This just started happening. I am guessing I need to seal something on the outside. Only happens when it rains.....

 

Sunroof / moonroof drains probably clogged. There are 4 drains - one in each corner of the sunroof tray.

It's easy to see how those things are working on this video:

I had like one car (Nissan) in the shop where tubes / hoses for the drain shrunk over time and pulled off the nipples on the sunroof. Otherwise cleaning / unclogging them fixes the problem.

Google / youtube around how to clean them. There are long small brushes available on amazon for this purpose. Search for something like "sunroof drain cleaning tool".

 

Peter, thanks for this information!

 

Got a snake wire with brush off Amazon $10. Will clean it out and hope that takes care of the problem.

 

If it's not the sunroof drains, it's very possible it's the seam sealer on the roof. It happened on my car on both sides and it took me forever to figure it out. I should have made a thread detailing it back then.

Pull the A-pillar trim off inside the car. Spray with a hose from the bottom of the door, then the windshield, bottom to top on both. See where it starts leaking from. You need 2 people. Mine was a pinhole crack in the factory seam sealer.

I've never found a post about it on here, but I saw 1 other guy mention it on a FB group, so I'm sure it's happened to more than just 2 people.

The fix can be a pain, only because taking off the trim that runs from the back of the roof to the bottom of the windshield is a complete pain in the ass. AHC garage on YouTube does it in a video and he describes the technique quite well. Be very gentle and expect some clips to break. You'll see a tiny hole if that ends up being your issue. I used some automotive silicone and made sure I got it in the hole and the area around it.

Hopefully it's just a clogged sunroof drain. But if not, this very likely could be the issue. Definitely start with the sunroof drains though. Also could be the seal around the windshield. Report back when you find the issue.

 

First step, I put Draino down the hole. An hour later, I flushed with water and it all came out near tire. Nothing in the inside airbag area.

Later today, the brush/snake arrives and I will use that and test with water.

 

I also had a seam sealer hole on my 08 odyssey. Similar leak location (but on right side).

At the time this was very common on Honda/Acura suvs/vans. Never heard of it on a car (eg: TL) though.

 

wow ballsy of you to put a caustic chemical like that anywhere near your car….