Mystery "drain hole" under windshield cowl

[MarinerZ4C]

The immediately previous owner of my ’06 Z4C neglected a few things which I'm working to remedy. The windshield cowl was very sun-damaged and brittle. When I removed it for replacement, I cleaned the “scuttle” area under the cowl thoroughly and reassembled it with the new cowl molding. It now looks as it should - BUT I have a nagging question. There's a circular opening (about 25 to 30mm diameter) which drains the center portion of the Scuttle area (under the cowl) - it's in a low spot to the left of the car's centerline. This drains the area in which the windshield wiper motor and mechanism are located – it’s not the AC drain. Should that round port have a rubber drain grommet or some sort of screen ? This seems to be the 'back door' that a mouse used under the PO's watch to set up housekeeping !

The hole I am trying to find out about is in the bottom of the metal scuttle (under the cowl) about where the yellow arrow points in photo of my engine bay. I placed a silver paint cap approximately under this hole. The silver plastic cap is only partly under it, because the positive battery cable won't allow it to move enough to the right side of the photo (left side of the car).

My good friend has a 2006 Z4 roadster, and when we checked, I was surprised that this hole is open on his car as well.

While I would like to think that my garage will remain mouse-free, I would like to know whether there should be screen or grommet valve in that opening.

Thanks for any input

[Clearancediver]

There is a grommet/rubber type "valve"…. I have it on my '04 as well. It was plugged with debris when I removed/cleaned it. I personally think it's superfluous but that's my opinion. It's designed to allow water to drain… same as the grommet/drain plug that drain the convertible top wells…

I don't have a mouse issue…

[MarinerZ4C]

Hi Clearancediver,

Thanks for the response. I found a thread pointing me to the part number (64116915666). I don't have a mouse problem currently either - but I live in a rural setting, and even driving over to a friend's house and parking for the evening carries a slight risk of critters looking for a nice home . . . I'll evaluate when I get the part whether to install or not.

[grannyknot]

Originally Posted by MarinerZ4C

The hole I am trying to find out about is in the bottom of the metal scuttle (under the cowl) about where the yellow arrow points in photo of my engine bay. I placed a silver paint cap approximately under this hole. The silver plastic cap is only partly under it, because the positive battery cable won't allow it to move enough to the right side of the photo (left side of the car).

I was just replacing my cowl other day and also noticed that second hole under the wiper motor, I can't find anything on RealOEM that would suggest there is a missing hose and if you look at the way the cowl is designed, little or no water should get near the wiper motor so I think that hole is a just in case.

On the other side, I think that rubber flap is more of a finisher than anything,
no self respecting mouse is going to let that stop him.
That drain tube on my car had a wad of leaves and pine needles in it that I flushed it out with the hose nozzle. Place the nozzle at either end of the drainage grid on the cowl and blast the water down, the center of that grid has a baffle to keep water out of the main air intake for the HVAC.