: How To Clear The Sun Roof Drain Tubes

03-14-10, 04:28 PM
Courtesy of Lifer

Around the inner portion of the sunroof is a trough that collects and directs water that seeps in through the seal, just like the lower rear of a convertible top. Not high-tech, simple, yet ingenious in design. There are four rubber drain tubes running out of the trough, two in front and two in front. The rule is do not use compressed air to clean them as this will blow the tubes off the nipple connectors and you will have to remove the headline to access.

Interestingly, if you drop the rear panel in the trunk, the one held on by four nuts along the top edge, where the trunk light is, you can easily access the drains as they come down, and are plugged into the body's floor hole. Easy to get to there. Pop them up, squeeze the flapper valve and the dirt pours out.

So I opened the roof and on each side poured water from a glass and the rain in the inside from the headliner continued, proving the problem was probably the drains.

Wait - there's more. To clean the drain tubes it was suggested using .080 weed wacker string to rod them out. Two problems here. The first is that the rear drain holes are not visible unless to have x-ray vision. Hard to get to, even though they are in line with the trough. Second, the string is usually in a coil and not straight - hard to work with.

So, a trip to the Wally Mart and after looking for wire, rods, any stiff item, I found the perfect one. Solutions Peerless Dryer Vent Brush, 10 feet long, IPC 0 3916610417 8. The label is blue.

Perfect. I cut off the brush leaving a brass nut, a short spring that is very flexible, and another brass nut, then 9 feet of black, stiff, but flexible rod, and a handle. I filed the front nut smooth so it would not catch, and then easily fed the rod into the rear drains. Super. On the left side it went all the way to the flapper at the bottom. On the right side it hung up - the tube had gotten between the electronic panel and the trunk's back wall and was crushed flat. I freed it up, unflattened it, and the water poured out. I retested with pouring water in the trough on both sides and no water entered the inside of the car. Then I closed up the car and drowned the roof, windows, and all openings for 30 minutes with my water hose. No water inside.

Rangers comments:
Might consider cutting off the flapper at the end to prevent future clogs.

11-29-13, 02:26 PM
I was told by the guy who sold me my '01 Catera that the drain tubes were between the front and rear doors behind some sort of panel (he had to unclog them himself less than a week after purchasing the car). Does this differ based on model years? The problem needs to be corrected immediately as the water that is now trapped in the rear driver side door is freezing and I'd like to prevent the floorboards in my car from being damaged. I'm a female college student who fortunately knows a little bit about cars (but clearly not enough lol), so any help is appreciated! :)

01-23-14, 11:11 AM
I own a shop, I was working on a customer's Caddy and his sunroof drains were clogged. I removed the front wheels and wheel well/fender splash shields, partially, and found the rubber drain valves at the end of the drain tubes. They had a very fine sediment in them. I squeezed them and mud started to ooze out. Then drops of water I poked the mud with a straight metal pick tool and more water flowed. Finally I had good water flow and the tube emptied. I then blew the line out from above at the sunroof drain hole. Poured water in the trough and had good flow. Repeated procedure on other side.

At the rear, the the lines were clear all the way except for the check valves/rubber flappers which were full of sediment just like the fronts were. I removed the trunk interior liner enough to get my hands and a light in the area where the drains were, disconnected the white (LH) and black (RH) hard drain lines and cleared the flappers/valves. Poured water in sunroof trough and water flowed from all the wheel wells. Thanks Ranger for the above post because I didn't want to blow the lines off inside the car by blowing on them with compressed air. Your post was helpful and though this is 3 years after the fact, this is still a common problem and the thread lives on.

05-30-14, 07:53 AM
Any picture of dryer vent brush?

05-30-14, 08:36 AM


Ben Davis
06-14-14, 02:43 PM
I have a 2004 DeVille base model with a leaky Sun roof.
I located the front drains easily and shoved a .80 piece of weed-wacker string and it went down about 5 feet and would not continue. Tried bending the first 1/2" of the string and re-inserted it and it would still not go past that point. On to the trunk. Removed the upper panel and found the drain tubes feeding into a hard nylon 90 degree pipe then to another rubber tube and on outside. Removing the hose from the sun roof and see dirt and sand coming out. Tried pushing the wacker string through and it went about the same length as the front and would go no further? I see no flapper on either side of the rear system. SO it seems the front drains are still clogged. We are just getting into our rainy season here in Florida and I need to fix this, Any other suggestions?

06-14-14, 06:53 PM
Flappers are on the outside of the car if factory sunroof. Is the tube clear from elbows to outside? Some have had luck with using air pressure to clean them but can knock hose off the sunroof completely and cause more issues and must be done with caution.
If you pour water into sunroof is it making it as far as the elbows?

06-14-14, 08:32 PM
Yeah, you might try pouring water in and let it sit for a day or so to soften up the dirt that is clogging it.

09-23-14, 10:12 AM
For Karl L - Your non Tech Tip post has been moved to the proper "DTS" forum.

01-22-17, 12:30 PM
I have a 2008 CTS sedan with sunroof. I had this exact problem. This works great and the dryer brush is perfect for this.

I was able to access three of the four drain tubes without dropping the headliner. For the rear two, I can access one of them through the battery compartment. There is a connector there for the side of the tube that goes up to the sunroof and down to the wheel well. However, in the trunk I cannot locate the rear driver's side tube anywhere. There does not appear to be any tube where my trunk light would be. Can someone please post a picture or is it possible to insert the dryer brush at the drain location at the wheel well? I see where water drains at the wheel well, but I cannot locate the actual hole that it is coming from. Any help is much appreciated, thanks.