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2000 ML55 (My first Benz)
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82 Posts
Discussion Starter #1
I'm in Wisconsin and I've noticed as it gets cooler outside I hear a loud whine when I turn the wheel when I first start the car and drive it, . The colder it is the louder the whine. However, if I let the car warm up completely, it goes away. The power steering fluid is full.

Any ideas?
 

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2000 ML430 SOLD, 2007 BMW 328i Coupe, 2014 BMW i3, 2019 Honda Odyssey
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2,982 Posts
That makes three of us... It is really cold compared to what I usually drive in.
 

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2004 ml500
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166 Posts
Powersteering fluild needs to be replaced, maybe?
I have it in my other car Toyota Camrey and plan to change the fluid over the weekend,
 

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99 White ML320, 13 Audi S5,84 300ZX Turbo, 03 Audi A4, 03 Audi TT, 65 Ford Galaxie Conv
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474 Posts
Seems to make sense to me that the dreaded diaphragm in the reservoir in combination with the higher viscous fluid becuase of the cold weather. I would lean this way. Anyone else?
 

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1990 Unimog 1300L, 2004 ML350, 1999 SLK 230,
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579 Posts
I don't have an answer yet, but I have the same problem.
 

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2001 Mercedes ML
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14 Posts
I'm having the same problem I had no problem prior to the cold weather. are you saying to change your fluid ? or the Idle pulley ?
 

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1990 Unimog 1300L, 2004 ML350, 1999 SLK 230,
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579 Posts
I used to have this problem when it got real cold, but the whining would go away after a couple of minutes until a couple of days ago when it stayed. It got worse every time I turned the wheel. Today I bought some new Benz power steering oil and topped off the reservoir and all is quiet again.
I believe when it's real cold, the oil is so stiff that perhaps the pump cavitates a bit, hence the noise. If it was the idler pulley, I would think it would make the same noise all the time, no matter whether you're turning the wheel or not.
I could be wrong though.
In any case, make sure the oil level is right up before you do anything else. Don't forget you can't use just any power steering fluid. It must be the Benz stuff, because of compatibility problems, so I'm told.
 

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1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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Gee - I love the one response "I checked the level of my fluid" - that is a viable clue to check out. I think a owner would like to rule put the mechanical part first, before intellectually extrapolating the thermophysical characteristics of MB power steering fluid

I like the comment from Orange CA, yes a failing belt tensioner or idler "pulley" also will actup more when cold, good point from a somewhat warmer region.

Keep the faith !
 

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2004 ml500
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166 Posts
I belive the PS liquid to be hydroscopic and loose its potential over time...absorbing moisture in air.
 

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2001 Mercedes-Benz ML320
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27 Posts
My mechanic told me this is very normal with mercedes. However, after I got an oil change, it went away. Weird?
 

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W163 ML500 2003
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120 Posts
My mechanic told me this is very normal with mercedes. /QUOTE]

umm, no its not. lol. why would anyone buy a mercedes if its normal to be noisy?! Just think about it..

mine was the o-ring behind the reservoir. no more noise.

What he might have meant (your mechanic), is that its normal for that noise to appear due to a mechanical problem. But its not 'normal' in any way.
 

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2000 ML55 (My first Benz)
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82 Posts
Discussion Starter #14
Thanks everyone for the info. The answer to the question was my power steering fluid was almost gone due to a leak in the pump. It was one of the first things I checked when I first heard the sound, but because of the leak, it went down shortly after I checked it. I topped it off and the sound went away. So add a new pump to my list of Benz to-do's. No biggie....
 

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1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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7,035 Posts
Please understand that sometimes a reservoir o-ring seepage is mistaken for a pump leak, so best to re-check.

About the only way I have seen pumps develop leaks is after major air has been in the system.

Before you go to change out your pump; check with MB dealer with your VIN to see if there are any outstanding campaigns not done on your ML power steering hoses, which are one major source of air leakage into the system. Those campaigns also take care of other issues gratis if the cause is air leakage from the undone hose updates; check to see if the o-ring, not the pump, is the source of the fluid leakage: understand if you replace your ZF pump (around $300 for ZF quality rebuilt) you will also need to replace the reservoir ($35) and new o-ring ($2) and use MB fluid; any work with the ML understand the correct bleeding procedure.

If the o-ring is causing the leakage you see, replace the reservoir as well but MUST follow the correct bleeding procedure or you will be back at square 1.

Keep the faith !
 

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1999 ML320 and 2009 E350
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98 Posts
Please understand that sometimes a reservoir o-ring seepage is mistaken for a pump leak, so best to re-check.

About the only way I have seen pumps develop leaks is after major air has been in the system.

Before you go to change out your pump; check with MB dealer with your VIN to see if there are any outstanding campaigns not done on your ML power steering hoses, which are one major source of air leakage into the system. Those campaigns also take care of other issues gratis if the cause is air leakage from the undone hose updates; check to see if the o-ring, not the pump, is the source of the fluid leakage: understand if you replace your ZF pump (around $300 for ZF quality rebuilt) you will also need to replace the reservoir ($35) and new o-ring ($2) and use MB fluid; any work with the ML understand the correct bleeding procedure.

If the o-ring is causing the leakage you see, replace the reservoir as well but MUST follow the correct bleeding procedure or you will be back at square 1.

Keep the faith !
I have the same noise but no leak. Two weeks back I decided to change the reservoir and the o-ring, fill the fluid and turn the steering all the way to left and right 20 times ( Do not start the engine until you do this) make sure the fluid lid is open, this clear all the air out of the pump, now no more noise . Don't forget to close the cap before you start the ML
 

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power steering noise

I'm in Wisconsin and I've noticed as it gets cooler outside I hear a loud whine when I turn the wheel when I first start the car and drive it, . The colder it is the louder the whine. However, if I let the car warm up completely, it goes away. The power steering fluid is full.

Any ideas?
take off the revevoir cap and start vehicle see if power steering has any turbulance if it does you may need to chage the power steering pump resevoir,the resevoir has a filter in it that becomes clogged and causes noise in the power steering.
 

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W163 ML500 2003
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120 Posts
take off the revevoir cap and start vehicle see if power steering has any turbulance if it does you may need to chage the power steering pump resevoir,the resevoir has a filter in it that becomes clogged and causes noise in the power steering.
before changing the reservoir he should try and get rid of any air trapped. instructions are all over this forum. Secondly, I'd add lubrizol, if noise comes back after 1 week, then change the O-ring, C-bracket, make sure to follow teh correct bleeding procedure again. If that didn't fix it, get a new reservoir I guess.

basically what fabbrisd1 said.

The reservoir should be the last thing to change.
 

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02 ML 55 (SOLD: 98 & 02 ML320)
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1,309 Posts
take off the revevoir cap and start vehicle see if power steering has any turbulance if it does you may need to chage the power steering pump resevoir,the resevoir has a filter in it that becomes clogged and causes noise in the power steering.
Current Symptoms: Noise/squale/whine when turning and slight vibration in steering wheel.

opened the power steering res. cap and started engine. I observed a heavy gargling turbluence.

does the gargling/turbulence indicate a broken resorvoir or simly that air is present in the system?

I will try to bleed and get the air out as per 43sqd's posted manual ....is it a good idea to add the lubrizol preventatively?


thanks! - phil
 
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