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X5 PROBLEM(Knocking sound)

Hi all X5 fans,

i have a 2007 X5 E70 with sports package,
i am having this problem for a while. when i backout of my garage, while turning my can towards left. i can hear some 'knocking sound" coming out of the front undercarriage, sound like from the front wheels area or suspension.

i took it to the BMW service center for like 5 times. frist few times.. the advisior told me dat they can t hear anything..everytime i left the car there for e whole day..till last time ..they get their Head person in charge to test drive with me.. then he heard the noise..
i was told that sometime losen..and they fixed it.
when i drove home..the problem is still there

anyone has similar problem ??

i have a very intermittent noise coming from the front right wheel.
its extremely rare. its a noise like something is out of place and it quickly settles in.

Quote:

Originally Posted by xrwrx (Post 687052)

....
i am having this problem for a while. when i backout of my garage, while turning my can towards left. i can hear some 'knocking sound" coming out of the front undercarriage, sound like from the front wheels area or suspension.....
anyone has similar problem ??

Does this only happen at low speed on uneven terrain? Is the knocking sound only a few 'irregular knocks' or is it several more 'rhythmic knocks'?

FWIW BMW techs are paid to replace obviously broken stuff quickly, not diagnose intermittent problems.

Funf Dreisig

intermittent problems are tough.... keep at it and keep us udated. Thanks!

I had an intermittent creak or knock with my 4.8is. Turned out to be something with suspension that had to be replaced. They didn't think anything was wrong when I told them, but they did find it the first time.

Quote:

Originally Posted by FunfDreisig (Post 687388)

mine only comes in uneven terrain, low speed only, and is irregular. The noise only comes from front right side wheel. FunfDreisig, is this a known thing? what do you think it is? its very intermittent but it exists.

Quote:

Originally Posted by grey (Post 687733)

I'm not sure about the E70 but we had a similar problem with our 2001 E53 that drove me nuts until I finally diagnosed and fixed it. If my X5 was still under warranty I would take it in to have the dealer do a thorough front end check for any worn/broken components. AND I would require them to remove/check the rubber frame mounts for the stabilizer bar, even if it meant I had to pay to have new rubber bushings installed in the 2 mounts. They don't cost much and it wouldn't hurt to have new ones anyway :)

Details:
One quirk of the X5 front end design is the large, flat, thick aluminum Stiffening Plate under the engine and the location of the front end Stabilizer bar (AKA roll bar). In the E53 the bolts that attach the stabilizer bar are the same bolts that attach the rear of the Stiffening Plate to the frame. This means that any noise created by the stabilizer bar is amplified by the stiffening plate/frame. Essestially the Stiffening plate acts as a speaker/megaphone making the sound louder. In the E70 the stabilizer goes in front of the engine; but I suspect the mounts are still close enough to the front of this large aluminum plate to allow the plate to amplify the sound.

In our E53 the stabilizer bar became crusted with road grime that built up between the bar and the rubber bushing in the mount. The grime was very rough and so crusty that it required a utility knife to scrape off the bar. This crusted on grime caused the stabilizer bar to 'grab' the rubber bushing and twist it inside the metal mount holder. After a little more twisting the rubber mount would slip back into place with a snap that was amplified by the stiffening plate.

This snapping can be forced to happen by driving very slowly over uneven surfaces in a gentle turn to get the stabilizer bar to twist. For example when pulling into or backing out of a garage or parking space where there is a 1-2" lip. Or simply over an irregular road surface. The trick to making it 'snap' is the get one front wheel higher/lower than the other three wheels at very low speeds so the stailizer bar has time to twist and release the rubber bushing in one large snap. If you go too fast, it still snaps but the snaps are much quicker and quieter. Think San Andreas Fault. You're going for the big one :yikes:

Funf Dreisig

Quote:

Originally Posted by FunfDreisig (Post 687388)

It does happen when in low speed when over uneven road, the sound is more like rhythmic.

i send the car in again today, i took it to the Service Manager this time, he took a test drive with me. and he heard the noise right away.......
My X5 are having Malfuction with the hardbrake 2nd times...

Quote:

Originally Posted by FunfDreisig (Post 687750)

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?

Quote:

Originally Posted by grey (Post 688193)

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 :rolleyes:

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

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.

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.:(