A customer came in with a wet rear seat. The immediate suspect was the sunroof. It’s not easily possible for a sunroof to be 100% watertight when it has to be able to tilt and slide, so there are drains that run from the four corners down into the wheel wells. After I couldn’t get it to leak myself, I lowered the rear part of the headliner enough to check that the rear drain tubes were connected and not clogged, and they were fine, so that meant looking deeper into things.
Removing a full headliner is never fun. I had already removed the entire rear seat to try to find the exact leak spot before, so this just added to the pile. I had to remove all the trim panels that touch the headliner, as well as the sun visors and assist handles.
Things were made a little trickier when I found out that you can’t remove the headliner from the car without bending it or removing the windshield, so I had to just lower it in the car and let it sit there and work around it.
We’d stuck a bore scope down the water channels in the sunroof and it looked like where they collect into the drains hadn’t been sealed properly, but when we took the sunroof completely out we found that wasn’t the case. At Honda’s direction we put the sunroof back in the car to check how much water was leaking through the seals. It turned out it’s supposed to leak only the smallest drops, but it was letting in a lot. The channels would hold the water just fine until going around a turn, and then they would overflow and get the rear seat wet.
We tried adjusting the glass, but it wouldn’t make it seal any better, so a new glass and seal was ordered, and it fixed the problem perfectly. If we’d known that before, I wouldn’t have had to take the headliner out, but sometimes this is how things have to go.