When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I am about to tackle the tandem pump pulsation damper on my 2009 SL550. Anyone who has done this knows the damper is partially blocked by the dual o/h cam housing.
For this reason, the pump will have to be loosened slightly, including the rear bolt, so that the pump can be "tipped" forward slightly to clear the damper for removal and new unit install.
Question is: from underneath, with bottom panel(s) removed, is there a fairly clear view of the back bolt to access and loosen it? I'm sure it is very tight, but can I see past other things to find it?
Does anyone have any pictures or video from below?
Finally, is removing the front cover from the cam housing a possibility, as an alternative to loosening and tilting the pump?
That guy makes it seem pretty easy. You could remove the front head cover, but I don't think that would help much, and it's a bit of a pain having to remove the oil filter housing. Also, the front head cover has to be re-sealed with high-temp RTV, which puts the car out of commission for 24 hours while that cures.
Does ANYONE have any pictures or video from underneath showing access to the back bolt to the block for the tandem pump...that needs to be loosened to move the pump to clear the damper for replacement?
I am about to undertake the same operation (replacing pulsation dampener) on my 2008 R230. I posted my story of ABC failure yesterday in this forum (see ABC Pulsation Dampener Leaking?).
I have many questions: Did your dampener start leaking ABC fluid (like mine did) to indicate the need to replace it? How did you finally get the dampener replaced? Did you try removing the front cover from the cam housing? Where did you buy the new dampener ($$ dealer)? Did you find any additional or associated ABC problems? Any newer information will be greatly appreciated!
Thanks in advance, CPDay
Last edited by CPDay; 10-09-2018 at 10:43 AM.
Reason: Typos
I replied in your other thread, too. This may not be the dampener leaking. Check the high pressure hose that runs in front of the pump for a pinhole leak.
Regardless, this is a timely post! On my way back from Nashville last week, about 30 miles into the 200 mile drive, I began to hear a noise. At first I thought it was a loud exhaust from a vehicle ahead of me, but once I passed the "herd", it was still there. I found that it changed pitch when I downshifted. It was sort of a whining/groaning noise. I stopped at a rest area and could hear it just a bit from outside the car, but it was more noticeable inside. Like I said, it was a whine, sort of like what a bad torque converter or transmission fluid pump might make. I saw no signs of leaks, so I continued on home. When I got home, I raised the hood and checked, but it was hard to hear unless the engine was around 2500rpm. Then, it did sound like it was coming from the left side of the engine in the area of the ABC pump.
The next day, I got out to investigate further, but it was all quiet. I even drove around a bit and did not hear it. I recall another forum member mention the same thing, that the noise was only there after everything was well warmed and only at higher RPMs. I'll look into it more when I have time, but it sure seems like the pulsation dampener is the likely culprit.
I replied in your other thread, too. This may not be the dampener leaking. Check the high pressure hose that runs in front of the pump for a pinhole leak.
Thank you. A good suggestion, but first I am pursuing another one: A failed seal on the pulsation dampener (see: ABC Pulsation Dampener Leaking? ) We will see...
You are certainly right about the timeliness of these posts. ABC systems seem to be dropping like flies!
Last edited by CPDay; 10-09-2018 at 03:03 PM.
Reason: Added more info
ABC issues are really not any more prevalent on the forum than normal. It is a big source of maintenance, and people always come here looking for help with problems.
I guess we will both get to see how difficult this job will be. I really haven't 100% determined that it's my problem, but all things seem to point to it. Driving a few miles around town the last few days, I've not heard the loud whining, but I feel some extra vibration. I think I'm just going to replace it anyhow since the part is so cheap (under $150).
I removed my Pulsation Damper/Dampener without needing to loosen anything on the back (i.e, the side opposite of the pulley) of the ABC pump. I removed the top front mount bolt and loosened the lower front mount bolt. That alone let me tilt the unit just enough to remove the Pulsation Damper. It is still not clear to me where the proverbial "rear mount" may be. There is a third e-torx bolt head on the rear, but it appears to be holding the pump together rather than being a mount. I could certainly be wrong about that. It is VERY hard to see or photograph in that area. I may try again to get a clear image.
Mercedes' documentation of the 2007-2009 R230 ABC system is not very helpful.
A few weeks ago on my way back from Nashville, I began to hear an odd noise from the car. I was running about 90mph and it sounded like the whine you'd expect to hear from the differential in a big dump truck, but there was no dump truck nearby. After varying my speed and engine RPM, I realized it was coming from my car. I made a rest stop and could hear it coming from the engine. It was a sort of a whining/whirring noise, and I could feel some vibration in the steering wheel and pedals. These are pretty much tell-tale symptoms of a failing pulsation dampener. Further testing confirmed it. It won't make any noise until the fluid heats up. A single short drive of 5-10 miles with RPMs kept low would not create any noise, but the moment I revved beyond about 3,000RPM, I'd begin to hear and feel it. Or, after driving a bit and then stopping, I'd then hear the noise on the next drive. My theory is that there is a pinhole in the diaphragm and cold oil is too thick to enter it, but once it heats up, the oil thins and the pinhole expands, and it fills with oil and stops working.
Since my car has the MY2007+ ABC system, the pulsation dampener is mounted directly to the pump. WIS states that the pump must be completely removed for replacement. Part of this is for access, because the dampener is wedged in under the head cover, but also because the dampener is only to be removed with the pump upside down to prevent any contaminates entering the pump. I decided to take my chances and just clean everything thoroughly and remove the dampener after detaching the pump from the engine and sliding it forward. I took one photo (below) of the pump moved forward with easy access to the dampener.
To do this, I had to remove the serpentine belt, the pulley on the pump (to access one of the bolts) and the three bolts holding the pump to the engine. I also unbolted the pressure hose from its bracket to make access easier. The pump was easy to move forward enough for the pulsation damper the be accessed.
Here are the steps I took:
1. Lifted the front end and removed front left wheel (just for easier access for crawling under the car) and the lower engine paneling.
2. Released the belt tensioner from underneath the car and locked it in place with a small screwdriver.
3. Removed the bolt holding the pump bracket to the engine block. I decided to remove the bracket form the block rather then bracket from the pump as access was easier.
4. Back up top, I removed the serpentine belt from the ABC pump and AC compressor.
5. Disconnected the wiring harness from the ABC pump and move it out of the way.
5. Removed the top bolt holding the pump to the engine (actually it bolts onto the timing chain cover).
6. Discovered that even with some of my low-profile tools, I could not get to the lower front bolt without removing the pump pulley.
7. Removed the three bolts holding the pulley to the pump. Note that this would have been easier with the serpentine belt in place to hold the pulley, so do that first!
8. With the pump loose, I could slide it forward just enough so the pulsation dampener was clearly accessible (see photo below).
9. THOROUGHLY cleaned the area on top of the pump and around the dampener. I first hosed it down with a can of electrical contact cleaner. I figured that would be better than engine degreaser as it dries quickly. I used a microfiber cloth wrapped around the dampener and "buffed" it.
10. I replaced the dampener and put everything back together.
11. I found it easier to first install the top front pump bolt without the hose bracket to hold it in place. Then, i was able to get the lower bolt and bracket started, the rear bolt started, and then torque everything down.
12. I was able to hold the pulley with my hand when torquing its bolts.
The torque for the pulley bolts is 30Nm, the pump-to-engine bolts are 20Nm. The pulsation dampener is 45Nm.
bobterry99 (01-25-2021),CPDay (10-27-2018),GoFastr (10-26-2018),Leej (10-31-2019),MarkCan (10-26-2019),mb_texas (06-16-2023) and 1 others liked this post. (Show less...)
I recently replaced my 2008 SL550 pulsation damper by removing the top front mount bolt and then just loosening the lower bolt. Removing both front bolts on the ABC pump looks like it gave you much clearer access to the damper, important to keeping ABC fluid uncontaminated. I would use your technique next time.
BTW, my damper was not damaged. Only the o-ring was bad and leaking profusely. I replaced the whole 10-year-old damper anyway. The new damper came with an o-ring. Am i correct in understanding that there is ONLY the single o-ring, and not the o-ring PLUS some sort of hydraulic seal? I read several references to hydraulic seals (i.e, plural) on the damper mount. I never saw evidence of a second seal.
Last edited by CPDay; 06-29-2019 at 07:37 PM.
Reason: Fixed a typo.
I replaced my pulsation damper about 2 years ago because of the groaning/whinning noise and it solved the problem. I'm starting to hear that noise again. How can I test/confirm that the damper is bad?
On mine, it would not get noisy until either the hydraulic fluid was well warmed or I ran the engine at high (4000+) RPMs. It could drive for quite a while on cold fluid and get no noise. Also, I'd feel the vibration in the steering wheel and pedals.
Thanks for sharing this excellent write-up. I am in the middle of the job and cannot get the original dampener off. 17MM on bolt head on globe, right? Wont' budge. Ideas? Have used Craftsman max access a lot thanks for suggestion on these tools. Thank you
Thanks for sharing this excellent write-up. I am in the middle of the job and cannot get the original dampener off. 17MM on bolt head on globe, right? Wont' budge. Ideas? Have used Craftsman max access a lot thanks for suggestion on these tools. Thank you
I was prepared to use a 3/8” drive with an extension and a 17mm claw foot head. As it turned out, the dampener o-ring was shot and the
dampener was already loose. I just spun it off with my fingers. I did use the claw foot head with the extension and torque wrench when I installed the new dampener.
2007 SL550 Pulsation dampener
Thank you. I am not so lucky. Mine seems seized. And no O-ring supplied by MB part dealer in KC, MO. Do you happen to know O-ring part number? Here is a picture of the dampener part. I don't see how it attaches to the pump. Is it like yours?
Well, it’s just upside down . Be sure that you check the threaded portion to see if the tiny o-ring isn’t already installed. I think that they are usually shipped with the o-ring in place.
Thanks for all your help. The 22 mm bolt end is a shipping cap used to protect the threads once I removed it I could see how everything could be removed and replaced. Now I am contemplating what to do with the $1500 plus plus still in my pocket. Thanks again.
Hey guys, just wanted to pop in and say thanks for the descriptions here — started hearing/feeling something funny with my car last week and suspected this might be it.
Does anyone know what I can expect to pay to have an indie take care of this? I usually DIY but not a lot of time right now...
edit—I went and took another peak at my engine bay. It looks to me like I should be able to get this out without moving much of anything? Seems like access to the pump is a lot easier with M113K than M273 powered cars. Anything I’m missing here?
Hey guys, just wanted to pop in and say thanks for the descriptions here — started hearing/feeling something funny with my car last week and suspected this might be it.
Does anyone know what I can expect to pay to have an indie take care of this? I usually DIY but not a lot of time right now...
edit—I went and took another peak at my engine bay. It looks to me like I should be able to get this out without moving much of anything? Seems like access to the pump is a lot easier with M113K than M273 powered cars. Anything I’m missing here?
Using the techniques outlined in this thread, buying and replacing the dampener is an inexpensive and quick DIY job. You can benefit from what we learned by trial and error. However, it's pretty certain that you will still need to move some things around to get the dampener off.
Be aware that replacement of the dampener may not solve your problem. If it is the original 2008 dampener (as mine was), it is due for replacement at this point, in any case.
If you decide to pay someone to do it, make sure that you pick someone knowledgeable about these systems. A lot of damage can be done by the tiniest bit of dirt contaminating the hydraulic fluid and connections. Cleanliness is essential at all stages!
Note that the "official" procedure is to remove the pump and then turn it upside down before swapping the pulsation dampener. This is to prevent any contaminants from getting into the pump. Personally, I believe that if you are very careful and thoroughly clean the pump and dampener before replacement, this is not necessary and it can be done as described here. However, a shop may want to follow the official procedure, which will easily add several hours to the job. If you can't DIY and the shop insists on removing the pump, then you might as well get them to do a fluid flush and filter change all at the same time as they would have to add fluid anyhow.
Note that the "official" procedure is to remove the pump and then turn it upside down before swapping the pulsation dampener. This is to prevent any contaminants from getting into the pump. Personally, I believe that if you are very careful and thoroughly clean the pump and dampener before replacement, this is not necessary and it can be done as described here. However, a shop may want to follow the official procedure, which will easily add several hours to the job. If you can't DIY and the shop insists on removing the pump, then you might as well get them to do a fluid flush and filter change all at the same time as they would have to add fluid anyhow.
I agree with Rudeney on the above quote, dirt is the biggest enemy of the ABC system.
On my car it started with a white warning, "ABC off line" or something like that, I don't remember exactly, and the car was acting like a rocking horse. Next morning the car acted normal, but after a few day's the whining started. Tried change the pulsation damper, but no improvement. Changed the pump, flushed the system, changed the filter twice, and everything is fine, and has been since. That is now 3 month ago.
I followed Mr. Rudeny's procedure and it was not that time consuming, even first time through. 2-3 hrs top side. My dampener was really tightly torqued on the pump and I did not want to use any penetrate fearing contamination if any got into ABC pump. Cleaning around dampener before removal is required!
It is possible M113 engines give more access and require fewer unbolts and moving things to get access, not sure.
I would feel more comfortable doing this job than I would having my indie do it, he's good, but still charges!. He did my Engine and Tranny mounts which I did not want to take on without a lift..
Thanks all! Appreciate the advice. So, for reference, here’s what it looks like in my engine bay. All I think I really have to do is remove the air intake tube and move a couple of lines aside and it’s right there:
(front of car is at top of image)
Also, I’m uploading a video with the sound I’m getting from inside the cabin and one of my engine running from outside. As others have noted, can’t really hear the whining from outside, and it’s not immediately present from a cold start.
04-13-2018, 04:01 PM
. Be sure that you check the threaded portion to see if the tiny o-ring isn’t already installed. I think that they are usually shipped with the o-ring in place.
