Gentlemen,

Gonna give it my best shot at explaining this one. For probably the last two years, I've been hearing a very rhythmic sound coming from what appears to be the right front wheel area when driving. I can only hear it when driving in a tunnel or next to something that will reflect the sound back into the cabin. And of course, the windows must be down or roof open. This sounds very much like a brake pad wear indicator in older cars. It only happens once the braking system warms up. As I understand it, our cars have a plastic wear indicator that will throw a light in our MFD when triggered, and not the older type metal indicator embedded in the pad. I pulled both wheels on that side and pads look fine. However, when spinning the front rotor by hand, it's doesn't spin freely. Takes a little bit of effort to spin it and there seems to be a small high spot that gets tight in the calipers but I can get it through the binders and it loosens up a bit. Wondering if that could be my issue, but I can't imagine that making a sound.

Happens with both my aftermarket and OEM wheels, so that's no it. I also checked the fender well area and see no visible signs of any rubbing whatsoever. Sound does not go away when brake is applied nor does it go away if I coast in neutral. There is that dust shield that sits behind the rotors, but when spinning the rotor, it doesn't seem to be rubbing against that either. Unfortunately, with only 1 jack and no jack stands, I wasn't able to effectively troubleshoot the rear wheel area. As our differential requires that both wheels be airborne to spin freely.

When I first heard the sound, I assumed it was time to change brakes. I put rotors and pads on all 4 corners (OEM) and obviously, that did not resolve my issue. I'm normally pretty good at troubleshooting, but this one has me stumped.

I'm calling on my MB brethren to help me solve this mystery.

Any ideas?

 

Is it there with 20 or 30mi? Does it get louder as speed increases?

 

What do you mean by "Is it there with 20 or 30mi? Do you mean 20-30 MPH? I start hearing it around 15-20 mph, and can hear it all the way up to the point that wind noise drowns it out. I can't hear it at all with windows up.

I wouldn't say it gets louder, but the tempo of the noise increases exponentially with speed.

 

Close the windows, roof and do not drive in a tunnel, case solved.

Could it be a bearing? Does the noise increase in speed as your speed increases? If so, then there has to be something rubbing. Since you say that it happens with both your sets of wheels, that would rule out a bump in a tire, if you are familiar with that, does it sound like it? (that would be more of a subdued thum thum thum BUT not a thump thump thump)

 

You sound like my wife. Her solution to any car issue she's ever had is to turn up the radio. As an engineer, that just makes me cringe. I must, MUST know the reason why things do what they do. I'm a complete freak show when it comes to that stuff.

Could definitely be a bearing. No chance it's tire noise. This sound has a metal on metal sound. Do you remember what old school brake pad wear indicators sounded like when you were getting close brake pad change time? Sounds very much like that.

 

Correction, I meant 20-30MPH. Check the if there is any difference in temperature between the wheel hubs after a 15-20min. drive. Raise up the rear, one side at a time, shift the car into neutral and check the free play of the of the rotor. What kind of an engineer are you?

 

Yeah, thought about that, maybe a sticky caliper. I would need one of those infra-red heat guns. Snap-On sells them, but I think they're hella expensive. Luckily, I have a friend that might have one...need to check. Sound definitely doesn't manifest until temperature rises in that area. Meaning, once the braking system warms up. Most likely, some metal is expanding and causing this, or it could very well be a bearing like stated above. But, I would think a bad bearing would make noise regardless of temperature.

I'm a Network Architect.

 

I had the same problem. Took them a while to find it.

No noise at low speed.
no noise when first started up and rolling down the block.
Noticed on the fwy in traffic and after a mile or so of driving.
Could hear it next to a curb on the side w/ window down.
Sounded like brake pad rhythmically dragging with wheel speed.
high speed could hear with window down, next to guard rail on fwy.
can't hear with windows up at any speed.
wind noise drowns it out above 70mph.
very noticable at 35mph with a car on the side of me and window down.
would go away when I hit the brakes.
not as noticable until the car was warmed up.
changed wheels/tires , same sound.

Brakes, right?

Nope!

other symptom...

The sound would not go away if I just dragged the brakes a bit, but if I hit them a bit harder, it would mitigate....

Turned out to be the left front wheel bearing.
It was scored up pretty good. I drove like that for 15k miles.

Glad it's solved!

 

A bearing should make noise regardless of temperature. I've had a few of those gone bad on previous cars. Nonetheless, it is possible that it is just beginning to fail. Jack up the car, front and then back, spin the tire forward and back listen for any abnormal sounds then see if the is any slight movement while holding and applying pressure, to the tire, on the front to back, down to up. I hope that helps. If there is no movement you should definitely be able to hear it. I can't see what else can it be, given the sound that it is making.

 

BINGO!

Exact same symptoms. So, the people saying bearing appear to be correct. Time for my next D.I.Y.

Thanks gents!

 

I had the same symptoms on the driverside front and it was the wheel bearing. Check your tires to see if they are cupping. When removing the wheel bearing, the first thing there is a nut, not a clamp as i originally thought becuase of the smaller torx bolt holding it together. Once you get that torx bolt loose, loosen the nut with a wrench. Sorry i dont remeber the sizes. Part is about $300+ from MB.

 

Bah, you misled me with the noise, it was more like a screech screech screech screech..... I've never done bearings, how difficult is it?

 

The hardest part is getting to the bearing. Remove connections to the batteries, remove the break caliper, knock out the rotor (with a 2x4 and a small sledge hammer) after you remove the holding torx screw and you are already there. You have to remove the 2" cap that give you access to the bearing with a screw driver and hammer. There you will find that torx bolt that hold the bearing nut (looked like a gold clamp to me) in place. Loosen that bolt and then unscrew the bearing nut with a large wrench/pliers and the bearing should come right out - at least it did for me. The bearing comes with the inner in the assembly and the outer one too. If you buy from MB, it comes loaded with green grease. Sorry, i should have taken pictures for a DIY when doing this.

 

Is this my part?


FRONT

http://www.rmeuropean.com/Part-Numbe..._5C1313F8.aspx

REAR

http://www.rmeuropean.com/Part-Numbe..._FE18869D.aspx

 

Same thing, genuine MB, but cheaper:

Front:
http://www.parts.com/oemcatalog/inde...layCatalogid=0

Rear:
http://www.parts.com/oemcatalog/inde...layCatalogid=0

 

DAMN!

Good find, thanks. Don't know why I didn't look there first. I just googled the part# and came up with that other joint.

 

stupid question but...is this covered by warranty? I swear that's the noise i am getting but they keep saying to replace tire (WTF)

thanks

 

Yes.

 

I got the same talk from some dealerships. The sound and the cupping of the tire starts when the bearing just starts to goes bad, but like with other MB suspension parts, it takes a while before you can pin point exactly what the problem is. I spent a year swapping tires that went bad after 2-5K miles. Then went to Prestige in NJ and told me my front left wheel bearing was loose. By the time i got to changing the bearing, it felt like my tire was going to fall off. No problems since then on my driver side.

I dont know if this might be the exact problem everyone is facing, but i've also heard that the bearing nut may just need to be tightend or it just was the tires - as Vette's problem was. Vette said Michelens were the only thing that made his problem go away after he swapped out tires. Although i respect Vette's opinion very much, i couldnt believe that my issue was tires - becuase off all the sets i went through (4 sets) and it was specifically happening to the left front only.

 

my own is more passenger front. 2 different dealers so far with the same "change tire" response. The same 2 dealers whom didnt want to change my oil and tranny fluid (one didnt even how to classify the tranny flush) at 39K because service E was not until whatever miles.
Its like, you have to diagnose and tell them what to do before they believe you or attempt to do it.

 

Definitely not my tires. The same noise is present with 4 different sets of wheels, with 4 completely different sets of tires.

I just ordered the front bearing. Will update.

 

There are good mechanics from MB dealerships, the problem is the better ones ended up starting up thier own shop. I believe the biggest problem with MB dealer shops is the Service advisors. They come between the relationship of the mechanic and customer - and most of the time they only read to you what is on the service sheet the mechanic wrote and cant explain what happened. When i had my honda accord, the honda service advisor would actually take me to the service area and show me what was wrong with my car. Even had a talk with the mechanic!

 

Simply request to speak with the shop foreman.

 

At the first dealership the foreman said i should change the tires, even after i told him i put 4 different tires and all ended up with the same result .

 

Did you use michelins? I found that the michelins run quiet with no issues. I went through 2 sets of "good as Michelin" other brands to find out they weren't