W124 brakes
 

Relatively new to Merc ownership (Nov. last year) so this may be a silly question, but here goes:

When I first start up and pull away, after just a few seconds/yards travelled, a distant "whirring" can be heard, and a vibration felt through the brake pedal. Just the once, then all is OK. Is this normal, some sort of adjustment the brakes have to make upon start up? Or do I have something else to worry about?

Thanks, guys

Stevey
1995 E220 estate (wagon)

Probably Normal
 

Welcome Steve,

The sound and feeling you describe is probably the ABS (antilock brake system) activating. I notice it in my '88 260e only if the rotors are wet (like when the car sits outside overnight), or a tire is low. My wife's '92 300e seems to do it one every time the car is started. Either way, I think it is normal but you may want to verify your tire pressure and make sure all your tires are the same size. The ABS system senses if the wheels are rotating a different speeds with bad tires may not operate correctly.

John

My brakes do exactly the same and it is a bit unnerving. However it doesn't just happen once: if I am moving at very slow speed and have to break (your usual traffic jam), I get a thud and feedback in the pedal (that happens very rarely). I was reading about the issues that my 300E initially came with and found that there was some problem with ABS (if braking at low speeds, the squeal would activate it, consumerguide.com).

Any ideas?
Thanks.

Check the pads and rotors for condition and pad brand -- aftermarket pads can be grabby and scream, and if they do funny things the ABS can activate. Causes a vibration in the pedal.

I only have activated the ABS two or three times -- once when trying to avoid the deer I hit and a couple times on ice, never on first starting off.

Next time you change pads, make sure you break them in correctly (that is, very gentle stops only for the first 100 miles) so that they don't groan just before the wheels stop turning, this may activate the ABS.

peter

Thanks, was just planning on changing those pads.

Clean your ABS sensor wires on each front wheel.
The one in the diff at the back is a little harder to get to.
Dirt and/or metal shavings in the sensor end that connects to the wheel sometimes causes the ABS to misfire when coming to a stop.