Picked up the LR4 from the shop after the oil change. They poured water into the driver and passenger side drains and said the driver's was flowing freely while the passenger's was flowing slowly (and leaving some water in the passenger's side footwell). I told them to go ahead and fix it by putting **** eater string through it, or whatever. They declined because it was Friday afternoon and they didn't know how long it would take once they got into it. They did mention they had blown some compressed air through it, but didn't want to be responsible for pushing a **** eater string through it because that could cause some additional damage to the drain tube. I asked what I was supposed to do until they could carve out some time to get it fixed correctly. They said to throw a tarp over it or something that would keep additional water from getting in. I told them I would be down to pick it up. Not happy.
I'd been watching YouTube videos on how to clear a sunroof drain and gotten several different takes. They ranged from scraping around the opening with a pipe cleaner, pulling off the vent screen and fabricating a new end to the drain tube, to pulling off the A pillar and headliner, and dismantling most of the lower dash and electrical components surrounding the glove box to isolate the source of the leak. Once home, I decided to start with removing the vent screen. It looked effortless in the LR3 video. After pulling on it a few times to the point that I felt it was about to break, I decided to look for additional videos on the topic, and hopefully something that was LR4 specific. I found one where the guy was looking to upgrade from the old screen style to a more updated modern version. He admitted up front that it wasn't going to be pretty pulling out the old vent screen, that it would require a lot of force and would probably destroy the old screen. He reefed on it and finally popped it out, admitting he was lucky to get it out in one piece. I decided to take a pass of the vent screen, for now.
Instead, I decided to attempt to unblock the tube with a wire. I'd seen one video where a guy did it with a cheap indoor extension cord. He had cut off the male and female connectors and split the two rubber coated wires down the middle, pulling them apart to make two single rubber coated wires of equal length. I tried feeding one of those through the drain tube, as it seemed less aggressive than resorting to the **** eater wire. That worked, kind of, until it got about 6 inches down the tube. Then it just bound up and could not be fed any further. I decided to take out the big guns and went to the **** eater line. I was able to feed that all the way down the drain tube and plunge it in and out a few times in the hopes of breaking up whatever was creating the blockage. After that, I poured a little water in the driver's side tube and it drained right away. I saw the same water dump out behind the front tire a few moments later. Looked like the same amount of fluid. I did the same with the passenger's side and it went in okay and came out a bit slower. I still guessed the volume was about the same, but it was hard to tell. I scrubbed the passenger's side tube another time and then decided to try some more water. Hot this time. That seemed to do the trick. the hot water flowed right down the tube like it was being sucked through a vacuum and rapidly spilled out behind the passenger side front tire. Success.
I still may want to go up under the headliner or behind the glove box or remove the vent screen to see what is going on behind the scenes. But, for now, prudence seems like the better part of valor. I just wanted it to be good enough to not flood the interior while it rained over the weekend. It seems like I may have accomplished that goal.