Soon after I bought my 2004 MCS in December 2014, I made sure water drained through the sunroof channels and out the holes at the front. Read much on the forum about that not to check it. Water poured out the bottom of the car as it should. There was evidence of water stains (dry at the time) around the right side A post but figured that was from an issue in the past. Then a couple of weeks I noticed water on the rubber floor mats and of course the carpet was wet. Dried it out with a heat lamp and knew I had a problem somewhere, most likely the drain tube.

We had a long stretch of cold rain today with my car parked outside. Tonight I see the carpet is wet with water drops alongside the ends of the dash near the door jam. Removed the A post trim and could see that water had channeled down the inside to the dash end. Then I worked my way up and into the headliner. Found the corner of the headliner was wet about 6 inches around the A post. I expected to see the drain tube off one end but it was fully on both tubes and looked to be dry. Water could be felt on the headliner near the metal drain tube but I couldn't figure out where it was coming from. I pulled the rubber tube off and couldn't find any cracks or leaks. Even gave it a minor pressure test and all was okay. Getting late so I zip tied both ends of the rubber tube and put it back together leaving the A post trim off.

The rubber sunroof seal next to the roof edge looks okay with no gaps that would explain water getting in that way but I’m not ruling that out either. It may be possible for water to get between that seal and the roof metal. From there it could go over the mounting flange for the sunroof and drip down near the drain tube. Just not sure if that is possible. EDIT: Found this post about the sunroof seal so I may be on to something.

Think I’ll slip a piece plastic or aluminum foil between the headliner and the roof in the area of the leak. Then I’ll give it a good soak with the hose sometime this week and watch for leaks. Back to drying out the carpet with the lamp. If anyone has ideas I’d like to hear it.

 

Just a wild guess but could the rear drain tubes be leaking or weeping and the water running along the sunroof to the front of the car. If you open the tailgate, you will see the drain holes for the rear drain tubes. When you open the tailgate you will see what looks like a large rubber grommet in the top corners. These are the rear drain holes.