Hi, i have owned a w211 2005 280 CDi estate for the last 10 years, now has 155,000 miles on the clock. My R/O/S suspension keeps lowering overnight, I assumed it was a faulty air bag and have replaced with a 2nd hand unit. When my mechanic removed the old air bag he thought it appeared to be fine, and there were no apparent leaks in the system. Unfortunately the replacement air bag is doing the same thing. The compressor is inflating the air bag after a coupe of minutes and its fine until left for a few hours when it then deflates again. Are the rear air bags linked , i.e could the R/N/S bag be the problem, or it is ikey to be the air lines/sensor etc ? Has anyone got any ideas/solutions. Thanks

Used replacement could have internal leak as might have been the case with original. Attachments cover line distribution and leak detection.

are the air bags interchangeable from side to side or are they dedicated O/S & N/S , Thanks

Yes.

Inflate the suspension and check all the connection points with soapy water. You can convert it to coil springs pretty easily with used rear springs and lower control arms from a sedan.