Zach8131

Hi everyone, I recently picked up a 2003 S600 a few weeks ago, the odometer has a few miles on the clock but everything else is golden and only one owner before me (a corporate car)

Anyway there is an ANNOYING humming coming from under the driver side area mostly. I cannot hear it as much when my fiance is driving and I am in the passenger seat.

IT DRIVES ME INSANE. I was recently at my indy shop that only does Mercedes and I had a suspension flush, brake flush, and two "pressure cells" replaced. Each "cell" was $195. It has a part number 220327115 label on it. Is that the same as the pulsation damper? I was reading other posts and was told that the pulsation damper causes this noise, but if I already had them replaced, then I am going to chop off my arm because this noise makes the beast unlivable.

Thanks in advance for your responses!

tusabes

Damper is different from the pressure cells (aka accumulators)

You probably needed new accumulators anyway so it was just preventative maintenance not a waste

s5benzo

Zach 2203270115 are the accumulators.... If your feeling slight vibrations with annoying wining or humming sound then im definite it is the pulsation damper. 2203270215 is the part number for that . This is located on the passenger front side of the vehicle . Pretty simple job if you are a diy guy . Good luck

Zach8131

Thanks guys, I replaced the damper today and as stated before also replaced the pressure cells. There is only one damper correct? Because the noise (while a tad better) is STILL there increasing its whine with the RPM's! Do I have to rodeo the car after installing the new damper or do I just need to set it on fire? Thanks

Ps, if you can't tell already-- I hate non-essential noises.

wallyp

I don't have an ABC vehicle, so this might be nonsense, but perhaps it would be a good idea to carefully check all of the ABC plumbing to see if a tube or hose is resting against the body or chassis.

w4sim

Mine was making the exact same noise which got louder with the RPM's, but once i replaced the pulsation damper then everything was fine, noise completely disappeared.

Problem is that the noise sounds exactly the same as a wheel bearing on its way out. Since i could not tell the difference between the 2 i did a simple test to see which one it could be.

1. Drive the car upto about 40mph (downhill would be best).
2. Gently put it into "Neutral"
3. If the noise stops as the RPM's drop then its the Pulsation damper.
4. If the noise remains as the RPM's drop then its a wheel bearing.

Zach8131

Thanks Wallyp, I will try to check out the lines. I would have never thought of that.

Now, w4sim, the noise does go away when I slip the car I to neutral. The noise is still isolated in the engine area and I can hear it slightly as if it is far away still decreasing as the RPM's lower. Whatever gets disconnected when the car goes into neutral separates me from the noise.

I was told my passenger wheel bearing is good today when the shop replaced the damper so I guess I should have the driver side looked at.

G.AMG

I had the same issue when I bought my car 6 months ago. After some investigation I found the fuel pump was making the annoying humming sound coming from under the drivers side of the car, I swapped the pump and filter out for new units and the noise went away.

Zach8131

Interesting that the fuel pump was making a noise under the driver side area? Hmm... I guess I will drop the car for a fuel pressure test as well as getting everything else looked at.

Does anyone think it would be wise to just lay Mercedes their ridiculous $375 diagnosis fee so they can tell me everything wrong with my car so I have a legitimate and solid list to go off of?

wallyp

Comments on the diagnostic:

I am going for a haircut in just a few minutes. Shannen (my barber) has a sign on her mirror - "Never ask a barber if you need a haircut". Good thought - running the diagnostics will give an excellent opportunity to sell you some repairs...

Price sounds high. I would check for a good indy tech who can do the test.

On the other hand, you will need to pay for the time that it takes, which could be just a few minutes for a quick look, or an hour or more for an exhaustive examination. You need to get a printout.

I would not expect the diagnostic to show what is making the noise. The diagnostic consists of asking the multiple computers on the car if they have noticed any problems. I haven't seen any noise sensors while I was running diagnostics. There could be an indirect indication, such as low pressure on one of the systems.

G.AMG

Fuel pressure won't necessarily be lower because the pump is making noise. Get in your car and turn the key to the on position right before cranking and listen for the fuel pump to prime for a few seconds (make sure to turn the radio off and close all doors so you can hear better). This is how I originally diagnosed the pump was making the noise I heard, next step is to get under the car, remove the plastic panel which covers the pump and listen for the noise while someone turns the key on in the car.

w4sim

You say you've replaced the damper already, did you do a Rodeo test on it (a cheaper way is to raise and lower the car with the inside button about 25 times).

And did you also top up the ABC fluid as low fluid could also do this?

Zach8131

True Wallyp, true. Mercedes of Anaheim told me the car wouldn't connect to their EIS(?) machine, so it wouldn't tell them what kind of key I needed when I tried to get a new key & card. Tried to sell me on the diagnostic then too.

G.AMG, I'll try that out. I forgot that I had to do this with my CLK500 because the pump had completely died. Now is the 600 one internal or external? I would assume internal because that's what all my other ones are.

W4sim, no I didn't rodeo after replacing the damper 1) because the shop that did it didn't have stars, & 2) I had just done it a few days prior with the fluid flush and pressure cell replacement. I will try it the cheap way today, and as for fluid, the tech placed his finger over the line so the only fluid lost was under a teaspoon (unless the old damper was full of fluid) I will check the dipstick. If I overfill fluid, the car will just burp out everything it doesn't like through the pin-sized overflow, right?

G.AMG

I'm pretty sure all of the W220's have an external fuel pump located under the drivers side of the car.

Zach8131

G, from the diagrams I've seen it looks to be right under my butt. How annoying (if that is the true culprit) and will explain why everyone else couldn't hear it and called me crazy.

G.AMG

If that turns out to be your problem make sure to purchase a new pump and filter. The parts shouldn't run you more than $400, and about an hour of your time to swap them out. Here's a quick DIY for the fuel filter, pump is pretty uch right next to the filter

Zach8131

I actually JUST watched that before posting my last comment. Haha. I called my dealership and parts will cost me just shy of $200 so I might just do it even if it's not the problem! I had a fuel pump die on me out of nowhere and I am pretty paranoid now.

Zach8131

Here is a video of the car. If you turn up the volume you can hear the moan/groan. It's worse in person!

youtube.com/watch?v=QY8Smzc5wW4

G.AMG

Wow that sounds more like a power steering pump to me.

Zach8131

That's what I'm afraid of, because it's shares with the suspension pump in tandem which will cost me $1,500 to fix

G.AMG

Did you try popping the hood and locating the sound while idling?

Zach8131

Yes, you cannot hear it unless in the cabin.

G.AMG

Hopefully it's not transmission related

Zach8131

Me too, but don't you think it would have helped cure the noise a tad when I replaced the transmission mount and did a transmission service? Which I just did last week.

G.AMG

Who did the trans service? I would check the fluid level asap, remember having too much trans fluid can be just as bad as not having enough.