Racking my brain on what to do . . . .

When i go over a high frequency bump (driver side) the suspension makes a noise. It's not a clunk, it's not a squeak. It's like a wobble noise - metal on rubber. Wobbly in that it's not a one clunk, but a rattle that's not metallic. Does any of that make sense. Whatever is making the noise is going left right left right left and then stops. It's often when I roll over a manhole cover that's just an inch or so below grade. Or if they put a patch in a road.

It's not the sway bar bushings - everything seems tight. I can't get anything to to move with a pry bar.

I've read lots of w211 forums on these things. I took it to a local indie and they said it was the motor mounts. I did them myself and although the car needed them, that wasn't the culprit. Is there a technique to eliminate each bushing?

I'll drive the car and try and hit the bumps with one side or the other and it seems as if it's only prevalent on the driver's side. This is like 25 mpg on city streets.

any thoughts about where to start? I want to take it to the dealer and see if they can diagnose, but it feels like this is one of those things where you just start randomly replacing parts until something does it. Is there a way to check the strut mount?

thanks,
dave

 

Does the noise sound like it’s on the inside / interior?

 

no, it's definitely suspension - it sounds like bad sway bar bushings . . . . but it's not.

 

I chased a suspension noise, or so I thought, that ultimately led me to change every component. Even used the OEM supplied microphone system to try and locate the noise. Car was a 211.056 or RWD 2006 E350. Had a dealer tech help out as well.

Noise happened at speeds and bumps as you described.

no kidding - the noise ended up being a crumbling left most dash vent. A friend was in the car and said ... what’s the rattle in the dash ... to which I said that’s the suspension noise I’m chasing. He was sure it was an interior noise. I started looking in that area and found a broken piece of plastic. Took that vent out to look further and it was broken in several places and would rattle over bumps. Took it out and glued it back together - noise gone. I chalked up the work to preventative maintenance to ease the pain.

 

Could be one of the control arm bushings. Sometimes spraying bushings with a synthetic lubricant (not petroleum based, it can eat the rubber) can help quiet them down, obviously not a permanent fix but a good way to isolate the problem.

 

So I put the car up on jacks and had my kid turn the steering wheel left and right. I don’t think this is the noise, but. Sounds too metal on metal

 

I got underneath and it’s definitely making a clunk sound as my kid does the steering wheel left and right. How can I tell if it’s the coupler making the noise or the rack?

has anyone done this on the 4matic with the exhaust below the rack? Do I have to remove the exhaust?

trying to find the coupler part, but to no avail. I think the rack has to come out to replace.

 

Inner or outer tie rod ends? Or do these cars have a bushing in the steering rack where it mounts to the car?

 

Start the car while you do that just to confirm noise is still there. The compensator in the rack is pressurized only when the engine is running.