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.

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)

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.

The cells fail internally, causing the nitrogen to mix with the hydraulic fluid (foamy fluid).

Vin

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.

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.

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.

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.

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...

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.

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