Soft Top Drainage Question

[3002 tii]

Only had my convertible for few months now and it's generally parked indoors. Unfortunately I had to leave the car with my local speed shop and it sat out for 1 day, the 1 day we happened to get torrential downpour. I figured one day of inclement weather couldn't do that much of a number but I was shocked to have checked the trunk and find that the rear right corner was damp. Pulled off the trim and the foam covering the right shock tower was soaked like a sponge.

Thing I don't get is even if the drain holes were clogged, why would the foam/shock tower area get wet? Is the water not being routed correctly downwards?

[Our03z4]

Originally Posted by 3002 tii

Only had my convertible for few months now and it's generally always parked indoors. Unfortunately I had to leave the car with my local speed shop and it sat out for 1 day, the 1 day we happened to get torrential downpour. I figured one day of inclement weather couldn't do that much of a number but I was shocked to have checked the trunk and find that the rear right corner was soaked. Pulled off the trim and the foam covering the right shock tower was soaked like a sponge.

Thing I don't get is even if the drain holes were clogged, why would the foam/shock tower area get wet? Is the water not being routed correctly downwards?

Is it wet behind the seat too? Not sure if water can go in the trunk, but it will go in the cabin. It's a horrible design, only has a small reserve before it overflows.

[3002 tii]

Originally Posted by Our03z4

Is it wet behind the seat too? Not sure if water can go in the trunk, but it will go in the cabin. It's a horrible design, only has a small reserve before it overflows.

Edit
Nothing behind the seats, and tried unclogging the rear right drain from the bottom but nothing really came out. Guess I'll have to try unclogging from the top.

[Huz-Z]

Back before I built my garage, my car was parked outside during summer (stored in winter) so it saw lots of sometimes heavy summer rain in the those first few years - but I never had this issue.

As I understand it, the two drain channels on both sides of the car, just behind each door, are supposed to channel away all water from the roof and allow it to drain to the ground. If one or both channels are blocked, water can build up along the roof / body seam that runs around the back window area and if its not tight there, then that combined with a partially blocked drain channel may be the source of the leak into the trunk.

But yeah, sucky design. I hope they addressed it and the top motor placement issue on the new Z4.

[gpraceman]

The right side drain is visible from top side, so it should be easy to confirm if that is plugged or not. The left side, where the motor sits, you cannot visually inspect, unfortunately.

[elerner61]

Drain cleaning (checking and suck/blowing from the bottom) is a regular to-do for roadies. I tend to blow first so as to not clog the drain with any material that might just be laying on the top. I'll jack up the rear a bit to get a better angle to get my hand in there (don't have terribly large hands so they fit without taking off that panel in the wheel well).

[dc_wright]

Here's a DIY on cleaning the drains. When they fill up the overflow runs over the back of the drain funnel, along side each side of the top compartment, and into the trunk just to the outside of the knobs that lower and raise the storage compartment tray. It'll soak the carper there and the foam underneath the carpet.