LALALAND

Hi All,

In the last 2 months I have start to encounter noisy brake from 45+ mph in fast deceleration to a traffic light. It's sound like hummmmmmmmmmmmmm before coming to a complete stop. At low speed, 25 or 35 mph deceleration, I don't heard the noises. Seem to me the sounds are from the front. I don't feel any brake pedal vibration nor wheel vibrations.Took the car to 3 car washes in last 2 months after the weather clear up in SoCal as I thought it might be brake dusts l. Car is currently at 35k miles
1) is the car telling me that I need new brake pad?
2) warped rotor(s)?
3) rust on rotor(s)?
4) or it's normal and or I'm just being **** and picky about the sound.

Let me know what you think. Will schedule a visit to the dealer within next week.
Thanks in advance!

TeeEl

Did your car sit in or after the rain? That can cause the aforementioned rust build up on the rotors that just needs to be burned off from braking. Two months should be plenty of time though, especially if it's a daily. Generally if the rotors are warped you'll feel it in the pedal and sometimes the steering wheel. 35k seems low for pads to be going bad unless you're really hard on them.

Arrie

Check your pads. Low mileage but if all city driving pads can go quickly.

KEY08

Can’t be overnight rotor rust. That comes off after only a few stops. Could be worn pad.

Arrie

I have rotors covered with rust all the time and it never has been a problem.

Pad wear is the first to check and knowing the wear sensor is only on one side on each axle the pads on the side without sensor can wear off without knowing it. This would mean there is something wrong if one side wears a lot faster but this can happen.

KEY08

Yes, my experience with MB is that the inside pads wear much quicker than the outside pads. Unless you take off the wheel, the inside pads cannot be checked for wear.

Mud

If the caliper slides or piston are sticking the inside pad can get toasted. This is what happened on my car on the non-sensor side.
https://mbworld.org/forums/e-class-w...2011-e350.html

SteveE400

I'm betting that you need new rotors. My E400 did that, literally overnight while stuck in storage at the dealer awaiting diagnosis of a different noise. One day, all was well. The next. . . hummmmm to stop. The rotors were glazed so bad that no amount of hard stops at freeway speeds could clean them off. The car had 28,000 miles on the clock.

I had the rotors and pads replaced, and at 32,000 miles now, all remains quiet.

I have no clue why or how this happens, and it shouldn't.

thedanofsteel

New member here, new owner as well recently bought a used 2012 E350. I had the same issues (still do) about this noise. I'm sorry you have this too but also glad that it's not just me. I brought it to the MB dealer I purchased from and they advised me the rotors were pitted. That this can come from certain acidic wheel cleaners that some car washes use. Replacing the rotors is the only answer, according to them.

Marcorati

Amazing the BS dealers will tell you to get to replace parts. They are telling you a Mercedes can’t even hold up to a car wash before the rotors disintegrate. Don’t other cars go through car washes too. Mercedes w212 in notorious for warping front rotors. A bi-product of being such a heavy car.

Arrie

Use ceramic pads and rotors stay clean. No need for new rotors with surface build-up. Cleaning them is fine and good ceramic pads do this just fine.

LALALAND

Okay just got the car back after been there for 4 days. Can't find anything wrong with brake. Checked bearing and it's fine. Service adviser suggest that it's the tires. Front brake pads still has 8mm, rear pads 6.5mm. LF tire 5 mm, rf 5 mm

Here were other items I went to the dealer for:
Check for driver side front suspension for noise over speed bump. Even though I shown the SA when he was along for the ride for brake noise and suspension, the mechanic said can't duplicate. SA suggest if it get worse, come back. I will see if I can get a good recording of the noise to show them in the future.
No water from AC drain on ground after 20 minutes. They checked and verify the drain hose are connected. Didn't tell me if it was clog or not.
A5 service
There seem to be a open campaign 2018110006 - 1802P54A16. Used Xentry and update the ECU. No idea what this is for. Anyone know what it is? Maybe it's nothing important (emission cheating?) =D
They found transmission mount to be weak, and replace it under warranty. Hopefully this will reduce the occasional rough down shift from 5 to 4.

nc211

I don’t know about the open campaign but would love to know more!

When I bought mine at 22k miles (CPO), I changed the rotors and pads around 25k miles as part of my process of making the car “mine”. Used genuine MB parts, nothing aftermarket. Had a little shimmy and a groaning noise too. Groaning noise turned out to be bent rims, which is more pronounced when you brake as your shifting more weight down onto the wheels.

The new rotors and pads were perfectly fine until I had the 40k service done at the dealership where they flushed the fluid. I don’t know what they did, but it’s never felt the same since then (November 2018). I’m likely to replace them again myself but not with OE parts this time. I’m getting skipping in my brakes, a sign of worn pads. I suspect the inside pads are dragging and suspect the fluid change somehow wasn’t done correctly.

I also suspect i still still have a bent wheel. But I’ve only driven the car about 3,000 since November so haven’t really been focused on it.

Here is what I’ve come to realize with my initial experience with Mercedes Benz (this car is my first). They’re great cars, nothing quite like them. But their dealership network absolutely sucks for service in my area (DC). I have heard from many owners around here and now seen for myself - they’d rather you just buy another one instead of properly fixing the one you’ve got. The only way to really get them properly serviced is to either learn how to do it yourself, or find that good indi mechanic who knows them. Here where I live, I found him at silver star motors.

Check your rims. If you have the 18” amg rims, it would not surprise anyone here that you might have one (but usually two) with just enough of a bend to trick you into thinking it’s the brakes. Smooth until more weight is applied to them (braking). Good thing, it doesn’t cost an arm and a leg to fix one ($150 +/-). Wouldn’t waste the money on a dealership to fix it for you, they’ll just call the guy you can call yourself and double his fee to you..

SteveE400

If your noise is a creaking sound that happens when you compress the left front spring, like when you slowly go over a speed bump or when you go through a dip in the pavement, it may be the same one I had. My car would "creak" whenever I went over speed bumps, etc. I took it to the dealer and showed them how to make the noise. Over the course of some seven weeks at two different service departments, they replaced the left front strut, strut bearings, anti-sway bar links and several other small parts. Ultimately, they admitted that they just couldn't find the cause, and like you, I was told "If it gets worse, bring it back again."

I agonized over that noise for 3 1/2 years! I was almost ready to go car shopping. THEN I decided to do my own research. I looked back in all the MB forums (fora?) to when the W212 chassis was first released, searching on topics like "front suspension noise." I quickly found a post from around 2010 in which the OP had the same noise! He somehow realized that this might not be a mechanical noise and searched the unibody shell. He found that when you drive a W212 sedan over these speed bumps, the body flexes more than we think it does. When the body flexes, the hood moves back and forth on top of its plastic and rubber bumper stops. He lubricated the 4 (or was it 6?) plastic bumper pegs that the hood rests on when closed, using silicone grease. VOILA! Noise gone. I tried the same, along with rubbing a bit of the grease on the door, hood and trunk weather strips. WOW! My car has never been this quiet.

Now, if I can stop the symphony of noises happening behind my instrument panel, I can really enjoy the car. . .

TeeEl

Someone else (or maybe you?) mentioned that on another thread. I'm hoping the OP isn't hitting undulations at over 45 mph though. I'm having similar squeaking to what you described, so I actually picked up some silicone paste a few months back. I haven't gotten around to applying it yet though. Damn I'm lazy.

LALALAND

The suspension noise can be heard after going up then down the speed bump, then the noise. Stupid office building management put these big 3 inch tall, 8 inch width, and 12-15 feet across all over the parking garage to slow people down a year ago.
As for silicon grease for hood rubber bump, I have a unopen bottle of 303 aerospace protectant . Do that work as substitute? If not any recommendation for grease available from autozone or oreilly's?
As for rim, maybe it's was bent from all those pot holes due to the raining season earlier this year. Not sure if my rim is bent. Wonder if costco tires will check it out for me as I need to get the tires rotated front to back. I'll ask costco if i can pay to have them balance again.

SteveE400

Any of the auto parts stores should carry silicone grease. WD-40 makes a gel lubricant that should work, too - just don't use the liquid spray and expect it to last. I am not familiar with 303, so can't comment, but if it is a non-petroleum lubricant, it should work.

nc211

I wanted to come back to this with a minor update to my post above.

had my car inspected for its annual state safety sticker. Car was up on the lift and I could see the pads - they’re fine and don’t look like what I thought might’ve been the case (inside pad drag). So not sure what the cause is for me either on the brake noise groaning at speeds above 45. I’m guessing just crappy design flaw that can be fixed like others have stated with aftermarket parts instead.