noise from the ABC pump and foaming power steering fluid
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S550 W221
noise from the ABC pump and foaming power steering fluid
Hello. I've had a problem for almost a year. The noise of the ABC tandem pump is as shown in the link below. The Pentosin CHF fluid and the ABC filter were replaced, the system was flushed, and a rodeo test was performed. Unfortunately, the symptoms did not subside. The mechanic's verdict was the ABC pump. was replaced, but still the same, then we replaced the pulsation dumper but the pump makes noise. The ABC pump pressure is correct, there are no errors, the suspension works properly, it raises and lowers. There is no loss of fluids, no leaks. I have no more ideas where to look for the cause. Do you have any ideas where else I can look for the problem? The noise is more intense when turning the steering wheel. This does not occur when lowering and raising the suspension.
Link for video:
Link for video:
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2006 W221 S500L M273
In the 2nd video you can see that the power steering reservoir is filled with white foam.
(Just to make sure) is the power steering circuit also filled with CHF11S, Przemo91?
Thread Starter
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S550 W221
But the accumulators and pulsation dampers are all in the ABC circuit and not the power steering circuit, right?
In the 2nd video you can see that the power steering reservoir is filled with white foam.
(Just to make sure) is the power steering circuit also filled with CHF11S, Przemo91?
In the 2nd video you can see that the power steering reservoir is filled with white foam.
(Just to make sure) is the power steering circuit also filled with CHF11S, Przemo91?
Thread Starter
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Joined: Apr 2024
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S550 W221
I was convinced that it was the same system, do you know the fluid replacement procedure or do you have a manual on how to replace the fluid in the power steering system? I know ABC fluid replacment
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S550 W221
Thanks a lot for your time and manual pdf. This is for the Airmatic version. This makes me wonder why I can't find the ABC version? I can't find information anywhere whether the tandem pump has the same fluid? Although why would there be two tanks with an oil level gauge?
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From: Phoenix
222 S-65
It is power steering making noise and foaming fluid. I may suffer from reading comprehension issues. Stranger has happened.
Airmatic cars will not have the duo-pump.
Power steering foaming fluid will have to be air getting in via the return circuit or via the front seal on the pump. Any leaks in the return line to the pump?
I always used ZHM in power steering and ABC until the 222 car which uses a different fluid for MBC and electric power steering. :-(
Airmatic cars will not have the duo-pump.
Power steering foaming fluid will have to be air getting in via the return circuit or via the front seal on the pump. Any leaks in the return line to the pump?
I always used ZHM in power steering and ABC until the 222 car which uses a different fluid for MBC and electric power steering. :-(
Thread Starter
Newbie
Joined: Apr 2024
Posts: 10
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S550 W221
It is power steering making noise and foaming fluid. I may suffer from reading comprehension issues. Stranger has happened.
Airmatic cars will not have the duo-pump.
Power steering foaming fluid will have to be air getting in via the return circuit or via the front seal on the pump. Any leaks in the return line to the pump?
I always used ZHM in power steering and ABC until the 222 car which uses a different fluid for MBC and electric power steering. :-(
Airmatic cars will not have the duo-pump.
Power steering foaming fluid will have to be air getting in via the return circuit or via the front seal on the pump. Any leaks in the return line to the pump?
I always used ZHM in power steering and ABC until the 222 car which uses a different fluid for MBC and electric power steering. :-(
There are no fluid leaks, the ABC pump has been regenerated, the only place it can discharge fluid is the power steering tank. I changed the cap as well
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2006 W221 S500L M273
In this case you're not looking for fluid leaks, you'll want to check if air can enter the low-pressure power steering lines(s) somewhere.
Like JohnLane said: "Power steering foaming fluid will have to be air getting in via the return circuit or via the front seal on the pump."
Like JohnLane said: "Power steering foaming fluid will have to be air getting in via the return circuit or via the front seal on the pump."
Thread Starter
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S550 W221
Foam in the liquid theoretically indicates this, and the sound of the pump indicates air in the system. I will look again because I have already inspected the hydraulic connections at the ABC pump. The return circuit to the power steering reservoir is the larger hole or the smaller one?
Thread Starter
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Joined: Apr 2024
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S550 W221
Foam in the liquid theoretically indicates this, and the sound of the pump indicates air in the system. I will look again because I have already inspected the hydraulic connections at the ABC pump. The return circuit to the power steering reservoir is the larger hole or the smaller one?
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From: Portland, Oregon
2009 S600 V-12
Foam in the liquid theoretically indicates this, and the sound of the pump indicates air in the system. I will look again because I have already inspected the hydraulic connections at the ABC pump. The return circuit to the power steering reservoir is the larger hole or the smaller one?
Steering to the limits can blow the seals out of most hydraulic power steering pumps. You will hear the pump make high pitch noise when in that zone of destruction. When I get into that over pressure zone, I immediately steer out enough to hear normal operation of pump. Seals internal could be damaged and sucking air internally into system causing the sudsing you describe.
Electric steering is immune to over pressure when steering the wheel full left/right. No hydraulics.
If the car is being driven like that, it will never be healed.
Johnny
Last edited by johnnyrocket52; Apr 20, 2024 at 01:17 AM.
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S550 W221
Sometimes the steering wheel was turned to the limit but immediately went back, I don't think it destroys the pump every time. Which external seals exactly do you mean? I would like to point out that the pump sometimes stops making sounds for a while, after driving e.g. 50 km in an urban cycle, after turning off the ignition several times.
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From: Portland, Oregon
2009 S600 V-12
Sometimes the steering wheel was turned to the limit but immediately went back, I don't think it destroys the pump every time. Which external seals exactly do you mean? I would like to point out that the pump sometimes stops making sounds for a while, after driving e.g. 50 km in an urban cycle, after turning off the ignition several times.
Example, inside the reservoir, above the P/S pump fluid, is air head space at atmospheric pressure, accounting for thermal expansion of fluid. Somehow a component venting back to the head space is sucking air from there?
Is the correct P/S fluid, not contaminated with moisture being used?
Make sure it’s not Aunt Mildred’s sewing machine oil…
Best
Johnny
Last edited by johnnyrocket52; Apr 20, 2024 at 05:09 PM.
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W221 S63 AMG (2007)
Have a new ABC pump but sometimes stil steering goes heavy and after a sprint the steering wheel shakes when trying to steer (not in straight posision), only when warm and shut down for 10 minutes and start again it moans for a few seconds.
No idea whats going on but replacing the reservoir is the firts thing to do.
Last edited by dim70; Dec 3, 2024 at 12:48 PM.
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