electrohydraulic pump repair instead of replace?
Photos below:
The skinny: could someone please help out with removing/ attempting to repair/ or replace and reinstall the w221 eletrohydraulic pump - any advice welcome

The details:
Some time recently i started getting quite the light show the dashboard, all malfunctions would appear, all dials would bounce around, all various dash symbols would come on and off
(shown in this YT video linked below)
I had it diagnosed at MB and they said there was a faulty wheel speed sensor however the source of all the problems was the electrodydraulic power steering pump.
I had the speed sensor replaced at a local indy since that was a cheap repair and I was hoping that it was indeed the sensor causing this electrical madness and not the $2000 pump.
That repair did not change much, and very shortly afterwards, the power steering was completely gone and this time there was only one message on the dash: 'Power Steering Malfunction See Oper. Manual' (btw I could not find such a malfunction in the owners book)
So I leave the car with some clever mechanic who is known for electrical magic stuff.
He gives me a call a day later and says the car is ready and working but no guarantees. Apparently he did some cleaning of the pump but nothing extensive. He further stated that a more thorough repair may be completed via removing the pump and sending it to some locals for soldering work inside the unit. I would have chosen this option from the start however I never got a call about options, just one saying to pick it up. Normally I'd be tough on any shop in this situation but I've been weak on confrontation recently.. where are my *****?! I paid the labor and took the car. (Even with the later fix, it's still a gamble)
Enjoyed driving for about a month when the light show came back, then went away for a little while, then one morning (after a spirited drive the night before (coincidence?(probably not))) the pump got the shakes, I would get the single msg: Power Steering, however this time I could hear and feel vibrations coming from where the the pump is located (right behind the front bumper cover, lower passenger corner.
I refuse to bite the bullet on a new pump! Not yet
I removed the skid plate, and wheel splash guard and tested to confirm. I pulled the green wire dedicated to power steering from the X30/30 chassis CAN/FFS voltage distributor (located behind the front passenger foot well.
When plugged in and car on, the pump vibrates bad, when unplugged no vibs.
So now the car is sitting as pictured and I am wondering about fixing and or removing/ replacing the pump myself.
Any-who I am wondering if anyone has any know how. Specific removal/ reinstall steps, bumper cover will probably need to come off. I'm guessing there may be hydraulic fluid that may need to be drained?
Making a last effort before replacing. Maybe it is something else that is causing the the problem. I've read about the wheel speed sensors doing weird things the the rest of the w221/w220
Over 2 years of enjoying this fine ride and this is the first real issue that I've faced.
Got it at 92,000 km, currently 125,000 km on the clock.
Thanks for reading, any feedback is appreciated!
( shown in this video:
location
there is an open hole on the side?..
bottom view
looks shady
Last edited by danielkon; Dec 21, 2019 at 05:50 PM.
can see some burned pins, notice the how the housing is rimmed with the powder, oh man..
those wires connecting the board to the machine look compromised (and worked on)
more powder on the floor
Trending Topics
The Best of Mercedes & AMG
Anything else IS a downgrade.
Bit of corrosion on the logic plug
Condensation inside




can see some burned pins, notice the how the housing is rimmed with the powder, oh man..
those wires connecting the board to the machine look compromised (and worked on)
more powder on the floor
Most of the problem for internal faults is from driver unit and resistors, replace and problem can be solved.


