Originally Posted by 03Mach69Mach

The design of the plastic sunroof drain connection at the firewall is very poor and is the cause of 95% of the interior water issues in this car. People theorize many issues (i.e. windows, sunroof seals, windshields etc.) but those area of leaks are minimal if any. The sunroof drain comes down both the drivers side and passenger side windshield pillar behind the dash to a plastic grommet type fitting mounted to the steel fire wall. The grommet has a rubber gasket at the fire wall. With the heat from the engine compartment on the fire wall, interior temperature fluctuations and three different materials (plastic, rubber and steel) expansion/contraction, its understandable how this area is prone to leaking. Also, when it leaks, it runs down the firewall, behind the interior insulation under the carpet to the foot wells and collects. The reason you don't see the water underneath the carpet by pouring a bucket of water is because it has to saturate the pad and work its way downward. A heavy or extended rain allows enough water to makes its way there and collect. And once it's in that foot well area, it won't easily evaporate or dry because the back side of the carpet has a vapor barrier to prevent water from your feet on the carpet from soaking through. So once water is in the foot well area, it's going to accumulate until you either suck it out or it gets above the carpet. If it gets that high, you run the risk of damaging electrical components. Mine got so high one time that the door courtesy lights stayed on while driving and flickered based on the roadway pitch. The sunroof seal allows a lot of water to get around the glass, but the sunroof is designed with drains at all four corners to evacuate the water.

The only way to avoid these issues is to re-route the front sunroof drain water from the fire wall area to below the vehicle like the rear sunroof drains do. That eliminates the exposure to the interior much like the AC condenser eliminates the condensation through the passenger side floor. Because of the location of the firewall drain grommets, it makes it difficult to access them to modify them to put the water further into the engine compartment, although there is documentation that some have completed this with success. I re-routed mine after paying the dealership $900+ to repair the grommets which eventually failed some 11 months after they repaired them. The grommet part cost something like $2.00 but the remainder was to remove/reset the dash to gain access to these grommets. Search this forum for leaks and you will find prior posts about re-routing the drain lines. It costs very little and after two years, my car is bone dry with no leaks. It's not the sunroof seal, not the AC drain, not the windows, not the windshield seal and probably not even the electrical bulkhead behind the battery (if you haven't run a power line for an additional subwoofer amp to your trunk via that area). Its the plastic grommet type fire wall drains for the sunroof. Poor engineering and dealerships who don't care to fix the car outside of the manufactures parts and original design. Love my car and love the overall engineering, quality. But the sunroof drains are the dumbest, least thought out and poorly engineered car design.