There is a technical document from Mercedes relating to noises from the front axle caused by upper and or lower arm bushes.
Please see the details below to see if this fits in with your complaint
click on this link for a document containing photos: Suspension arm Photos
Best regards, Paul
Grunting/creaking noises from the area of the front axle when braking or negotiating tight corners
The cause of the noise complaint may originate in various rubber mounts in the upper or lower control arm.
Rear rubber mount of lower control arm (1): In order to restrict the movement of the rubber mount when braking, an oval plastic stop plate is integrated in the rear rubber mount of the lower control arm on model series 164. When braking or cornering, this stop plate comes into contact with the rubber-lined outer sleeve and can cause grunting/creaking noises.
Front rubber mount of lower control arm (2): The rubber mount comes into contact with the body when braking and can cause grunting/creaking noises in model series 164 and 251.
Front rubber mount of upper control arm (3): The rubber mount comes into contact with the body when braking and can cause grunting/creaking noises in model series 164 and 251.
As optimized rubber mounts are not available at the present time, replacing the rubber mount or the complete transverse control arm is not a long-term solution to this problem!
We therefore recommend treating the aforementioned rubber mounts on problem vehicles with wax.
The attached pictures show the points to be waxed on the individual mounts.
Apply the wax to the entire circumference of the mount.
To do this, it is best to use the spray lance supplied in order to apply the wax accurately.
In the event of complaints, treat all the aforementioned mounts to prevent future problems.
The rear mount of the lower control arm on model series 164 can only be treated when the vehicle is standing on its wheels. This is the only way to apply the wax accurately on the parts causing the problem.
Please observe the drying time of the wax: approx. 2 hours!
Please report any vehicles that suffer repeat problems after waxing of the mount, quoting the mileage since the repair, to your local MPC.