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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Discussion Starter #1
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.

 

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Current 2012 GLK350, 2009 SL550 Past 08 SLK55, 05 S600, 81 C280
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45 Posts
Thanks for writing this up Rodney. I’ll definitely add this to my kb as every little bit of info helps with these cars.
 

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2011 SL550 Black
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31 Posts
Man, you're an encyclopedia of knowledge on these R230s. Thanks for yet another great write up.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Discussion Starter #5
I have three desirable qualities: The ability to turn a wrench, a fearless desire to take things apart and put them back together, and a copy of WIS. :)
 

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2007 SL600 R230 M275 RennTech Tuned
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12 Posts
Very timely information for me also.

Thanks for sharing your process with us.
 

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2007 SL 550
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14 Posts
I am working on replacing damper on 2007 SL550
Instructions above are great, but I am not sure where the 3rd bolt is to loosen the pump.
I got the 2 bolts loose on the passenger side of pump.
Is the 3rd one on the back side of the pump?
Does it have a ground cable connected to it?

If that is it, did you get at it from underneath?

Thanks---Bill
 

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2007 SL 550
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14 Posts
Got It Loose!
Found third bolt/nut

13 mm nut.
Found it by feel ---couldn't see it
It is on bottom backside of pump.
Accessed it from underneath

Bill
 

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CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Discussion Starter #11
Yeah, I accessed the 3rd bolts from underneath, though I might could have done it by feel from above. The extra 5 minutes used lift the car probably saved me 10 minutes of blind frustration.
 

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Rodney did this require any fluid replacement (or flush)?

is there any pressure on this when removed to where it sprays fluid everywhere?

thanks in advance
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Discussion Starter #14
Note that the official procedure (for the MY2007+ facelift) is that the pump is to be removed and turned upside down before unscrewing the pulsation dampener. This is to prevent any debris from entering the pump. If you do it this way, you will lose some small amounts of fluid from the hoses and pump.

I did mine "in situ", just unbolting the pump and sliding it a few inches forward. I was extremely careful to thoroughly clean the area around the dampener in the pump to remove any trace of dirt. There was absolutely no spilling of fluid. Pressure in the pump dissipates quickly after shutting down the engine, but I think I do this on a cold engine anyhow to prevent getting burned by hot engine parts.
 

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CURRENT: 2011 SL550, 2011 C300 FORMER: ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Discussion Starter #16
Yes, the pulsation dampener was definitely the source of my whining noise.
 

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2007 SL550 (R230) and 2012 SClass Designo (W221)
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Thanks for the great write-up. I'm attempting the replacement of the pulsation dampener and having trouble with the part number. Can someone post the correct number for 2007 SL550? I have seen this on a mercedes parts site. Does this seem right?
Old Part Number 0004660310
New Part Number 000466040080
Part Name REMAN PULSATION DAMP
MSRP $230.00
Core $36.00
Online Price $171.47
 

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2007 SL 550
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14 Posts
I used the new part number that you listed that ends with 0080
when I did mine in February

I also have a Minnesota 2007 SL550
 

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2007 SL550 (R230) and 2012 SClass Designo (W221)
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Thanks for the confirmation. you are the second sl550 in MN on the forums. We plan a meetup soon. Care to join us? Send a pm if you want.
 

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2011 SL550
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160 Posts
I realize this was written several months ago. It popped up again recently and has me thinking. I have 2011. I hear an rpm-dependent whine/whir sometimes. Usually when hot. I suppose I can feel some vibration in the pedals, at least the brake pedal. Don't recall feeling anything in the steering wheel...will have to check that again. Do you believe it is possible to change out the dampener without loosening/sliding the pump? It does look all tightly packed. My car is low mileage (34k) but guessing many of these parts with rubber age as much with time as use.

I need to pay more attention to this but what you describe sounds similar to what I hear/feel. But I would not describe it as terribly loud. And I'm not sure I know what a differential in a big dump truck sounds like. Great write-up. Mark

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.

 
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