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
