ML430 heavy power steering at low engine/road speed - Page 2 - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
post #11 of 16 (permalink) Old 02-17-2018, 11:56 AM
BenzWorld Veteran
 
Date registered: Nov 2014
Vehicle: 2000 E 320 Wagon + 2002 ML 500 SUV
Location: Pineywoods Region of East Texas
Posts: 744
Mentioned: 1 Post(s)
Quoted: 170 Post(s)
I discovered something as regards the power steering fluid / changing fluid: you can suck the reservoir totally dry - (on our 02 ML500 the total amount that can be sucked out at one time is approx 10 ounces - the total system spec says it's 36 ounces total).

So, each 'suck dry' on the reservoir will be almost 1/3 total volume. Plus there is no need to bleed (as Art suggested) - this is undoubtedly because the section below the main reservoir still have sufficient fluid in them to prevent air from actually entering the pump itself.

This is how I've been doing a flush - just sucking dry the reservoir & filling with new. I think I'm on my 4th time. I will do it 6 times & call it done.

Using Prestone Euro Spec Fluid, btw.

As of the 4x, it doesn't look like the 'dirty dark coffee' anymore !

Cheers - David in E Texas



Sent from my RCT6K03W13 using Tapatalk
2000 E 320 White Wagon is offline  
Sponsored Links
Advertisement
 
post #12 of 16 (permalink) Old 02-27-2018, 05:52 PM Thread Starter
BenzWorld Member
 
Date registered: Dec 2011
Vehicle: 2000 ML 430. 2007 Landrover D3 3.9L. 1976 Bristol 411
Location: Melbourne, Australia
Posts: 119
Mentioned: 0 Post(s)
Quoted: 27 Post(s)
(Thread Starter)
Have replaced the rubber low pressure return hose to the radiator - it was in a poor state, the rubber was very soft/perished. Replaced fluid and bled the system. No change unfortunately - steering still very heavy when hot at idle speed (just over 600 rpm) - it's fine when the engine is cold/cool. Even when hot, it's fine over 800-1000 RPM.

Running out of things to replace now - there's really only the high pressure hose and the rack left - assuming the new pump is okay. There is no sign of PS fluid leakage on the rack, or anywhere else.

This is driving me mad.
nivekau is offline  
post #13 of 16 (permalink) Old 02-28-2018, 03:35 PM
BenzWorld Elite
 
Witek_M's Avatar
 
Date registered: Sep 2008
Vehicle: 1972
Location: Dallas, Texas
Posts: 6,474
Mentioned: 20 Post(s)
Quoted: 916 Post(s)
Quote:
Originally Posted by nivekau View Post
Have replaced the rubber low pressure return hose to the radiator - it was in a poor state, the rubber was very soft/perished. Replaced fluid and bled the system. No change unfortunately - steering still very heavy when hot at idle speed (just over 600 rpm) - it's fine when the engine is cold/cool. Even when hot, it's fine over 800-1000 RPM.

Running out of things to replace now - there's really only the high pressure hose and the rack left - assuming the new pump is okay. There is no sign of PS fluid leakage on the rack, or anywhere else.

This is driving me mad.
You need to find someone with MB pressure tester. And check available pressure. To me problem sounds like weak pump. There is nothing in the rack that is temperature dependent.
Attached Files
File Type: pdf PS_pressure.pdf (167.5 KB, 13 views)
Witek_M is offline  
Sponsored Links
Advertisement
 
post #14 of 16 (permalink) Old 03-02-2018, 09:08 AM
Purple Moderator
 
Date registered: Jul 2005
Vehicle: 99 ML430, 00 ML320, 05 E500 4matic Wagon
Location: WI
Posts: 21,597
Mentioned: 35 Post(s)
Quoted: 1527 Post(s)
Lifetime Premium Member
I am suspecting that pump also. That eBay seller is just an order taker from an apartment in the Bronx. The parts are then drop shipped.

Jim has posted warnings about their parts in the past.
Noodles is offline  
post #15 of 16 (permalink) Old 03-12-2018, 05:31 PM Thread Starter
BenzWorld Member
 
Date registered: Dec 2011
Vehicle: 2000 ML 430. 2007 Landrover D3 3.9L. 1976 Bristol 411
Location: Melbourne, Australia
Posts: 119
Mentioned: 0 Post(s)
Quoted: 27 Post(s)
(Thread Starter)
Thumbs up Problem solved!

Quote:
Originally Posted by Witek_M View Post
To me problem sounds like weak pump. There is nothing in the rack that is temperature dependent.
You were right about the pump!

I decided to just bite the bullet and change the pump, except this time I'm confident it is a genuine OEM pump - see photos attached. It came in ZF packaging but appears to have been made by Bosch - as both the pump and the box also had Bosch labelling and it came with Bosch paperwork. It came with a new reservoir and seal also. Cost AUD$440 + Postage.

I am delighted to say that it works! My ML has had a reprieve, because if it hadn't worked it would have been the end of the road!

The fitting process should have been straighforward, given I had done the job before, but I was thwarted by the flare nut where the high pressure hose goes into the pump - when I went to undo it, the whole lug that it screws into in the pump body turned. So I spent a fortune buying a 27mm spanner to fit the lug that screws into the pump body, and I bought a 17mm flare nut spanner. Trouble is there wasn't enough space to get both spanners on the nuts side by side, so I had to grind down the faces of my brand new (expensive) spanners so they would fit side by side. To my horror the edges of the flare nut started to round off rather than the nut moving. I applied WD40 to it, heated it, then cooled it and I still couldn't get it undone. In the end I managed to undo the flare nut using and adjustable vise grip. I thought I was going to have to remove the pump with the high pressure hose attached, which would have been a nightmare job.

I learned a lesson. Be wary of cheap, non-OEM critical parts (my previous replacement pump cost US$100 and turned out to be useless).
Attached Thumbnails
Click image for larger version

Name:	PS Pump Bosch.jpg
Views:	77
Size:	133.5 KB
ID:	2394762  
Attached Images
 
Noodles likes this.
nivekau is offline  
post #16 of 16 (permalink) Old 03-12-2018, 07:28 PM
BenzWorld Elite
 
Witek_M's Avatar
 
Date registered: Sep 2008
Vehicle: 1972
Location: Dallas, Texas
Posts: 6,474
Mentioned: 20 Post(s)
Quoted: 916 Post(s)
Thanks for posting the fix.

Pump in your pix is standard ZF pump. Any other labels are just from parts peddlers.

These days it is hard to determine who owns what and who blows who.
Noodles likes this.
Witek_M is offline  
Sponsored Links
Advertisement
 
Reply

  Mercedes-Benz Forum > Mercedes-Benz Vans/Trucks/SUV/Others > W163 M-Class

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 

Title goes here

close
video goes here
description goes here. Read Full Story
For the best viewing experience please update your browser to Google Chrome