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How to: Fix/Unplug Cadillac CTS-V Sunroof Drain Tubes.

What you will need.
1) Flat head screwdriver
2) Philips head screw driver
3) Weed Whacker wire
4) Drywall knife (optional)
5) Approx. 2-2 ½ hours of your time

I know it’s a big problem with sunroofs, and instead of paying a dealership a boat load of money, I decided to figure it out myself.

If you open up your sunroof, you’ll see in each corner small holes for the water to drain out, down the tubes and out of the vehicle. To access the tubes, you’ll need to drop the headliner which is a lot easier than it looks.

How to take out the side A pillars:
1) Each side pillar has one (1) Philips head screw behind each airbag clip. Make sure to take that screw out before removing the A pillars, front and back. If you don’t, you will end up ripping the plastic piece off and have to buy a whole new A pillar. (Like I did)
2) Also, the side pillars will need to be taken out as will, but are not held in with a screw. They are held in with metal and plastic clips that easily come out with a nice tug.

How to drop the headliner:
1) First thing you will need to do is take out the three (3) Philips head screws out of the driver’s side and passenger’s side sun visor. After doing that, you’ll also need to take out the clip that holds the other side of the sun visor. The driver’s side is held in with a one (1) Philips head screw, and the passenger’s side is held in with a ten (10) millimeter bolt. (NOTE, there is a ground wire connected to this bolt that will detach from the bolt. DO NOT LOSE IT.)
2) After you have done this, pop the front dome light out, and just let it hang for now.
3) Once that has been done, move to the rear seats where you will have to take out the “Oh shoot handles.” Both sides are held in with two (2) Philips head screws.
4) After doing that, you’ll have to pop rear dome light out and unbolt the ten (10) millimeter bolt. There is no ground wire attached with this one.
5) Once you have removed these items from the ceiling of the car, carefully start to pull the head liner down, making sure it does not buckle. (NOTE: when you pull the head liner off, the dome lights and sun visors will be connected by wires. You may disconnect the wires, but I found you had plenty of room to work without disconnecting them.) You will have to disconnect the defrost wires, front and back.

Finding the drain tubes and cleaning them.
1) If you look up at your sunroof after you have taken the headliner out, you’ll notice the tubes and each corner of the sunroof. INSPECT THEM THOROUGHLY!
2) Each tube is held in with a rubber hose connect. It is your choice to replace these. They become brittle and begin to wear after years of weather abuse. Location in the pictures
3) Disconnect the front tubes from the rubber hose connect, (sometimes pulling off the nipple of the sunroof drain) and pull it down just far enough to give a good blow into it. If you hear air coming out near the door hinges, means it isn’t stopped up or clogged. But now is a good time to run your weed whacker line through the tube, and give it a few more good blows. Pictures below.
4) Visually inspect the nipple at the sunroof to make sure that it is not clogged.
5) After doing the front, leaving them disconnected for now, move to the back and repeat steps 1, and 2. But in step two, the water runs down the tubes, into the trunk of the vehicle, and exits at the bottom of the rear fender well. Same for each rear side. Location in the pictures.
6) Locate the drainage spot by removing the trunk inner liner, which is only held in by a few plastic twist on caps.
7) After removing the inner liner, you’ll see the drain tubes coming into the trunk and into a rubber seal. Remove that seal from the fender, and remove the tube from the seal. Inspect the seal and the tube for any clogs, if they are clogged, clean them out with the weed whacker line and by blowing from the upper part of the drain tube.
8) GM decided to put a “X” in the rubber seal where the hose goes in, I decided to cut that out with an sheet rock knife, giving the tubes better flow.
9) Reassemble all the hose connections, top and bottom. I personally used a sealant on the rubber hose connect to help with the leaking. After doing that, put the rubber seal back in the fender well, and put the inner interior back together in the trunk.

After you have unclogged the tubes, and put it back together, it’s time to put the headliner back into place. Repeat the steps above in the “how to the headliner” in a reverse order. Make sure to have a helping set of hands to put the headliner back in.

Now you’re set! I hope my “How to” helps everyone with their leaking sunroof. Feel free to contact me if you have any questions.

Thanks guys!
Dylan Wolfe.
 

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Discussion Starter #3
Re: How to: Fix/Unplug 04-08 Cadillac CTS-V Sunroof Drain Tubes.

I posted this in the wrong one.. Whoops.
 

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Positive update here:

Couple years ago I read some discussion here about clearing the moonroof drain tubes, specifically the one over the driver seat. Lazily, I decided to blow compressed air through it and low and behold, it got worse, I had blown the hose off of the fitting.

After the torrential rain (and tornadoes) on Monday and Tuesday this week, and the dripping I had to endure on my 30 mile commute, I'd had enough. This morning the weather cooperated well, not too hot and humid, and more importantly, a bit overcast.

I did a little googling about accessing the drain tube and got out my trusty tool box.

Removing the sun visor and clip, then on to the "airbag" symbol, I was able to disconnect the speaker connection and place the pillar aside. A little elbow strength and I had a perfect view and access to the disconnected drain tube and I easily reconnected it.

I elected to try the weedwacker wire trick but couldn't get it to pass. I looked in the doorjamb and under the car, even removed the inner fender for access. No luck. Tried using mechanics wire to force the supposed debris out. Again no luck.

Time for the compressor. I disconnected the tube again, and also from the pillar. I took the venturi type nozzle off of the fitting and the hose fit perfectly in it. Gave it a quick blow and heard it clearly blowing out of the car. For added assurance, I tried the weedwacker wire again with no luck.But I had some success.

I put it all back together again, poured some water in it and watched it pour out the door jamb. Opened the door to find the tube but couldn't access it.

Oh well, after about an hour tops, more from accessing my tools, I completed the task.

I hope this helps others with this problem.

Next up is replacing the air vent actuator. Still a GD good car at 112K.

Happy Motoring!
 

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Super Moderator 2005 CTS-V
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Thanks for bumping this one up. I had the rear seat removed and when I went to reinstall it, I found a puddle on the "shelf" where the seat cushion sits on the passenger side. Looked up and found the C-pillar and headliner were wet. I'm guessing the drain tube must have come loose from where it attaches to the sunroof assembly.

I haven't tackled that yet, but I did access the rear drain tubes where they pass through the trunk and dump into the rear wheel wells. Got some muck out of both of them back there. I also blew air down through the forward drain tubes and verified it was coming out in the door jamb. (I'll try to remember to post pics of where the forward drains come out.)
 

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Super Moderator 2005 CTS-V
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7,698 Posts
With my girlfriend's help, I finally got around to dropping the headliner to address the leaking sunroof drain. Still not sure we actually found an issue, so we left pretty much everything disassembled so I can see what happens the next couple of times it rains, then reassemble everything if there's no additional signs of moisture in the car.

We ended up not dropping the headliner fully. As stated above, I had blown air through the forward drains a while back, so I knew they were clear. Since we only had to get to the rear drains, we only dropped the rear of the headliner (after unnecessarily removing the A-pillar trim, the sun visors, and the front dome light - oh well :rolleyes: ). Used my little shop vac to both blow through and suck through the two rear drains. Got a bit of mung out of the driver side rear drain, so maybe that was the issue? I'm not sure that was the issue, though, because it was over on the passenger side where the headliner and C-pillar trim got wet. We'll see what happens once we get some rain.
 
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