:) Hi, my wife's BMW X-3 has a Moon roof that has leaked. First thing that you have to do is to find the bottom of the drains. They tend to stick shut as they dry out. Usually pinching the ends with your fingers will un-stick them. Open the roof all of the way and locate the drain holes. With a small funnel, I pour Simple Green down the drains to clean the dirt out of the tubes. Then I flush the drain tubes out with several gallons of water.
But even if you do a perfect clean out, in a really hard California down pour, the drains aren't quick enough. We now keep this car in the garage and out of the rain. This will be our last Sun Roof vehicle.