Sphere longevity

[MercedesMike]

It's almost two years to the day since I got back my '78 6.9 from the repair shop where I had all five spheres replaced. This afternoon while driving home from work, the bounce has returned signaling the demise of one or more of those spheres. Bouncy bouncy is how I would best describe the ride home. Taking a poll of the reading audience: How long have you been able to run before having to replace these spheres? And what diagnostic steps should my repair guy take to diagnose which one or ones have gone bad? The last time this happened, it cost me over $2K in parts and labor to replace them. Not happy.

[John S]

Wow, 2 years is a very short time for a sphere to last, hopefully it is only one sphere that needs replacing.

I had spheres in my 450SEL for 5 years before it was hail damaged and sold, the previous spheres were 5+ years old, probably nearer 10 I should think.

[SEL_69L]

I stand to be corrected, but I think that there 3 manufacturers of spheres for 6.9's. I do not know if there are any differences in quality between the manufacturers. Fichtel & Sachs are one of the manufacturers, but they are not the ones in my car.

[Tony66_au]

Im getting conflicting reports on what signals a buggered sphere.

My wagon's rear end sits high and is as hard as a rock so it skips and bounces but not because of soft suspension but because its as hard as a rock.
Can someone enlighten me please?

Im also told that they had a filter fitted later on to the low pressure return.

[Oversize]

From what I understand the first sign of trouble is uncontrolled movement in the suspension; not sure exactly why. When they've completely failed it'll go rock hard. When the diaphram fails and the nitrogen leaks out, there's nothing but fluid in the cell and a fluid cannot be compressed.
I'd suggest bouncing the car when stationary by pushing down on each corner to try and isolate the failed cell. I'd replace them in pairs (across an axle), like any standard shock absorber so you don't upset the balance of the car. I'd also check the warranty, but it probably expired after only 12 months.

[Tony66_au]

That makes sense, I voiced those same thoughts elsewhere and was told that noooo they had to be soft bouncy when they failed.

New spheres in the TE then......

[Styria]

Hi MercedesMike and others - it is somewhat unusual for the Air Cells to only last for two years. Like with a number of 6.9 components, the supply of 6.9 parts exclusive has been swallowed up by items that used to be later models exclusives, such as Air Cells which are now marketed for both the 560 and 6.9 alongside.

In the olden days, and I am talking of fifteen years ago, a 6.9 Air Cell would in fact provide you with a service life of no less than ten years. Alas, those halcyon days are gone. In my experience, a new 'after-market' Air cell should last about four to five years. For the Australian market, you are normally supplied with units made by Febi-Bilstein, but I understand that Meyles were available probably three to four years ago, and another brand is Lemfoerder. I believe the last named to be the best, but also the most expensive. I do not know who makes the units for MB themselves. Meyle are the least likely to last well.

If an Air Cell has collapsed, that usually, in fact will always, result in a very bouncy, and downright uncomfortable ride. In fact, the ride can become so rigid as to result in the vehicle becoming undriveable and downright dangerous.

A well set up 6.9 should provide you with soft, and floating movement, when placing your weight on the front or rear bumper bars. It should rock like a waterbed. Regards Styria

[mathew]

Originally Posted by Tony66_au

Im getting conflicting reports on what signals a buggered sphere.

My wagon's rear end sits high and is as hard as a rock so it skips and bounces but not because of soft suspension but because its as hard as a rock.
Can someone enlighten me please?

Im also told that they had a filter fitted later on to the low pressure return.

I believe that indicates the rear has been set far to high, easily done when servicing the system. There is a lever that needs to be operated when filling the reseveror and a lot of people fill the system not realising they have raised the car to high. Drain and reset the level DO NOT ADJUST THE LENGTH OF THE LEVER/ROD UNDER ANY CIRCUMSTANCE!

Cheers Mat

[Oversize]

Do we have the part numbers for the cells??

[Oversize]

I found a lead on the front ones:

http://cgi.ebay.com.au/ws/eBayISAPI....m=200800786322

[aussie 6.9]

I brought my car about 97 with 180000k on it.Around 2001 I replaced all the speres and all is good up till now where it has done about 260000k.Regards Aussie 6.9

[Styria]

Mark, you have had an exceptional life span from your Air Cells. I tend to think, and I am confident in stating so, what you bought in 2001 is no longer available today. I can take my mind back to when the cells were originally replaced when I first bought Gleaming Beauty - I had a longevity span of about ten years. Are you now starting to need new ones ? Just as a matter of interest.

It would be of great interest also, to me anyway, what you think of 6.9 ownership. Your likes and dislikes, reliability and/or lack thereof etc. etc. If you can make the time........ Regards Styria

[Michel]

Originally Posted by Styria

Mark, you have had an exceptional life span from your Air Cells. I tend to think, and I am confident in stating so, what you bought in 2001 is no longer available today. I can take my mind back to when the cells were originally replaced when I first bought Gleaming Beauty - I had a longevity span of about ten years. Are you now starting to need new ones ? Just as a matter of interest.

It would be of great interest also, to me anyway, what you think of 6.9 ownership. Your likes and dislikes, reliability and/or lack thereof etc. etc. If you can make the time........ Regards Styria

Mine have been changed eight years ago and still feel terrific.

[motec 6.9]

Hi Michel all 5 off mine were done in 2011. I was just concerned about fluid leaking out of the reservoir when car was lowered will not know till I get to drive it I guess.

[Oversize]

Whatever happened to Mike?