Hi All,

I have a strange sound problem after having the windscreen on my X356 replaced recently.
What made it difficult to diagnose was:
1) I made them leave the "cowl" off at the bottom of the window because I wanted to do some work on the wiper motors (actually the water spray pipes), and install it myself later
2) Just a few days earlier I installed new tyres and didn't have much road time in between.

When driving back after the new window installation, I have a strange low frequency sound, that sounds like wind noise, coming from the window bottom area. The frequency does not change with speed, and it starts quite slow (45km/h).
At the time I thought it was because the cowl was off. And yes, it definitely became much softer once I re-installed the cowl. But it is still there.

What is also weird is that it goes quiet when I drive onto smoother tarmac and back again when going on to "normal" tarred road. As if it originates from tyre noise. (But I did not expect extra road noise from the Michelins I put on)
With the cowl off I imagined that I could hear noises like the supercharger more clearly.

In the last week or so I realised that when I stick my head forward, close to the windscreen (while driving) then it very clearly comes from the window. With my head in that forward position my ears are in some kind of "perfect spot" to hear an amplified version of the sound, almost a boomy version of the "wind noise"

Then I noticed that at the bottom, where the window meets the bottom/inside of the cabin, there where you can hardly see or reach, is what looks like self adhesive foam tape. It is stuck onto the body (not the glass). I never noticed it before, but also never looked down there before. Now I wonder if that was always there?
Can anyone check & confirm please?

Then I did a test and stuffed an old cloth into the length of that valley. Noise gone! (or much dampened)
Now I have lots of thoughts going through my mind - is that bottom part of the window actually open to the outside? Did they forget to put "glue" on the bottom part of the frame? Did they mess something up and stuck a piece of foam tape on the car to make up for it?
This weekend I will do some tests with a hairdryer on the outside while someone listens on the inside. I can't think that the (respectable) window shop would cover up a problem like that, but who knows, anything is possible.

Any suggestions or idea? I don't really want to go back to them, how will I convince them something is not right? Do I really want them to work more on the car?

Thanks!