300E Front-end Knock/Rattle Sounds on Small Bumps

Try the anti-roll bar bushes - quite a common failing on these cars; they failed on my 260E and made some horrible clonks!

Al Bolton, G4VSQ

1990 500SE 1988 260E FOR SALE

==================

If the front end is anything like a 126 there are is a compliance joint on each side and they wear out. Do you hear a clunk on braking at real low speed?

side-to-side

Suggest you inspect the stabilizer bar's ends and its rubber bushings, also check the shock absorber bushings.

On my 126 you could hear the ball joints squeak and groan when you got in or out of the car. The compliance joints or track rod mounts are rubber joints that keep the front wheels from moving back when you brake or verse visa. When they are worn you get clunking on braking and acceleration. In my 83

300SD with 98k mi the noise of both the ball joints and compliance joints went away when it rained and water got in. And water is what caused the ball joints to go bad after the rubber boot cracked. I was quoted between $900 and $1300 for parts and labor by the independent Benz shops. Seems like they all use the same computer program for time beause times were within 20%, but different labor rates, parts were within 10%. I was lucky as I recalled seeing an invoice in a car that I tried out but didn't buy and they used Tulsa Wheel and Brake. I called them and they did mine for their estimate a little over $400, including alignment and that was July, 04 and it didn't take anywhere near as long as the others quoted. Three long trips and 12,000 miles later I have no complaints.

Thanks for the feedback! This group makes owning (and maintaining) the Benz a lot more fun.

The car does not make the sound during braking or acceleration. The rubber at the tops of the struts has a small crack around it at the top. I can't imagine that that fine crack is causing the sound.

From the feedback so far, I'm thinking that I need to replace some bushings. From Rusty's website:

There are two bushing kits I'm considering:

Front Sway Bar

L1049-36181 Sway Bar Bushing Kit Febi IN STOCK $15.45

Front lower control arm to frame:

L2040-34581 Control Arm Bushing Kit Lemforder IN STOCK $55.23

Here's the plan:

I will lift up the front end of the car and check the following:

1) Wiggle and inspect the sway bar to see if its loose in its bushings.

2) Put a second jack under the control arm and put some upward pressure on it to see if there is any play where it connects with the frame.

3) Wiggle the wheels side-to-side, left-&-right, and vertically up-and-down (in case I missed something the first time).

4) No one's mentioned motor mounts yet... but I will also check to see if they are loose or broken.

5) Other ? ? ? ? ?

(I have a bunch of new parts sitting on the shelf in my garage that I purchased online and didn't need... so I'm going to diagnose this one real well before buying this time... :)

Bob Murrysville, PA

Sorry, these are called "sway bar bushes" in US English. Very cheap and easy to replace, well worth doing anyway, even if they aren't knocking now they will...

Regards, Al Bolton ======================

Get somebody that knows these cars and drive and stop it at very low speed and have them look up there while it's moving. Whatever is rattling around in there will be very obvious to them then.

Might be, easy to check. Could be track rod mounts or the track rods themseleves.

The track rod mounts are reasonably cheap and easy to replace. The track rods themselevs are nasty compicated expesive (very) things, but they can be rebuild; there's a couple of ball joints in there. Unless the housing is cracked you should never need to get new track rods. Most of the used ones are buggered beyond repair, mostly from rust.

Well, I know my ball joints are bad so to speak (torn boot and a little play), but my mechanic said come back in 5000 miles, so I did and he said give em another 5000 (and he's not getting money on these check ups so it's not that). It's only $275/side so I'm thinking I'm just going to have him do it when I go home for spring break (I do a good amount of my own work though...anything special needed for ball joints like a spring compressor or something?) cause I don't like the thought of one corner of my car collapsing on the highway. Richard

replying to Bob, 300DBenzer wrote: smart man.