X5 PROBLEM(Knocking sound)

[FunfDreisig]

Originally Posted by grey

you've given us a lot of valuable info hear, thanks heaps. I might remove the wheels and have a look at the stabilizer bar bushings myself. BTW, have you got any photos?

Sorry I didn't take photos when I fixed the E53 because I was at a dealer tech session on their lift. I wanted to free up the lift ASAP for others to use.

When the front wheels of the X5 are level, the stabilizer bar is not under much (if any) tension. It doesn't really matter whether they are on the ground supporting the X5 or hanging down while on a lift -- as long as both front wheels are the same. You do NOT need to take off any wheels to inspect/replace the rubber bushings on an E53. And I suspect you don't need to do it on an E70 wo/ the active stabilizer* either. But you do need to be able to roll around under the edge of the vehicle to reach the mounts. I was able to unbolt the mounts and reinstall them with no problems with the E53 X5 sitting on my home made wooden "ramps" that raise the X5 a whooping 3 inches. But it really helped to have the X5 up in the air on a 2 post lift while I scraped the grunge off the bar.

Fund Dreisig

p.s. my "ramps" are simply staggered 2x12 cut with a 45 degree lip and screwed together. See my DIY 35d oil change thread for a pic. of these magnificent hand crafted beauties

* I don't have any knowledge of how to work on an X5 with an active stabilizer and never will.

[dbox]

mine makes a noise very similar to an M5 with a lighter flywheel installed. it doesn't happen all of the time but does worry me.

[FunfDreisig]

I just looked under my E70 35d and I think it is much less likely for an E70 to have the same problems as our E53 did. The E70 stabilizer bar mounts are NOT close to the stiffening plate. And the E70 stabilizer bar, and more importantly the mounts, are behind a plastic splash cover which should keep them form getting grunged up. Note: the E53 bar and mounts are completely exposed.

So if my X5 was already out of warranty, my first line of attack on an E70 would be to look very carefully at all of the hard rubber bushings in the lower control arms. These are pretty exposed and easily visible with the wheel off. I'd jack up the front end. Put it on HD jack stands. Remove both front wheels and use a long bar to gently lever on each end of the lower suspension pieces to see if the bushing gives or is cracked. FWIW this is what the BMW tech did when we first put our E53 up on the 2 post lift during the tech session. After he didn't find any problems. I told him I wanted to pull down the stabilizer bar and check the bushings becuse I had a hunch* this was were the problem was. He was shocked at the condition of the bar/bushings.

Funf Dreisig

* BTW this was not a brilliant bit of diagnosis. BMW had already replaced most of the front suspension during multiple UNSUCCESSFUL attempts to cure the snapping sound. The mounts for the stabilizer were almost the only thing left that they hadn't replaced.