it is not the damper alone, but the entire pump that needs replacing. In the US, Mercedes-remanufactured ABC pumps are ~$1000 and are readily available, no need for special order from Germany.
Yes, IT DOES FIT the 2013+ SL550/SL63 and it DOES NOT HELP that it is called a "power steering pump insulator" because there is no power steering pump in the R231. Sorry but I remain firm on that last point. Not sure what it was that you had flushed, but it wasn't the power steering pump.
Thank you for your help and especially giving me the part numbers and your clear explanations.
I can’t argue with you regarding the power steering pump, I presumed it was a pump as many sites call it a pump and it’s described as such on different parts sites.
You are suggesting 2 different parts. With the symptoms described are you leaning towards one in particular. Also, when replacing the pump, does it come with the dampers or do all 3 have to be replaced?
Mercedes parts catalog listings for the R231 SL are not great and sometimes downright mislabeled - why, I have no idea. Another example is that they do not list the ABC filter as a separate replaceable part whereas many posters have stated that the filter is the same as in other ABC equipped MBs.
Unfortunately it is hard to say whether your noise is just the pump damper or the whole pump itself. Personally I would start with the damper as it is much cheaper, but if that does not work, you will be incurring more expense to go to the pump replacement. My understanding is that the replacement pumps come with dampers. Perhaps you could check with your shop if they will return the damper and install the pump without incurring additional parts cost for the unused damper, if the problem doesn't go away with the damper alone.
Edit > BTW, please post whatever is your outcome, so we can add to the collective body of knowledge.
Follow up R231 2013 SL550 , ABC pump or damper or both
Hello again all, remember my post “Problem that no one can identify”
Well after reading different comments and agreeing that the problem sure sounds like the pulsation damper, I had it replaced by an independent Mercedes specialist shop that I trust.
I am including some pictures with this post that can help Identify the problem. This is for a R231 2013 SL 550.
It’s difficult to pinpoint the sound because it starts at the output of the pump located front and center on the engine, travels down the pressure tubing inside the left front mudguard down to the valve block and finally to the Pulsation Damper.
It’s now my experience that the sound can start from either end making it hard to pinpoint is it the Damper or the pump. I was hopping for the Damper.
I don’t think that this is a DYI project unless you have specialized tools, look at the photos.
The first thing, my mechanic used was his High Teck diagnostic tablet to reduce the high hydraulic pressure down to zero without having to disconnect the hydraulic lines.
The first picture shows you the location of the Pulsation damper on a R231. Front left (Driver side) hidden behind the valve block and complicated to get to.
A special thanks to Mercedes for putting it in such a place that you must disconnect all high-pressure lines to get to it. The valve block and Damper are on rubber mounts, so it was easier to pull it out than loose time fiddling with it.
Once replaced, the mechanic used his tablet to increase the pressure back to normal, equalized the pressure on all for corners and told it to purge itself.
It was quite a sight to see the car jumping up and down on all 4 corners let to right, front to rear by itself for a few minutes to get the ABC system back to normal.
This whole operation took about 1 ½ hours. Here in Canada, the EOM damper costs $ 375 and 1½ hours of labor at $70/hour. Its close to a $500 repair. It took ½ hour just to get to the Damper.
BUT NOW………..
The major screeching and grinding are almost gone but that darn intermittent writing hum vibrating into the steering column is still there. It’s much quieter but still there. Starts on idle 750 rpm, stops once I start to move up to 1000 rpm than stops and comes back loudest at 2000 rpm. The sound follows the RPM”s.
Previously, the Mercedes dealership had quoted a price of $3700 + labor to replace the pump. My research showed that in that price they were replacing the valve block and damper.
Has anyone ever heard of a defective valve block (Excluding the Damper) Are there any parts that can produce the sound I described? That valve block OEM is $1600 cdn and probably not required.
I put my stethoscope a stethoscope on the steel tubing just off the pump. I hear la loud clicking sound.
Is this normal?
Thanks to all posted their comments and best regards.
Hello, all. I have found this thread on ABC issues very useful. I have owned a CPO 2014 SL550 for 5 years. I bought the car off a 3 yr lease and it had 17k miles at the time.
At 20k miles the ABC started growling from the left front when going over bumps. Under warranty, the dealer replaced the front pressure accumulator and this resolved the problem.
Then last Oct 2022 (50k miles) I noticed an intermittent squeaking and growling and vibrations which were noticeable in steering, brake and seat. Dealer diagnosed this as 'valve element malfunction in front valve block.' After a $61 valve insert and a $500 bill for labor, The squeak and growl seems better, but the intermittent vibration noticeable in steering are still present. Based on this thread, I believe the problem to be the Steering Pump Insulator. I will let you know once the problem is addressed in a couple of weeks.
The ABC adds a whole new level of complexity, but when it works, the ride could not be better! So far I think its worth the headaches, but if the struts need replacing?!?
I had a vibration issue, although a bit different from yours as the vibration was not only on startup but also while idling. It was the ABC pulsation dampener.
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ABC issues
