2008 535xi with Front End Noise on Smaller Bumps
 

Hello!

I am a newer owner of a 535xi! Love it so far! I live up in Easter Canada and the roads here can get pretty nasty. Anyway, the car started developing some noise in the front end. When I go over smaller bumps, like especially when it's a patch of a few bumps in a row the front left and now right side seems to make some knocking noises.

So I thought.. must be the control arms, ball joints, etc. However, took it into my mechanic (who specialize in European vehicles) and they said they couldn't find anything wrong.

So I took it to another place who also deal with imports like that and they told me it needed control arm bushings. They replaced the front lower control arms and ball joints.

So I pick it up and drive away... and it never fixed anything. Still have this knocking over the smaller bumps in the road at lower speed.

The car seems to hit hard when it hits a bump and so I wondered about struts (they probably need replaced anyway) but I doubt this is the issue.

Anyone have any advice as to what to look for now. 2 dealers and neither can figure out what's wrong.

The lower control arms have bushings that are liquid filled and do rupture over time. Mine are ruptured right now, but I really don't notice too much. I think it was a logical thing for them to replace and that might have been gone. Just might not be the problem you brought it in for :)

You can check the sway linkages, the rods that connect the sway bar to the struts. I had that similar symptom, and replaced that linkage was my fix. Part are not too expensive, and very easy DIY.

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I'm surprised my first instinct would be to change those sway bar links.. but you can simply turn your tire to the side and push them.. if they wiggle without much force then they are worn. I think I got mine for $20 each for a MOOG set? I just like MOOG since I've always "upgraded" in the past and used them. Here's another tip.. you can do it, or should do it when the car is on the ground, if it's jacked up in the air and the wheels is sagging it'll make your life more difficult.

check the bolts the secure the upper strut tower brace to each tower and the firewall.. there are a total of four bolts. there is an old SIB out there for it. the bolts back out and cause the strut tower brace to flex and pop under load. replacement bolts are about $12 for all of them, replacement takes about 30 minutes. there is an updated torque spec for the bolts too. the ones that typically back out are the two at the firewall.

Thanks everyone! I'll have the mechanic check that stuff! :-)