Wonders

New member, recently purchased a 2007 S600 55k miles & full Mercedes history, trouble is steering intermittently goes heavy, car was serviced just before i bought it and have since have had 2 Mercedes main dealers check the steering and ABC/power steering pump they report no fault found, last dealer said ABC pumps don't fail by intermittently making steering go heavy.

I am concerned that this could be early signs of ABC pump failure

grateful for advise

ImInPA

ABC is for the suspension. It is a separate system from the power steering.

Wonders

yes i know, it's uses a tandem pump that controls both suspension and power steering - right?

ImInPA

No just the suspension. The power steering is separate.

Wonders

Wow, thought it was the same system, i was told would have to change ABC pump if steering failed, is W221 system different from W220 then, is the steering pump oil filled separately and does it carry a filter.

Wonders

ImInPA thanks for your help, i understand now the power steering uses a seperate reservoir which i check and found oil to be slightly low, topped up and thought may have been problem but i was wrong as steering has gone heavy again, any more advise please.

s5benzo

Wonders the ABC pump is a tandem pump and controls both suspension and steering ! They have two different reservoirs but share one pump. Either reservoir going dry is bad for the pump so keep the level correct. Maybe some sort of sensor is malfunctioning intermittently , say steering angle sensor? Hope u find the problem , good luck

Wonders

Previously owned a black 2001 W220 S600 that looked amazing but turned out to be a nightmare, i bought car in 2005 for 18K privately and soon noticed the oil cooler was leaking then ABC failed, then coil packs, starter motor, fan and body started to rust, car became so bad that my wife wouldnt sit in it, sold about a year later for £7000, bought a chysler 300c after that but couldnt resist buying another S600 but i'm a bit paranoid about the ABC system. hope heavy steering isnt gonna be major.

ImInPA

I am not familiar with the procedure, but, it is possible that there is air in the system. Perhaps bleeding the system and refilling would help. I the system could be pressurized, you could determine if there are any leaks. Perhaps a visit to a shop is in order. Wish I knew more.

Wonders

No leaks, does anyone know how to bleed power steering. thanks

Wonders

Still got intermittent heavy steering, help please.

konigstiger

Can not definitively diagnose without vehicle of course but two areas of "interest" would be valve to steering assembly may be malfunctioning or electrical connection damaged; and tandem pump (up to VIN A169441 pump was replaced with revised part # 0054667101 if applicable).

Wonders

thanks, am not getting any error codes, electrical connections would that be something to do with speed sensitive power steering.

Wonders

konigstiger, VIN A100942 so should have had revised pump right.

Wonders

Also checked power steering fluid level which was slightly low so topped up with the correct green fluid but noticed that oil in reservoir looked dirty, brown.

konigstiger

Possible misunderstanding MB recommends replacing original pump installed at production up to A169441 with revised part. Your VIN is within range for replacement.

Wonders

do you know if replacement tandem pump is a recall.

konigstiger

Possible misunderstanding MB recommends replacing original pump installed at production up to A169441 with revised part. Your VIN is within range for replacement. Not a recall or service campaign but rather DTB recommendation.



Seriously consider replacing fluid – brown “may” be an indication of wrong fluid, should be green for ABC – Pentosin CHF 11S part # 001989240310 (BQ1320001).

Wonders

MB said to wait till steering gets heavy again then bring it in but i will get it booked back in based on color of fluid.

thanks konigstiger you've been a big help and given me lots of points to give MB service.

Wonders

konigstiger can i do power steering fluid flush without touching ABC, is it possible to extract old fluid with a pump from power steering reservoir then add fresh green fluid or does car have to go to MB.

Wonders

konigstiger - Top Man!

Wonders

konigstiger
for last 2 weeks i have been driving car with transmission in sports and steering hasn't gone heavy at all, switched back to comfort mode today and steering immediately went heavy and transmission gearshift was hard, i'm now back in sports mode and car is fine.

Any further thoughts please.

Wonders

found pool of green/brown oil on drive today, no lights on dash yet but expect leak is from tandem pump, suspect pump has been on it's way out for a while now and was causing heavy steering, is leak the next sign of a failed pump.