Hello,

I have a 1993 W124 Coupe (300CE) and have a problem that my mechanic can't seem to figure out...

There is a low speed rolling noise that happens anywhere from around 3mph to 10mph.

- Can't tell what side it's coming from (e.g. front / back / left / right)
- Can hear it pretty well in the interior of the car
- Can hear it when the brakes are applied
- Can't hear it if gas applied
- Changes frequency with speed

It sounds like a "whompwhompwhomp" type sound.

My mechanic tried to repack the wheel bearings but the noise persists!

Thanks!!

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1993 300CE

You can usually determine what side of the vehicle a noise is coming from if you find and drive alongside a wall with the windows down, usually a mall or supermarket has enough wall to do this on its side or rear of the building.

As far as the sound itself, it can't be heard while spinning each wheel separately on a lift I assume? From the description it appears that it would likely be a tire with something in it such as a nail or something, or the rear axle's CV joints often make a sort of muffled sound such as you're describing.

Bearing sound is usually described as a growl, so that doesn't seem like what you're hearing.

My first impression is that it's a tire. I had a volvo that made an odd rhythmic noise that could only be heard at times, particularly low speeds. Couldn't isolate where it came from. Sometimes I'd feel it when braking or sometimes with my foot on the gas. Most times I could only hear it. Could never figure it out. Then one day, going around a turn at low speed, POW, blowout on the right rear tire.
As soon as it happened I realized that's what the noise was. I was lucky, because generally FLEW around in that car.

I will try figuring out what side it's coming from by driving alongside a wall.

I don't think it's the tires since I just switched to my winter set and the noise persisted...

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1993 300CE

How about a wheel (rim) barely rubbing against a slightly bent [brake] backing plate? Could just be a slightly warped rotor rubbing the brake pads (or a worn ridge on a rotor).

Another thought, I just did the brakes on my W124. I changed out the rear rotors and I was surprised to see the poor condition of the parking brakes. They were very rusted and with large pieces of brake lining having fallen off and rubbing against the spinning rotor. Mine didn't make any noise that I noticed, but I could easily see where such a situation could make some low growling, grating sounds.

A stretch I know, but just some things coming to mind that might not otherwise be considered! Obviously there's a laundry list of rotating, moving parts along the entire drive train that could produce hard-to-pin-point noises.