S500L 2001 ABC Pump repair
Thread Starter
Junior Member
Joined: Sep 2012
Posts: 17
Likes: 4
From: Bulgaria
Mercedes S500L (W220) and ML63 AMG (W164)
S500L 2001 ABC Pump repair
Hi all,
I have a strange humming noise comming from the ABC Pump. Yesterday I was at an official MB Dealer, where they stated that it might be the pump bearing thats making this noise. Is there a way of taking the pump apart and repairing it? Have anyone done this?
I saw in Germany old pumps being repaired and sold as new with warranty, where you have to give them your old pump in order to buy the new one. So there should be a way of repairing the stuff. MY is 2001 prior to facelift.
Best Regards,
Svetlio
I have a strange humming noise comming from the ABC Pump. Yesterday I was at an official MB Dealer, where they stated that it might be the pump bearing thats making this noise. Is there a way of taking the pump apart and repairing it? Have anyone done this?
I saw in Germany old pumps being repaired and sold as new with warranty, where you have to give them your old pump in order to buy the new one. So there should be a way of repairing the stuff. MY is 2001 prior to facelift.
Best Regards,
Svetlio
Super Member
Joined: Aug 2010
Posts: 986
Likes: 6
From: Kingsville Ontario (South of Detroit)
2003 S500 4Matic (SOLD) + 2004 S55 (SOLD) 2005 CLK 500 Cabriolet 2008 S 450
There is a simple way of determining if it is pump bearings. While the car is running , very carefully put a long screw driver against the pump body and hold your ear up to the screw driver. the screw driver acts as a stethoscope and allows you to hear the internal workings. Be very very careful when placing the screw driver in position. Obviously with rotating parts there is potential for catching the screw driver up in the rotating parts. The pump is a dual; purpose pump. It serves as ppower steering pump and ABC pump. Your peoblem may be the ABC pulsation damper which can create a humming noise. There is a rubber diaphragm inside the damper that over time can develop a leak. This reasults in a humming noise, quite often around 2000 rpm and also when in iots final stage of live, result in a harsh ride. I'm no expert but I am going through a series of issues with my ABC system so I've gone through a lot of investigation tying to pinpoint the real issue. Good luck with your repair.
Thread Starter
Junior Member
Joined: Sep 2012
Posts: 17
Likes: 4
From: Bulgaria
Mercedes S500L (W220) and ML63 AMG (W164)
Thanks Bobby,
I have already done this with the screw driver and I'm hearing the noise from there... Right now i'm also thinking about the pulsation damper and want to check it out. If the sound is cause by the pulsation damper, will the vibrations be felt on the pump, or on the valve where the pulsation damper is? It is sitting at a distance from the pump, so I wanna know if the damper is defect, will it cause the noise to be recognized with the screw driver on the pump, or on itself??
Thanks,
Svetlio
I have already done this with the screw driver and I'm hearing the noise from there... Right now i'm also thinking about the pulsation damper and want to check it out. If the sound is cause by the pulsation damper, will the vibrations be felt on the pump, or on the valve where the pulsation damper is? It is sitting at a distance from the pump, so I wanna know if the damper is defect, will it cause the noise to be recognized with the screw driver on the pump, or on itself??
Thanks,
Svetlio
Super Member
Joined: Aug 2010
Posts: 986
Likes: 6
From: Kingsville Ontario (South of Detroit)
2003 S500 4Matic (SOLD) + 2004 S55 (SOLD) 2005 CLK 500 Cabriolet 2008 S 450
The pulsation damper is "downstream from the ABC pump and therefore the noise probably will not be evident at the pump but rather at the damper.
MBWorld Fanatic!
Joined: Dec 2012
Posts: 2,474
Likes: 439
From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
It is normal for pressure pulsations to be heard throughout a hydraulic system. That is, if the pulsation damper fails, the pulsations might well be heard at the pump (where the pulsations originate).
Super Member
Joined: Aug 2010
Posts: 986
Likes: 6
From: Kingsville Ontario (South of Detroit)
2003 S500 4Matic (SOLD) + 2004 S55 (SOLD) 2005 CLK 500 Cabriolet 2008 S 450
Again I'm no expert. but having said that, I believe the pulses originate at the damper not at the pump. I doubt whether yo could hear the pulsation echo at the pump, but then again my ears are pretty old.
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Thread Starter
Junior Member
Joined: Sep 2012
Posts: 17
Likes: 4
From: Bulgaria
Mercedes S500L (W220) and ML63 AMG (W164)
Hi all,
I checked the pulsation dampers and there was absolutely no sound comming from them. The buzzing sound is coming straight of the pump, and if you look at it for a while, you can see it vibrating along with the sound.
If I turn off the AC compressor, it seems that the sound isnt anymore repeating in stages, but being almost continious, or even sometimes gone. If I press on the gas pedal to raise the RPM of the engine, the sound is gone. You can hear it only on Idle - at about 550-600 rpm... Anything above 800 rpm is canceling the sound.
I'm thinking if it can be a faulty bearing, so that when the AC is on, it puts more stress on the V-Belt and on the ABC Pump bearing.
What do you guys think? Are these pumps bearings repairable, or should I just change the pump?
Best Regards,
Svetlio
I checked the pulsation dampers and there was absolutely no sound comming from them. The buzzing sound is coming straight of the pump, and if you look at it for a while, you can see it vibrating along with the sound.
If I turn off the AC compressor, it seems that the sound isnt anymore repeating in stages, but being almost continious, or even sometimes gone. If I press on the gas pedal to raise the RPM of the engine, the sound is gone. You can hear it only on Idle - at about 550-600 rpm... Anything above 800 rpm is canceling the sound.
I'm thinking if it can be a faulty bearing, so that when the AC is on, it puts more stress on the V-Belt and on the ABC Pump bearing.
What do you guys think? Are these pumps bearings repairable, or should I just change the pump?
Best Regards,
Svetlio
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Thread Starter
Junior Member
Joined: Sep 2012
Posts: 17
Likes: 4
From: Bulgaria
Mercedes S500L (W220) and ML63 AMG (W164)
Hi all,
I just made some videos, so you can hear the sound comming out of the pump.
In the first video, I tried amplifying the sound with a "stethoscope"
Best Regards,
Svetlio
I just made some videos, so you can hear the sound comming out of the pump.
In the first video, I tried amplifying the sound with a "stethoscope"
Best Regards,
Svetlio
Super Member
Joined: Aug 2010
Posts: 986
Likes: 6
From: Kingsville Ontario (South of Detroit)
2003 S500 4Matic (SOLD) + 2004 S55 (SOLD) 2005 CLK 500 Cabriolet 2008 S 450
Boy that sure does sound like pump. I've seen a seal kit for the pumps here on the forum. From what I've read and from talking to my Indie it seems the greatest problem in any potential pump repair is getting the pulley off the pump so that it can be disassembled. According to my Indie they broke a bearing puller trying to remove the pulley.
There is a thread here that talks about heating the pulley cherry hot to remove and then putting the pulley in the freezer for a period of time before repositioning it back onto the pump shaft.
Typically it is the seals that become brittle and start to allow internal leakage. I don't believe this would cause noise but more likely would show itself as losing suspension height or total drop down.
Again I am not an expert.
There is a thread here that talks about heating the pulley cherry hot to remove and then putting the pulley in the freezer for a period of time before repositioning it back onto the pump shaft.
Typically it is the seals that become brittle and start to allow internal leakage. I don't believe this would cause noise but more likely would show itself as losing suspension height or total drop down.
Again I am not an expert.
MBWorld Fanatic!
Joined: Dec 2012
Posts: 2,474
Likes: 439
From: Ball Ground, GA (N of Atlanta)
2003 S500 2007 GL450
Freezing the pulley before installation won't work. That would increase, not decrease, the interference and make it much more difficult to install. If you did manage to force it on the shaft without damaging the pump, the fit would be looser than if you put it on at room temp, and much looser than if you heated the pulley before installation.
Thread Starter
Junior Member
Joined: Sep 2012
Posts: 17
Likes: 4
From: Bulgaria
Mercedes S500L (W220) and ML63 AMG (W164)
Hi all,
Yesterday I made some more tests on the car with a Star Diagnosis.
The pump is reaching the needed pressure of 200 bar, but if I set up a rodeo accutation the pressure falls down to about 65 bar only after the first 5 seconds, and the pump isn't making anymore pressure for the whole rodeo. That means, that after the first five seconds where it fully rises and lowers the car on each side - it gets to 65 bar and can't rise the car fully, so it basically sits on its tires and barely moves and inch or two(instead of moving about 5-6 inches when 200 bars are reached).
Also, when the pump's pressure falls down during the rodeo, the noise disappears and can't be heard anymore. Once I stop the it, the pressure continiously rises and once above 130 bar you can hear the same noise again. I remember that in the past doing a rodeo rises and lowers the whole car like it should the whole time. Now the pump can't hold its pressure after the first 5 seconds, so it must be of an internal leak and a loosen part inside the pump.
I'm thinking of ordering the following kit in order to try repair the pump myself:
http://www.invasionautoproducts.com/mebeabcpusek.html
To get the flange out, I should heat it to almost glowing red, so it can expand enough and get out.... In order to put it back on, the whole pump should be left in the freezer overnight so it can shrink as much as possible, and then the flange should be heated again so that it expands.
I will order the seals kit right now, but it will take a while until they get to Bulgaria...
Best Regards,
Svetlio
Yesterday I made some more tests on the car with a Star Diagnosis.
The pump is reaching the needed pressure of 200 bar, but if I set up a rodeo accutation the pressure falls down to about 65 bar only after the first 5 seconds, and the pump isn't making anymore pressure for the whole rodeo. That means, that after the first five seconds where it fully rises and lowers the car on each side - it gets to 65 bar and can't rise the car fully, so it basically sits on its tires and barely moves and inch or two(instead of moving about 5-6 inches when 200 bars are reached).
Also, when the pump's pressure falls down during the rodeo, the noise disappears and can't be heard anymore. Once I stop the it, the pressure continiously rises and once above 130 bar you can hear the same noise again. I remember that in the past doing a rodeo rises and lowers the whole car like it should the whole time. Now the pump can't hold its pressure after the first 5 seconds, so it must be of an internal leak and a loosen part inside the pump.
I'm thinking of ordering the following kit in order to try repair the pump myself:
http://www.invasionautoproducts.com/mebeabcpusek.html
To get the flange out, I should heat it to almost glowing red, so it can expand enough and get out.... In order to put it back on, the whole pump should be left in the freezer overnight so it can shrink as much as possible, and then the flange should be heated again so that it expands.
I will order the seals kit right now, but it will take a while until they get to Bulgaria...
Best Regards,
Svetlio
Super Member
Joined: Aug 2010
Posts: 986
Likes: 6
From: Kingsville Ontario (South of Detroit)
2003 S500 4Matic (SOLD) + 2004 S55 (SOLD) 2005 CLK 500 Cabriolet 2008 S 450
Good luck on the repair. Please keep us informed with the details of the repair. Pictures would be great. Pump failure is certainly not unheard of and these details especially with pictures would be of great benefit to myself and other ABC owners.
