Help! '98 LS 400 Leaking tube from sun roof leaks behind pillar
 

I finally found the source of my leak. It is coming from an area behind the rear passenger side pillar. I poured water down the passenger side channel of the moon roof and see water dripping down the door molding just above where you see the top of the blue towel. It drips out into the bowl i put in the trunk (pictured), but slowly. Originally, I put a wet vac on the end of the tube in the trunk and got nothing. Although I do see a bit of what appears to be a green stain of sorts on the clear tube where it drains out of the car. I also, found a green algae like stain on the driveway. This side of the car sits in the sun in the evening and I'm in South Florida, where it rains alot. Humid too. https://cimg5.ibsrv.net/gimg/www.clu...80d5aa2411.jpg

https://cimg5.ibsrv.net/gimg/www.clu...44a5c8ddd1.jpgJust above the top of the blue towel

To me this makes me think that the hose somewhere behind the pillar has either developed a leak, or has come disconnected. Not knowing how it was engineered, I'm at a loss. Since there's water dripping from around the bottom of the pillar I'm thinking it's behind that pillar. Any thoughts?

To deal with the hoses you will need to remove the headliner. If those generations are like the older ones there is a plastic tray of sorts that is the moon roof drain system, it has a drain hose at all 4 corners. It is not going to be a fun job. Before you do that though the first thing to do would be to blow low pressure air up the hose it maybe plugged and allowing the water to run over the plastic tray. Also you could try stiff plastic like weed eater line but make sure the end it rounded so it won't cut the tube.
If clearing the tube doesn't work then the head liner is next. I suppose a clearing treatment is just temporary until the debris plugs it again. If your around tress line fir the needles can get in and plug the drains. Take pictures and do a write up for everyone else.

OK. I wasn't aware of a plastic tray. I thought the tube I see in the trunk, ran all the way from the rear/aft drain hole on the sun roof? Although I don't see the hole like I do on the the two forward. There are two drains forward that are like holes drilled in the metal and then painted at the factory. They're not stopped up at all. It's downstream from there where when I pour water down the sun roof aft drain channel, it leaks into the car where shown on the pic and then a little out the prescribed tube that is connected to a vent. Moreso into the car just at the bottom of the rear passenger side pillar.

This should help. That tube you have in the bowl should be connected to that brown tube on the right side of the bowl. That's where the water drains out of the car.

Good pics. Helps me understand what's behind the upholstery. Looking at your pics leads me to believe one of the connections to the tube has come undone. Now, to remove the upholstery to get at it. Any tips on removing the one pillar and it's associated pieces so as to get at the tube?

You have to remove the front pillar and rear pillar garnish on that side to expose the drain tube. 2 bolts for the front grip assist as well as the one in the rear. Lift up the hook for hangers that's on the personal light to reveal a screw. Once those are out you can use a plastic trim/pry tool to snap the garnish out.

low pressure air from a compressor (like 5-15psi) should be enough to blow the tubes clear.

Without removing any and succeeded quickly
 

I used a bore camera to find out the drain hole and inserted a copper pipe there as are shown below. I poured water to it and used a compressor to clean the hose. It's quite successful. It's also easier and quicker than to remove the pillar garnish.

Great pics and info, guys. My experience with this is identical to your issue. Park the car facing downhill. Blow low pressure air into the drain line near your Rt rear floorpan, followed up with a few ounces of water pushed up the line until you see it flowing through the front gutter, into the forward drain lines. Remove any debris that becomes visible. Continue flushing until clear. Unless the rear drain line has become disconnected, this will work perfectly. Pushing weed eater line through also works, but it often gets jammed up when it encounters a coupling or connector.

One thing to do is clean and recondition the moonroof rubber seal with Shin Etsu grease....

Leave moonroof open after treatment so rubber seal.can recover from compression set....then apply another coat of Shin Etsu grease...

Water must pass the seal.before reaching the drains..

Also, check all drain tubes..the one you suspect only because water is traveling down it when others may be at fault..

If you are unable to run a weed wacker type line up through drain tube, then a collapsed tube may be the issue.

Run fish line from from chassis up to moonroof drain ...found a micro-sized acorn in one of mine and pushing it down instead of up.might have caused it to jam in tube.