Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 04-10-2002, 08:40 PM
MikeTangas's Avatar
Senior Member
 
Join Date: Apr 2000
Location: So. Cal
Posts: 4,430
Accumulator question (hydraulic suspension)

My accumulators arrived today, now replaced. Easy 45 minute job, but a little tight on the driver's side - thanks to the exhaust.

Now for my question. Is it possible to determine a blown accumulator, or pair of them, by the appearance of the fluid when bleeding down the system? I ask, because as I was bleeding down the system, prior to cracking open the lines, I attached a clear bleeder hose to the bleeder valve. When I opened the valve, the fluid coming through the hose was sort of a foamy mix, about the color of sea foam - definitely aerated. After a few minutes of bleed down, the air dissapated and the remaining fluid ran clear until it stopped.

The rest was a simple matter of disconnecting the lines, pulling down the cells, swapping the end fittings and replacing the units and connecting the lines. Both cells had a good quantity of fluid inside. In all, I probably lost about 1/2 quart of fluid.

Bleeding down the system before cracking any lines is the only way to go. Minimal mess and no spraying oil.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.
Reply With Quote
  #2  
Old 04-10-2002, 09:18 PM
Registered User
 
Join Date: Jul 2000
Location: Sunny Florida
Posts: 199
I thought I read someplace that the foam out of the bleed screw meant the accumulator had failed. Mine came out the same way, and things got all better when I replaced the accumulators and flushed the lines with new fluid.

If you are not happy with the ride height after replaceing the accumulators, you may wish to check the turnbuckle type adjustment that is on the differential, used to adjust ride height for the rear. Mine had been adjusted all the way to one end, I guess to try to overcome the bad accumulators. I just fiddled with it until I was happy with the rear end height.

And I was not so smart doing mine. Fluid EVERYWHERE and I ended up covered in it, rolling around the garage floor! A fun afternoon anyway, but I would have preferred to do it your way!

Good luck!
__________________
1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)
Reply With Quote
  #3  
Old 04-10-2002, 09:26 PM
MikeTangas's Avatar
Senior Member
 
Join Date: Apr 2000
Location: So. Cal
Posts: 4,430
I hadn't heard, nor read, about foamy fluid meaning bad accumulators, but I figured it would. Since the fluid had recently been changed, for me it was simply plug and play.

It looks like the rear might be setting a bit lower, I measured 16.75 inches from the gound to the lower edge of the "hump" line on the rear bumper after replacement (but failed to take any measurements prior).

I though the ride was good, but now it is REALLY GOOD.
__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.
Reply With Quote
  #4  
Old 04-11-2002, 12:21 AM
Registered User
 
Join Date: Dec 2000
Posts: 368
The cells fail internally, causing the nitrogen to mix with the hydraulic fluid (foamy fluid).

Vin
Reply With Quote
  #5  
Old 04-11-2002, 12:26 AM
MikeTangas's Avatar
Senior Member
 
Join Date: Apr 2000
Location: So. Cal
Posts: 4,430
Thanks Vin.

For posterity: Think you have a bad accumulator, or accumulators? Bleed the suspension fluid at the control vavle, through a clear line. If foamy, replace the cells.

But that brings another question to mind. Why doesn't the aerated fluid purge the air (or in this case nitrogen) as it is constantly pumped through the resevoir.
__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.
Reply With Quote
  #6  
Old 04-11-2002, 10:32 AM
Registered User
 
Join Date: Jun 2000
Location: Plano, TX
Posts: 2,574
I think foamy fluid is normal for these systems. I had to replace the leveling valve on my wagon about a year after replacing the accumulators. You bet the fluid was highly aerated when I opened the bleed valve. There's no provision to bleed the air out of the lines between the leveling valve and the accumulators, so I'd kinda expect it. As well the fluid & air is under high pressure, so when you release it to atmospheric pressure, the trapped air is going to rapidly expand, foaming the hydraulic oil.
Reply With Quote
  #7  
Old 04-11-2002, 07:35 PM
Registered User
 
Join Date: Dec 2000
Posts: 368
Mike,

Keep in mind that fluid only circulates between pump and valve. Once you bleed system properly (after installing new shock or accumulator) only a leaking cell can cause foam.
Reply With Quote
  #8  
Old 06-15-2009, 07:22 PM
Registered User
 
Join Date: Jun 2009
Posts: 2
so does that mean that there is no way or need to try to purge air from reservoir aftr i just changed it on the driver's side?
i have a 300te and the rear drivers side was buggy up and down, though the oil looked fine it was missing a simple copper washer--i dont know now if that was the only problem and I could have saved myself big $$, but here is the question too--the passenger side accumulator is MUCH more difficult to get to than the drives side gottta take a lot of things off it b4 replacing it--why did they mke it so hard on that side and what can i do about it?
thanks for any responses.
Reply With Quote
  #9  
Old 06-15-2009, 09:30 PM
Registered User
 
Join Date: Sep 2002
Location: Allentown, PA
Posts: 482
Accuulators are to be replaced in pairs. Bleeding is usually required at control valve. If you disconnect lines at control valve, be extremely careful so as not to damage threads.
Many posts regarding "accumulators"

vinamg wrote
"Keep in mind that fluid only circulates between pump and valve."
If so, how does foamy fluid get to reservoir? The typical first check for bad accumulator(s). Explain...
Reply With Quote
  #10  
Old 06-15-2009, 10:01 PM
Registered User
 
Join Date: Dec 2006
Location: beautiful Bucks Co, PA
Posts: 961
I encountered foamy fluid when changing the accumulators on my wagon. The bleeder valve was well stuck in the valve body, so I cracked a line at an accumulator an took a shower. The accumulators were shot, as a pencil poked into them would go down well past the top of the sphere.
After all was buttoned up, there seemed to be no need to bleed the system as it worked as the guys back Sindelfingen intended.
Reply With Quote
  #11  
Old 08-04-2009, 11:28 AM
Registered User
 
Join Date: Aug 2009
Posts: 2
Quote:
Originally Posted by MikeTangas View Post
Thanks Vin.

For posterity: Think you have a bad accumulator, or accumulators? Bleed the suspension fluid at the control vavle, through a clear line. If foamy, replace the cells.

But that brings another question to mind. Why doesn't the aerated fluid purge the air (or in this case nitrogen) as it is constantly pumped through the resevoir.
I know how to replace the Air Cells and rear shocks for my 91 560 SEL simply by putting back what I took off! What is the right sequence and order of this repair and how would you bleed the system? I know that the suspension oil is a special oil formulated just for this application; how about the bleeding? Is it just like brake system?

I do appriciate any suggestion that the Forum can provide.

Best Reagds,

Lucciani

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
94 SL600 hydraulic suspension question p-car993 Tech Help 0 02-17-2004 08:06 PM
Right hydraulic oil for self level suspension David-S Diesel Discussion 4 10-26-2003 02:24 PM
W126 Hydraulic Suspension albert champion Tech Help 2 06-11-2003 10:04 PM
Hydraulic Suspension on a 300CE Mike300ce Mercedes-Benz Performance Paddock 5 02-07-2003 02:54 AM
Hydraulic suspension removal Tom16v Tech Help 5 07-26-2000 10:56 AM



All times are GMT -4. The time now is 08:29 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page