Hi everyone,

I’m really hoping to get some expert guidance here as I’m stuck and don’t want to make another expensive mistake.

Vehicle Details

• 2002 Mercedes-Benz S55 AMG
• While back i had oil leak from hydraulic suspension, so i had that removed and ABC disabled

Issue / Symptoms

• Started noticing a crackling / whining noise from the engine bay, especially when turning the wheel
• Noise increases with steering input (low-speed maneuvers / parking)
• Steering still functions, but noise is getting worse

What I’ve done so far

• Took the car to Pep Boys → diagnosed as failing power steering pump
• They recommended replacing the pump and sourcing from BuyAutoParts

My Concern

This is where I’m confused and honestly frustrated:

1. I’ve already replaced this pump TWICE before (from BuyAutoParts), and both went bad
2. Labor to replace is ~$1000, so I want to get this right this time
3. I went to Advance Auto Parts, and they provided a pump that appears to be incorrect (with out the sensor)

Advance Auto Part Details

From the part they handed me:

• Brand: CarQuest Premium
• Part #: 990-0654CQ
• Type: Remanufactured power steering pump

This unit appears to be a different configuration (possibly with sensor / different housing) and did not match what I expected for this car.

Main Confusion: Sensor vs No Sensor

• Advance Auto told me I need a pump WITH a sensor
• Pep Boys / others are pointing to standard pumps
• BuyAutoParts sells reman unit 86-00770R, which seems to be commonly referenced

Part Numbers I’m Seeing

From my research, I’m seeing conflicting info:

• 86-00770R (BuyAutoParts – remanufactured)

Some listings mention:

• “with sensor”
• others show no electrical connector at all

My Questions

1. Does the 2002 S55 AMG actually use a power steering pump WITH a sensor?
   Or is the sensor located elsewhere (rack / pressure line)?
2. Is 86-00770R the correct part for this car?
   (or is there a better OEM / aftermarket option?)
3. Has anyone experienced repeat failures with reman pumps from BuyAutoParts?
   → If yes, what brand/vendor would you recommend instead?
4. Would you recommend:
   • OEM Mercedes pump (if still available)?
   • Rebuild my original pump instead?
   • Specific brand (LUK, Bosch, etc.)?
5. Anything else I should check before replacing again?
   • Reservoir?
   • Lines?
   • Fluid contamination / flushing system?

My Situation

At this point:

• I don’t want to spend another $1000 in labor + part and have it fail again
• I want to make sure I’m buying the correct configuration (sensor vs no sensor)

Where I’m Currently Looking

• BuyAutoParts (reman unit 86-00770R)
• Advance Auto Parts (CarQuest 990-0654CQ, but seems incorrect)

Would really appreciate guidance from anyone who has worked on S55 AMG steering systems or replaced this pump before.

Thanks in advance — this forum has already been a huge help.

 

One is left to assume you've already done the coil-over swap, correct? I'm not one who'll be able to help you but wanted to clear that up. Good luck.
Did however come across this: Power Steering Pump w/Bracket Mercedes Benz SL CL S-Class Coilover Conversion | Gold Element Autowor

 

OP is the DUO-Pump still in place or did you replace the pump that does ABC and Power steering with the pump that just does power steering?

Hint: You are shopping for parts at the wrong stores!

 

God knows that's the truth!

 

Your confusion and frustration journey started when you decided to remove the factory suspension for a subpar solution without properly researching. Had you researched, you would have fixed the ABC properly, saved money, and been done with the entire situation.

All you need is a standard s430/500 power steering pump. Link below;

​​​​​​https://www.ebay.com/itm/39276092179...kaAn_ZEALw_wcB

If the ABC components were removed properly, you will also need to ring a professional that can code out the ABC error messages so the vehicle doesn't still think the ABC is active. There is no sensor needed for a standard PS Pump, you either have it or you don't. You can let your hands figure that one out.

I can see why the long time owners of these cars get frustrated at the common questions/problems with the ABC, however i must remember i too was a newbie and you all have helped very much, so i try to pay it forward.

Ironically, I'm still having ABC issues myself, however my car has been on jack-stands for 4 months replacing the Harmonic balancer

Good luck

- Joe

 

Pray tell Joe... How does it take four months to do a harmonic balancer.

 

It gets cold in the NE, along with work and no motivation to dig into it. Too much salt on the road so it doesn't get driven much in the winter. Blew the HB Apart sometime in October and parked it. Found a brand new HB pop up on FB Marketplace and scooped it, now just finding time to get around to it. It'l be ready in a few weeks, along with some other maintenance items i have to check off the list and some fun parts.

- Joe

 

I sent the PO a private message suggesting he check out the responses to his post and here is his reply
"I did. and i am not sure if its applicable to my merc. I need one with sensor not sure how to interpret "coil over" comment. any suggestion? i have no choice but to order from buyautoparts.com as they seem to be the only ones selling refurbished power steering pump."

 

Oh... That fourth season. That is my favorite time to work on the cars in Arizona.