Help with water leak and identify part

[ruffles]

Hi everyone. I'm new to the forum and I'm looking for some help with the 2007 Z4 3.0SI that my son just bought. We are getting water in the drivers side footwell. I've been searching all over the net and it seems like door seals are a common problem but I believe I've eliminated that. We removed the seat and pulled back the carpet and with him inside, I sprayed water on the drivers side window and there was no leak. When I sprayed water on the windshield, we get a small stream of water entering from behind the pedal area.

Here is what we've done so far.
1. Tested the cowl drains and confirmed they are not plugged up. On the passenger side, I can see the exit near the bottom of the engine. On the driver side, I can't seem to find the actual exit but I did confirm the water comes out the bottom of the car and does not back up into the cowl.
2. I replaced the windshield cowling with a factory new piece. The old one seemed like it was in good condition but we thought we would give this a shot based on what I read in other messages. Someone else mentioned water getting in around the windshield wiper motor. Our car doesn't have anything covering the motor (besides the cowling). When I installed the cowling, I put a small bead of silicone between the cowling and the glass to make sure it would seal up and any water running off the windshield should be directed to the cowling drains.
3. I replaced the rubber seal/gasket that goes around the top and sides of the windshield (also used a very small bead of silicon)

After that, it still leaks . Looking at it more, I see there is a tube going into the firewall that is loose and not well sealed. I've identified it the pictures. What is this piece and do you think this is the problem? Any other suggestions you have for us?

Thanks in advance for your help!!

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[bigwinn]

Does the water feel ‘sticky’ like it’s got antifreeze/glycol in it?

If yes I’d suggest the coolant pipes that run to the heater matrix have split or failed

Worth a look under the dash?

[Zedebee]

There is a drain under the cowl on the drivers side, same as on the passenger side, have you checked that?
The piece that goes from the airbox to the firewall is the sound generator. It should be fairly well sealed but it’s very unlikely any water will get in here, and definitely not in the drivers side.

[Mr Tidy]

Hi to you and your son, and welcome to the forum.

I just noticed you are in the USA, so the Sound Generator will be on the driver's side! It's only there to pipe a bit of induction noise into the cabin but if it isn't fully seated I suppose it's possible some water may get in there.

Good luck solving the problem.

[enuff_zed]

I'm not certain how the LH drive cars are laid out, but in the UK the Yaw Sensor is under the drivers seat, beneath the carpet.
If this gets wet it causes all manner of odd issues with traction control and abs. It is also very expensive, even as a used part.
I would recommend that you look for this and ensure it is dry, whichever side of the car it sits.
It mounts under a black bracket which has to be unbolted to lift it up.
A good recommendation, even if it is dry, is to seal it inside a poly bag, with a packet of silica gel for company.

[ruffles]

Thanks for the tips so far. The water didn't seem like it had any coolant mixed it and we haven't noticed any odd smells. I'll dig deeper tonight to try and find the cowl drain on the drivers side. LOL at a sound generator. I think that could be it because it looks like it is just loosely hanging there. Fingers crossed!

[Zedebee]

If my comments/orientation didn’t make sense, it’s because I didn’t clock it was a LHD car

In which case the sound generator could be the problem, but it’s still hard to see how the water would get in there.

Another possible ingress point could be the cabin filter, but on your car I think it’s passenger side.

[ruffles]

I stopped by the BMW dealership and one of the service people said the sound generator should have a tight sealed fit and another said it shouldn't. What say you all?

[enuff_zed]

I stopped by the BMW dealership and one of the service people said the sound generator should have a tight sealed fit and another said it shouldn't. What say you all?

Yes it should. It's a tight push fit into the grommet on the bulkhead. I retro fitted one on wifey's 2.5i and it took a couple of attempts before I got it pushed tight in.

[DMike]

I stopped by the BMW dealership and one of the service people said the sound generator should have a tight sealed fit and another said it shouldn't. What say you all?

Yes it should. It's a tight push fit into the grommet on the bulkhead. I retro fitted one on wifey's 2.5i and it took a couple of attempts before I got it pushed tight in.

Second that. But the location doesn’t really get exposed to water and unlikely to let in any significant amount of water. Looks dusty on the images as well.

[ruffles]

Sorry, I forgot to report back on this. Sealing up the sound pipe appears to have solved the problem. Previously, with the hose on the windshield and the driver's side carpet pulled up (US car), we would see a small trickle of water coming from behind the pedals. Now, with the sound pipe sealed with some silicone and properly fitted, no water. We also verified that after holding the hose on it for a while and then opening the hood for inspection, there was definitely water on and around the sound pipe so we are feeling pretty good about this fix.