Off-Topic: Your Mercedes-Benz hisses? Here’s the solution

Version en Español/Spanish Version:

If you have bought your brand new Mercedes-Benz (mine is a GLA) and, after a few weeks, it starts to make an annoying hissing sound when cruising the highway, you probably have a problem (the solution is below).

First, this is the sound that mine used to make:

It’s better if you use a pair of earphones, although it’s clearly audible without them too.

Be sure yours is making exactly the same kind of sound before telling your mechanical workshop about the solution.

It doesn't happen every single time you use your car, but when it does, it starts after half an hour or so, and it’s randomly hissing all the way to your destination. You don’t even need to go very fast: mine used to hiss even at low speeds of about 70Km/h (44Mph). It can drive you crazy!

The worst part is that you go to your official Mercedes-Benz mechanical workshop and they will probably say: “Well, that’s pretty strange. We've verified the sound, but there’s no much we can do about it. It seems an aerodynamics-related issue. You can pick up your car anytime you want”.

Well, great. Thank you for you useless help :-(

What I did was stick to my guns and tell them that I was not picking up my car until they found a fix for that. In my opinion there were only two options:

  • The problem was with the model: then they should fix it for everyone, including me.
  • The problem was with my vehicle: then they should fix it or give me a brand new one.

The car was brand new and I wasn't keeping it if it was malfunctioning. I think it is a no-brainer.

Finally, on my determination, they called Stuttgart and there you have it: an immediate solution directly from the central premises of the brand.

The problem was not related to aerodynamics. The problem was in the front-wheels brake pads.

They are badly design and sometimes can very lightly touch the brake disk while driving, even if you don’t push the pedal at all. That’s the cause of the annoying hissing.

What they did in Stuttgart was to slightly erode the pads in a certain way on the far edges so that the hissing stops. I saw the modified pads, but I couldn't take a picture. The eroding was done more or less around this areas (this is not a real Mercedes brake pad, but you get the idea):

The fact is that they knew very well what was happening since they didn't need to even inspect my car. They simply new the exact modification they needed to do, so my guess is that this is quite a common problem and they simple try to scam you a little bit by telling you to go. It’s a shame that a luxury car brand treats its customers this way. But you know: money is money…

It took me 3 weeks to have it fixed, but finally it’s working as expected :-)

What their post-sales representative told me after the fact, was that in the future probably all the pads for my model will have the modification if there are more cars with the same problem (as I’ve seen on the Internet, there they are). Anyway, since that modification is now tied to my car’s frame number, they’ll have them modified again in the future if I need a replacement.

So, the solution is: stick to your guns and don’t pick up your car. Force them to talk to the central premises. Even tell them about this article if you find it useful. But don’t settle on the fact that you need to live with the hissing if they told you so.

Hope this helps!