2004 Mercedes-Benz ML350 Power Steering Pump

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wavinwayne

wavinwayne

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Good thing I just landed a little bit of work, because I'm going to need the money. My wife's ML350 started making a terrible whine over the weekend that sounded like a failed/failing power steering pump. I checked the fluid reservoir and the fluid was at the proper level. Nevertheless, I took the Mercedes to my mechanic this morning, and he just called and said the power steering pump was bad. GRRRRRRRR!!!! Around $350 to replace the pump and to install a new accessory drive belt. Could be worse, I suppose.
 
Doesn't sound bad at all. I think I remember paying $400 or more to have the Dodge dealer replace the power steering pump in our old 2003 Grand Caravan. It was at the very back of the transverse accessory drive, so I'm sure it was a pistol to replace.
 
Originally Posted By: wavinwayne
My wife's ML350 started making a terrible whine over the weekend that sounded like a failed/failing power steering pump. I checked the fluid reservoir and the fluid was at the proper level.

Did you ever change the PSF ? My 2000 E430 made a loud whine when turning the steering wheel in either direction about 2 years ago, I changed PSF with 1 quart Maxlife with turkey baster several times over 2-3 weeks. It fixed the whine and so far so good.
 
wavinwayne,

Obviously a newer machine than my 1995 E320, so please consider all of the following FYI, subject to verification with your own research:
  • You didn't mention mileage, but had the power steering fluid ever been changed? My E-Class Owner's Bible says - Mercedes-Benz service recommendations do not include changing the power steering fluid or filter. However, experience over a 30 year period has shown that fresh fluid keeps the power steering pump and gear in better condition. It is sufficient to change the fluid in the power steering reservoir every 15,000 mile maintenance service and the filter every 60,000 miles...

  • If it was serviced, do you know if ATF was used for the refill? The discussion on the Benzworld.org forums had stories of people using ATF and then getting abnormal pump wear (resulting in a squealing pump). It was enough to convince me to use purpose-made power steering fluid when I changed the opaque, black fluid I found in mine.

  • FWIW, I think there are pump rebuild kits that address at least some of the failure modes on some pump models. If you have the tools and inclination, you could do a rebuild on the old part and keep it on the shelf against future need.

Sorry for the pain. At least it wasn't the steering gearbox, I think that part is $800+, and undoubtedly even more labor cost than the pump.
 
Originally Posted By: AMRoberts
wavinwayne,

Obviously a newer machine than my 1995 E320, so please consider all of the following FYI, subject to verification with your own research:
  • You didn't mention mileage, but had the power steering fluid ever been changed? My E-Class Owner's Bible says - Mercedes-Benz service recommendations do not include changing the power steering fluid or filter. However, experience over a 30 year period has shown that fresh fluid keeps the power steering pump and gear in better condition. It is sufficient to change the fluid in the power steering reservoir every 15,000 mile maintenance service and the filter every 60,000 miles...

  • If it was serviced, do you know if ATF was used for the refill? The discussion on the Benzworld.org forums had stories of people using ATF and then getting abnormal pump wear (resulting in a squealing pump). It was enough to convince me to use purpose-made power steering fluid when I changed the opaque, black fluid I found in mine.

  • FWIW, I think there are pump rebuild kits that address at least some of the failure modes on some pump models. If you have the tools and inclination, you could do a rebuild on the old part and keep it on the shelf against future need.

Sorry for the pain. At least it wasn't the steering gearbox, I think that part is $800+, and undoubtedly even more labor cost than the pump.


The fluid has never been changed. I topped it up a couple years back because it was a tad low. I used the fluid from the M-B dealer. Oh well, I guess these things happen sometimes.

My wife and I are considering getting rid of the ML and getting another Expedition, since the ML is a little too small for our family when we travel. The gas mileage in the ML is awful, too.
 
Had to wait a day for the new PS pump to be delivered; the ML is still in the shop. Should be ready by lunch tomorrow..

I hate repairs.
 
Originally Posted By: LT4 Vette
$350 ain't bad considering its a Benz


True. This vehicle isn't overly complex, though; I guess that's a good thing.
 
Is it a remanufactured unit,new, or rebuilt by the mechanic? Had a P/S pump rebuilt. It lasted less than a year and started leaking again. How much is the core? I just paid the core charge of $25 or something like that. So, if it happens again. I could rebuild it myself. The rebuild kit was like $20 but, the remenaufactured one is around $250. How is the warranty? You can usually tell what you have with the warranty. I guess labor for your model is easy b/c the book time for 92 400E for R&R of the P/S pump is 12hrs.Labor only.
 
Originally Posted By: wavinwayne
Good thing I just landed a little bit of work, because I'm going to need the money. My wife's ML350 started making a terrible whine over the weekend that sounded like a failed/failing power steering pump. I checked the fluid reservoir and the fluid was at the proper level. Nevertheless, I took the Mercedes to my mechanic this morning, and he just called and said the power steering pump was bad. GRRRRRRRR!!!! Around $350 to replace the pump and to install a new accessory drive belt. Could be worse, I suppose.



Mercedes usually uses a power steering filter. I hope you didnt get hosed.
 
Originally Posted By: ludey
How is the warranty? You can usually tell what you have with the warranty. I guess labor for your model is easy b/c the book time for 92 400E for R&R of the P/S pump is 12hrs.Labor only.


How can a p/s pump R&R takes 12 hours? Did they have to lift the engine/transmission out to get to the pump?
 
I have no idea but, I know of three different shops past on the idea of removing and replacing and said. Topping it off ever so often would be more economical. All three did not want to take the job basically. The person who did it. It took him three weeks to a month but, he did it on his time off after the shop closed.
 
UPDATE:

Turns out the power steering pump on the ML was NOT the issue. The whine is still there when the vehicle warms up, just as before. Taking it back to the shop on Friday morning. NOT HAPPY!!!
 
UPDATE TO EARLIER UPDATE:

Long story short: I was going on bad information given to me over the phone by my wife. As it turns out, the new PS pump DID fix the whining noise. No return trip to the shop, at least not for this problem.
 
AHHHHH, the Mercedes just doesn't want to behave. I had to take it back to the shop today, after discovering a puddle of PSF under it this morning. A new O-ring between the reservoir and the pump seems to have fixed it. TBC....
 
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