Whoever thought it was a good idea to put a non-weathertight hole in the roof of a car?

Hoping to call upon some clearer heads on this one. 

I've got an 03 Vibe with a big dumb hole in the roof. For moon seeing I guess. Anyways, it's nice in the summer, but for the other 9 months of the year, the damn interior of this thing feels like a terrarium. I can feel the moisture on the passenger front seat, but it's not wet so to speak, just damp. The passenger front floor's jute under the carpet is wet, wet enough for me to just remove it. No pooling of water in the that area, just wet. The moisture doesn't go past the floor "joist" where the front seat bolts land, and no other parts of the floor are wet. 

I've since pulled the headliner out so I can more closely inspect the moonroof assembly. 

Key points: 

1. All four moonroof drains are clear and running free (and hooked up). 
2. AC has not been run, and it does not run when the defog runs. I know this isn't ideal for condensation, but this water situation isn't from condensation
3. Door seals look good
4. Floor plugs are good
5. Windshield seals look good and I don't see any other visible seal damage anywhere now that the headliner is out

My thought: 

I park at home on a slight incline (nose down), and during particularly heavy rainfall, the front two drains are getting overrun with water and simply can't keep up. The water then backs up into somewhere else on the frame that isn't water tight, draining down into the cabin. 

My test plan: 

1. Dry out the car
2. Sit in the car and have a patient helper spray the car down with the hose
3. Hope there is a visible leak somewhere
4. Seal the damn moonroof up if I get nowhere with it

Any input from the hive? I consider myself a fairly capable wrench, and it's absolutely driving me nuts that I can't seem to find the leak in this rig. 

Is the drain hose clear in the rear?

On the Vibe,  the drain goes all the way to the passenger side rear. In the trunk area, pull the plastic trim on the passenger side. There is a blue hose that terminates after the rear wheel.  That hose is known to kink and therefore not drain.

https://forums.genvibe.com/phpBB3/viewtopic.php?t=20505

I think too that I have read that in the first year, 2003, the hose was too long in the rear. This causes the hose to sag. When the hose sags,  it kinks like a garden hose causing no water to flow.  The answer is to tape a splint onto the hose like you would a broken leg. A small section of wooden dowl  can be taped to the outside of the hose.

Even just tape can make the hose more rigid.  Picture from the  rear interior wheel well of a green Vibe

Blue tube routing...

This is my own picture of the blue hose from my build thread.  This was a 2003 too.  Notice what seems to be too much hose after the nozzle of the heat gun.  This car too was sunroof leaking.  I cleaned the drains at the roof and pulled the hose more through the body of the car so as to take that last curve out of the hose making the exit a more direct slope (not yet done in this picture.)  I sold the car immediately (which was always the plan) so I have no history to weather this solved the issue.  

Since the blue hose terminates on the outside of the car, also check for obstruction at the outside portion of the hose.  Being that the hose is located after the tire, the hose will be subject to road grime, etc.  

Parking on a nose down slope might be hurting your water flow given that all the water needs to flow to the rear of the car. Its my understanding that at the sunroof there are 4 drains (2 forward and 2 rear) but no matter of where the water begins to drain it all still terminates at the blue hose in the passenger rear wheel well (rear of the car.) 

Try parking with rear down.

I don't have a Vibe but just wanted to say what a great response by John to the OP. That's got to help.

In reply to Feedyurhed :

Thanks for the props. I lived the frustration. It's counterintuitive that a problem in the center of the car (water down a-pillar and water on passenger seat) has a solution at the rear-most of the car. 

I look forward to a pic from the OP when he opens up that rear trunk trim. I expect a crimped/collapsed hose. 

Another thought.  If you zoom in on this picture you will see that there is a door/cover intended for reaching tail light bulbs.  

If you have taken to storing something in this area, like jumper cables or a first aid kit, it is possible that the item is resting on the blue hose and causing obstruction.  

I have had at least three vehicles with factory sunroof and they all leak. I see my rover is leaking again, 12 months after I replaced one drain and cleaned the other. And I never open the damn things.

bearmtnmartin (Forum Supporter) said:

I have had at least three vehicles with factory sunroof and they all leak. I see my rover is leaking again, 12 months after I replaced one drain and cleaned the other. And I never open the damn things.

I berkeleying Hate sunroofs for this very reason.

I've caulked them shut on at least two different vehicles as a nuclear option to solve the leaks.

It's still sort of wild to me that sunroofs really are just a hole in the roof with a gutter system INSIDE the car. I know it's normal, but it still seems like a bad idea.. 

It's also kind of funny that power sunroofs seem to break their own glass as a failure mode a lot more often than the other power windows break their own glass.   

It's also nice that to get to the sunroof guts you usually have to pull headliners and the headliner is the closest thing to a one-time-use trim panel there is in the car since a bunch of cars literally can't get the headliner out without flexing the crap out of it and some of the trim clips/attachments on some headliners are almost impossible to remove without damaging the headliner.

The first sunroof i ever owned dumped cold swamp water down my back the first time i slammed on the brakes in that car.  I've actually had very little problems since with all my personal vehicles that had sunroofs, but i consider it luck, not that sunroofs aren't time bombs.

Just an awesome deal all around.

John Welsh said:

Another thought.  If you zoom in on this picture you will see that there is a door/cover intended for reaching tail light bulbs.  

If you have taken to storing something in this area, like jumper cables or a first aid kit, it is possible that the item is resting on the blue hose and causing obstruction.  

John, thanks for your comprehensive reply! 

I have checked the rear drains before, and sure enough one side was kinked and flatten by the factory interior plastic of all things. 

But, your reply has me going to check it again sometime today. 

But to clarify something, there are four unique drains, one in each corner of the car the corresponds to that corner of the moon roof. I hate to say that I am intimately acquainted with these stupid things. 

Stay tuned for an update! 

Vigo (Forum Supporter) said:

It's still sort of wild to me that sunroofs really are just a hole in the roof with a gutter system INSIDE the car. I know it's normal, but it still seems like a bad idea..

It's always surprised me that they work as well as they do in most cars.  I've got a glass moonroof in the Jeep, solid metal sunroof in the BMW.  BMW so far is dry as a bone.  The Jeep has only leaked once in the 11 years I've owned it.  There was some ice built up around the sunroof seal on a barely above 0 degree day.  But it was bright and sunny, and the Jeep is dark colored.  So the ice melted in the sun, seeped through the seal and filled up the gutters.  The lower drain tubes were still frozen in the cold, so the gutters couldn't drain.  Went to drive the thing and the first time I hit the brakes, a few ounces of water poured off the front of the headliner onto the dashboard.  Never encountered the right conditions to re-create that problem again. 

I have had five cars with sunroofs.  BMW, two saabs, and the Landrover (with two sunroofs) I use them anytime it is not raining or snowing, and never had an issue with leaks.

I've had one leak.  I've had to rebuild one before also, not fun!

They are also noisy as berk if you have a roof rack.  I almost never open one and I do try and avoid cars that have them.  

Good luck OP!

Never buy a retired squad car.

I owned one car that had a factory fitted sun roof. It was a Jensen Interceptor and the cost back in 1976 was an extra $1000 for that option - when that was real money. 

The drain tubes were buried inside various panels and access required dismantling half the car. When one became blocked I learned from one poor Jag owner who had decided he could clear the drains by sticking a compressed air hose in the top of the drains with the sun roof retracted (monumentally bad idea!). All that did was blow the plastic hoses off the steel nipples up near the roof, resulting in a major disassembly job.

I made sure that the tubes were clear near the top using a length of stiff wire and then got under the car and located the ends of the drain tube (not without some difficulty) and blew up it.  A big 'splut' of goop and all was good.

Spent some time this afternoon folding myself around the interior of the Vibe with the hose going on the roof. 

A while back I had a Volvo moon roof where the seal had shrunk and then began leaking as water would catch in the area between the seal and glass, landing...somewhere. 

Anyways, my hubris of believing that it had to be the tubes had me overlooking this very visible seal shrinkage failure. 

Watching this from inside the car, there is water absolutely pouring into the tray from this point, and I'm wondering if it's just far enough back to be sloshing out of the channel. It also seems to be traveling elsewhere once it gets behind the glass as there is another spot further on the passenger side (ding ding ding) where it's leaking down as well. 

Is this the issue? I sure hope so. Because every drain tube is clear and kink free, and I can physically watch then draining completely free with a huge amount of water (hose). 

A few minutes with some flowable silicone later:

It ain't pretty, but then again neither are wet floors. 

Once it cures, I'll give it another hose down and see what's what.