I have an E39 that recently developed a squeak that seems related to the suspension of the vehicle. Squeak happens when driving on road with small to large bumps & when pushing down on the right rear bumper. I have removed rear wheel and sprayed anyhing that looked like a likely culprit (all rubber bushings body mounting points and springs/ shocks. WD-40 did not help, nor did oil. I did get some temporary relief from spray silicone but that lasted less than a week. And of course when I applied the silicone I sprayed all of the points mentioned above. Anyone ever diagnose this problem and/or can provide a more permanent solution???
sounds like one of the right upper control arms. you can make a pinhole in the balljoint boot and stick the straw from a wd40 can through,spray a little in, do one at a time and drive over bumps to work the suspension, when the noise goes away, you will know which arm needs changing. sometimes they are dried out and the luing is a fix, others are worn out and the noise will return quickly. You should check for play in both arms and the balljoint in the lower arm while you're back there.
