macolam1123

Greetings,

I've got a facelifted 2012 C200, was doing fine as a daily driver until 2 weeks ago. I was going home after an hour of driving, braked downhill for junction with 1/2 pedal travel at around 30-35mph. When the car decelerated to around 20mph, the front brakes started to hum all the way till it stopped.

Same hum noticed again a week later under similar situations, only on a level surface this time.

I took it to the dealer for a check, they got the pads replaced and resurfaced the rotors but it still hummed during one of their test drives, although under what situations it hummed was not described by the mechanic.

A week passed and they still can't find the fault and blamed my aftermarket rims (19' genuine rays, without spacers) instead as they claimed that the hum was gone during their test drive with stock rims.

However, during the 2 weeks from the first hum to getting the car checked, it only hummed twice with the car still being daily driven that this hum should be quite rare. If the rims were causing it, it should have hummed every time I braked under similar conditions since it first started humming, if not since I installed the wheels 18+months ago but that's not the case that the wheels should not be causing this.

I wonder if anyone could shed some light on this or have experienced similar hum, any input would be appreciated.

ps. Its front brakes were also checked some months ago by the dealer for some other noise and they also blamed the rims for that, I wonder if the rims could really caused it all...

Thanks in advance

capt_paul

The rotors are not supposed to be resurfaced, so I am surprised the dealership did not remove and replace the rotors.

I would perhaps try another dealer or have some higher level of MB intervention

macolam1123

This is not the first time that they resurfaced my rotors that I thought this would be a acceptable practice, at least this was told by the man in charge of my case

Sadly, looking for another dealer over here in Hong Kong/ having higher level of MB intervention is not quite possible as Mercs here were handles by an sole importer/distributor that factory services could only be done by them or warranty would be voided if the car was serviced by other workshops

MDMercedesGuy

Mine has a hum braking at highway speeds under moderate load - and they will howl if you get onto them really hard on the highway. It's definitely heat related - if the brakes are cool it is quiet. I had a loaner C250 with 17" wheels that did the same thing. I went on a ride with the shop foreman from my dealer, and of course that morning it was cooler out and they wouldn't scream.

It's something I have learned to live with. It's not covered under warranty, and it is just a noise (no vibration or such). With any luck, I'll be moving to an ML in a few months so that will take care of the issue.

macolam1123

Tbh, the first time I heard that hum after canyon run so the brakes should be properly hot that your saying sounds valid to me.