Hi, I have a 2003 C230K Coupe and within the last few months it has developed a rumbling noise with a vibration that I can feel through the floor. It only occurs at low speeds and is smooth from 40mph onward. I have changed both front wheel bearings, anti roll bar bushes and drop links (also had knocking at low speed full lock turns which seems to have stopped now ) Front brake discs and pads are less than 3 months old. Could it be the thrust arm bushes (also referred to as control arms or camber caster arms ) They seem to be perfect, no tears or cracks. Has anyone else had this symptom and found the problem as it's really beginning to annoy me. My other half is getting sick of me turning the radio up and down asking her to tell me where the noise is coming from :-) Is it possible that it could be tyres ? I cannot try the rear ones on the front as they are a different size. Any help or ideas would be fantastic.
Regards, Gavin.

 

I used to have a BMW 3 series before I got my C230K. I had basically the same symptom. And unbelievable rumbling (more like a "roaring" noise) coming from somewhere but I couldn't discern where no matter what I did. It was most prevalent at low speeds, and I could really hear it in a parking lot just cruising at 10mph or so. I never would have believed it was a tire problem, but it was. I had put a set of Kumho Ecsta tires on the car in place of the Michelins. When I went to the tire dealership here and told them about the noise, they said these tires, when worn down to about half the tread life, were famous for doing this. A new set of tires and the problem was completely gone! Now, having said that, I'm not saying this is your particular noise.
Always check all the bushings first. The sway bar bushings wouldn't make a roar at speed. A bad tire internally can. Other bushings might, so check everything in that department to rule it out completely. Brakes....well.....I've heard some odd brake noises but it was usually an out of round rotor and it only did it when you hit the brakes hard. So I don't know there. You can always go to an independent shop who will go for a test ride with you for no charge to get another opinion. Don't pay for this though. They should do this gladly. Hope this helps you in some way.

 

you have a W203 which had bad problems with caster thrust arm bushings breaking they are the silver arm which connectoto the lower control arm and goes out in a angle to the ubframe the bushing which breaks is the one at the subframe it will either leak all fluid /oil out or be cracked all the way through you will be able to see this with a flash light . also check the front strut link to sway bar (the front tire will have to be removed ) they tend to break internally causing a knocking sound as well these parts are releativly cheep

 

The thrust arm bushings went on my C230K at about 70K miles, but they leaked out a nasty looking black lube on my driveway when they were shot. But as worn out as they were, they never "roared" at low speed. Really tightened up the steering when they were replaced.