2000 ML55 AMG, 165k miles, well loved truck

Last night I was coming home and felt a little hesitation as I turned from the steering wheel, and noticed a groaning noise as I slowed down and/or turned. I thought "oh great power steering pump" knowing that the dealer told me that they recommend last fall that I replace the pump. Not one to through money at parts when many times something simple is the problem I declined to replace it at the time.

I limped home with only 3 turns (straight drive until my neighborhood), when I got home I looked for any obvious leaks (i.e. hose recall, puddles, etc). Opened up the reservoir and of course had bubbles/foam. The fluid was a little low, so I topped it off (I had MB Steer Gear Fluid at home) and started the truck and turned the wheels lock to lock, noise gone.

I know this isn't a fix, just need to buy time to get parts/or go to the shop. This morning, same problem, I stopped before leaving my neighborhood and topped the fluid off and got almost to work (10 miles) before the noise reappeared.

The truck has had the recall done to the hose, the hose looks good. My buddy/MB mechanic (now gone) a couple years ago replaced the o-ring between the reservoir and the pump.

I've searched the forum and it seems like a lot of the time it may be something simple (i.e. hose, reservoir, o-ring) and was wondering how common is it for the pump to go bad? I'll get to spend more time looking at things tonight.

To recap noise is worse when slowing down (don't have to be turning) or when turning more than 30º (i.e. left or right turns at a stop).

Thanks,
Shaun

Hi there,

You have to change the 0-ring AND the reservoir. Re-fill the reservoir, lift up the front wheels, and turn the steering wheel all the way left and right about 30 times before starting the engine. Then re-fill to proper level.

There are several detailed procedures written up. You can search for it.

Your pump should be OK.

Hope this help.

Rene

__________________
'99 ML320, '00 C280

Thanks Rene.

Unfortunately, I see more fluid under the vehicle and it appears that it coming from under the passenger side boot on the rack. Both boots are torn where they meet the tierod end too. So I'm afraid I have a bad rack.

I will take it to the shop tomorrow to have it inspected further and see if the fluid is migrating. I hope that is the case, but I don't think so.

Any idea what the book time is for a R&R of the rack? Any suggestions on a rack source...I've e-mailed Phil, but I'm afraid it will be quite expensive. Is this the same rack in all the W163 chassis for MY 2000?