SL/R230: ABC Pump Knocking
Thread Starter
Newbie
Joined: Jun 2023
Posts: 2
Likes: 0
2006 SLK 55 AMG, 2005 SL 500, ‘99 SLK 230
ABC Pump Knocking
Hi all,
I recently bought a fixer-upper SL 500 (2005) and have donated way too much time into making it good again.
After fixing most of the problems, I’m left with just a couple, with the prominent being a knocking noise coming from the ABC pump area.
Here’s what I know so far:
- A mechanics stethoscope pointed me in the direction of the pump having the knocking noise originally.
- I had an ABC line explode which nuked the suspension and drained the oil, which I have since fixed, but during the time where there was no ABC fluid, the pump was silent. (It had knocked before this event).
- During raising/lowering of the car, the sound of the knocking changes slightly.
- While driving the car, if I hit a large bump
in the road, I am greeted by a red ABC warning which says “drive carefully” which sticks around for only a couple seconds. (This was the same warning I received when the hose exploded except it did not go away).
-From what I can tell, the suspension works great now, but the sound and the red warning are disheartening. (System pressure sensor reads 180-190 bar).
When I was fixing the hose and trying to bleed the car, the noise was quiet until the pressure actually started to build, regardless of whether or not there was fluid in the tank.
Calling all ABC wizards; playing parts darts in this situation would more than likely exhaust my savings account! XD
I recently bought a fixer-upper SL 500 (2005) and have donated way too much time into making it good again.
After fixing most of the problems, I’m left with just a couple, with the prominent being a knocking noise coming from the ABC pump area.
Here’s what I know so far:
- A mechanics stethoscope pointed me in the direction of the pump having the knocking noise originally.
- I had an ABC line explode which nuked the suspension and drained the oil, which I have since fixed, but during the time where there was no ABC fluid, the pump was silent. (It had knocked before this event).
- During raising/lowering of the car, the sound of the knocking changes slightly.
- While driving the car, if I hit a large bump
in the road, I am greeted by a red ABC warning which says “drive carefully” which sticks around for only a couple seconds. (This was the same warning I received when the hose exploded except it did not go away).
-From what I can tell, the suspension works great now, but the sound and the red warning are disheartening. (System pressure sensor reads 180-190 bar).
When I was fixing the hose and trying to bleed the car, the noise was quiet until the pressure actually started to build, regardless of whether or not there was fluid in the tank.
Calling all ABC wizards; playing parts darts in this situation would more than likely exhaust my savings account! XD
Super Member
Joined: Sep 2018
Posts: 746
Likes: 182
From: Melbourne, Australia
2005 SL 500 R230
Most of us know about way too much time. Take heart though, nearly there...
After fixing most of the problems, I’m left with just a couple, with the prominent being a knocking noise coming from the ABC pump area.
The pumps get noisy as they age but can still put out good pressure. A new pump will fix it. I had same symptoms - same fix. When you're in there replacing the pump, inspect the bronze gauze net inside the banjo bolt on the pump outlet for any metal shavings that may have been deposited when the hose blew (unlikely though).
While driving the car, if I hit a large bump in the road, I am greeted by a red ABC warning which says “drive carefully”
That's a sure sign of failed pressure accumulators - front or rear or both. Replace them.
After fixing most of the problems, I’m left with just a couple, with the prominent being a knocking noise coming from the ABC pump area.
The pumps get noisy as they age but can still put out good pressure. A new pump will fix it. I had same symptoms - same fix. When you're in there replacing the pump, inspect the bronze gauze net inside the banjo bolt on the pump outlet for any metal shavings that may have been deposited when the hose blew (unlikely though).
While driving the car, if I hit a large bump in the road, I am greeted by a red ABC warning which says “drive carefully”
That's a sure sign of failed pressure accumulators - front or rear or both. Replace them.
Super Member
Joined: Aug 2017
Posts: 519
Likes: 203
From: Scottsdale AZ
2015 SL550 & 2012 S550 4matic
Hey Steven, I suggest you replace the pulsation dampener as well if you have not already. Yours is mounted in driver side front wheel well, mine is newer version and mounted on the pump. Their purpose is to smooth out the variation in pressure when pump starts. Replacing mine made things quiet again.
Thread Starter
Newbie
Joined: Jun 2023
Posts: 2
Likes: 0
2006 SLK 55 AMG, 2005 SL 500, ‘99 SLK 230
Most of us know about way too much time. Take heart though, nearly there...
After fixing most of the problems, I’m left with just a couple, with the prominent being a knocking noise coming from the ABC pump area.
The pumps get noisy as they age but can still put out good pressure. A new pump will fix it. I had same symptoms - same fix. When you're in there replacing the pump, inspect the bronze gauze net inside the banjo bolt on the pump outlet for any metal shavings that may have been deposited when the hose blew (unlikely though).
While driving the car, if I hit a large bump in the road, I am greeted by a red ABC warning which says “drive carefully”
That's a sure sign of failed pressure accumulators - front or rear or both. Replace them.
After fixing most of the problems, I’m left with just a couple, with the prominent being a knocking noise coming from the ABC pump area.
The pumps get noisy as they age but can still put out good pressure. A new pump will fix it. I had same symptoms - same fix. When you're in there replacing the pump, inspect the bronze gauze net inside the banjo bolt on the pump outlet for any metal shavings that may have been deposited when the hose blew (unlikely though).
While driving the car, if I hit a large bump in the road, I am greeted by a red ABC warning which says “drive carefully”
That's a sure sign of failed pressure accumulators - front or rear or both. Replace them.
Is there a method to check which accumulator has failed or would it just be wise to replace both?
Super Member
Joined: Sep 2018
Posts: 746
Likes: 182
From: Melbourne, Australia
2005 SL 500 R230
There might be a code in STAR or on your scanner if you have one - I don't know - that tells you whether it's front or rear.
But. Failed accumulators can lodge bits of rubber diaphragm in the system that block the pipes. I have seen videos where it's happened, but you'd have to be unlucky. Failed accumulators load up the system and can burst hoses so it's prudent to replace both. Corteco brand is the go if you don't want to go genuine. They're not that expensive.
But. Failed accumulators can lodge bits of rubber diaphragm in the system that block the pipes. I have seen videos where it's happened, but you'd have to be unlucky. Failed accumulators load up the system and can burst hoses so it's prudent to replace both. Corteco brand is the go if you don't want to go genuine. They're not that expensive.
Junior Member
Joined: Aug 2022
Posts: 32
Likes: 1
2005SL500
Hi Steven,
I also have a 2005 SL500 with 97K miles, no exploded ABC lines but with new accumulators and still have the knocking sound from the ABC pump after the car warms up. I don't know the age of my pump. I've never had an ABC warning.
Which of your line exploded - I'd like to know for reference. How did you repair or replace it?
Did you replace your ABC pump? Which supplier did you use? How is it going so far?
There are so many people trying to supply these ABC rebuilt tandem pumps. I don't trust any of them. I'm trying to research which one to buy when the time comes.
I also have a 2005 SL500 with 97K miles, no exploded ABC lines but with new accumulators and still have the knocking sound from the ABC pump after the car warms up. I don't know the age of my pump. I've never had an ABC warning.
Which of your line exploded - I'd like to know for reference. How did you repair or replace it?
Did you replace your ABC pump? Which supplier did you use? How is it going so far?
There are so many people trying to supply these ABC rebuilt tandem pumps. I don't trust any of them. I'm trying to research which one to buy when the time comes.
Senior Member
Joined: Apr 2007
Posts: 431
Likes: 79
Former R230, W220 and W221 owner
https://mbworld.org/forums/sl-class-...placement.html
here's the way to diagnose. We know one is bad because you get errors going over bumps but replace both and the dampener and get it over with. Also, a bad accumalator will push fluid back to the reservoir and you will have ABC fluid all over the place
https://www.youtube.com/shorts/nciTuKYtM10
here are the parts you need:
Two of these:
https://www.fcpeuro.com/products/mer...tor-2203270115
Pulsation Dampener:
https://www.fcpeuro.com/products/mer...tor-2203270215
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Senior Member
Joined: Dec 2002
Posts: 346
Likes: 20
From: Florida
W124, W126, W140, W220, W222, R129
Hi Steven,
I also have a 2005 SL500 with 97K miles, no exploded ABC lines but with new accumulators and still have the knocking sound from the ABC pump after the car warms up. I don't know the age of my pump. I've never had an ABC warning.
Which of your line exploded - I'd like to know for reference. How did you repair or replace it?
Did you replace your ABC pump? Which supplier did you use? How is it going so far?
There are so many people trying to supply these ABC rebuilt tandem pumps. I don't trust any of them. I'm trying to research which one to buy when the time comes.
I also have a 2005 SL500 with 97K miles, no exploded ABC lines but with new accumulators and still have the knocking sound from the ABC pump after the car warms up. I don't know the age of my pump. I've never had an ABC warning.
Which of your line exploded - I'd like to know for reference. How did you repair or replace it?
Did you replace your ABC pump? Which supplier did you use? How is it going so far?
There are so many people trying to supply these ABC rebuilt tandem pumps. I don't trust any of them. I'm trying to research which one to buy when the time comes.
