Many of our C4 100/S4s and A6/S6s (and B3s and B4s) were equipped with either steel or glass sunroofs which live in a sunroof "cassette" bolted to the roof of the vehicle. The sunroof seal is not perfect and some rain water and snow melt will seep past the seal, into the sunroof cassette. To manage that water and keep it from entering the car interior (and wetting and destroying the headliner), the sunroof cassette has four drains, two in the front that go down the "A" pillars to the front door hinge area and two in the rear that go down the "C" pillar and exit in the rear wheel well, behind the liner.
These drains need to be kept clear so that they drain. Otherwise water can leak into the interior. Access to clean the drains is achieved by opening the sunroof all the way. Methods that have been used successfully clear the sunroof drains include weed-wacker nylon "string" (pushed down the tubes) and old speedometer cables. High pressure compressed air might be too much for the tubes. Canned air (like the stuff used to blow out computer key boards, etc. has been used).
Here is a diagram of the location of the drain tubes and a photo of a sunroof cassette exposed after the headliner board was removed:
Base photo courtesy of IrishS2 (Eric) on the S2Forum
FRONT DRAINS (SEDAN AND AVANT)
Here is a photo of the front left C4 sunroof drain exit point:
Steve M says "The front drains exit in the front door jambs- they are difficult to get to, but rarely clog."
REAR DRAINS
SEDANS
Here is a photo of the left rear C4 sedan runroof drain exit point (right side will be similar):
Steve M says "Rear drain is just behind the rear wheel well, and are more likely to clog because of the rubber 'valve' similar to the one in the cowl area. You can get at them with the bumper installed, but they are a lot easier to see with it off."
AVANT REAR DRAINS
I couldn't find the rear drain on my S4 avant so I asked for photo help on the S2Forum and here. With the help of Marco from Montenegro(Majorcina on the S2Forum) and Doug W (islingtonaudi) and Mike A. from here, I got the photos that I needed.
The factory diagram is not specific to the avant and is vague as to what happens. What I discovered from the photos below is the rear avant drain goes down inside the avant's "D" (rear most pillar),into the two storage cubbies, just past the avant rear corner taillights and into a grommet that is just to the rear of the cabin air vent. I just confirmed this on the V8 S4 avant. (Watch the sharp edges on the metal if you sick your hands in the cubbie holes - they will slice you good (don't ask))
Left side (Majorcina was doing a repaint so he removed everything, even the sound deadening foam):
Photo Courtesy of Majorcina on the S2Forum
Right side:
Photo courtesy of Majorcina on the S2Forum
Here is the big view:
Base photo courtesy of Majorcina on the S2Forum
Here is islingtonaudi's right rear drain on his V8-converted 1997 A6 avant:
Photo courtesy of Islingtonaudi on quatttroworld
Here is Mike A's left rear drain:
Photo courtesy of Mike A. on quattroworld
Back to Majorcina, here he is with the left rear drain grommet pulled out of the body:
Photo courtesy of Majorcina on the S2Forum
None of these avant drain exits can be seen easily with the bumper on.
Now that you know where the drain entrance and exit points are, there is no excuse to not periodically clean out them out to prevent water in the cabin and headliner fabrics from coming loose. (But that is another post - to come).
These drains need to be kept clear so that they drain. Otherwise water can leak into the interior. Access to clean the drains is achieved by opening the sunroof all the way. Methods that have been used successfully clear the sunroof drains include weed-wacker nylon "string" (pushed down the tubes) and old speedometer cables. High pressure compressed air might be too much for the tubes. Canned air (like the stuff used to blow out computer key boards, etc. has been used).
Here is a diagram of the location of the drain tubes and a photo of a sunroof cassette exposed after the headliner board was removed:
Base photo courtesy of IrishS2 (Eric) on the S2Forum
FRONT DRAINS (SEDAN AND AVANT)
Here is a photo of the front left C4 sunroof drain exit point:
Steve M says "The front drains exit in the front door jambs- they are difficult to get to, but rarely clog."
REAR DRAINS
SEDANS
Here is a photo of the left rear C4 sedan runroof drain exit point (right side will be similar):
Steve M says "Rear drain is just behind the rear wheel well, and are more likely to clog because of the rubber 'valve' similar to the one in the cowl area. You can get at them with the bumper installed, but they are a lot easier to see with it off."
AVANT REAR DRAINS
I couldn't find the rear drain on my S4 avant so I asked for photo help on the S2Forum and here. With the help of Marco from Montenegro(Majorcina on the S2Forum) and Doug W (islingtonaudi) and Mike A. from here, I got the photos that I needed.
The factory diagram is not specific to the avant and is vague as to what happens. What I discovered from the photos below is the rear avant drain goes down inside the avant's "D" (rear most pillar),into the two storage cubbies, just past the avant rear corner taillights and into a grommet that is just to the rear of the cabin air vent. I just confirmed this on the V8 S4 avant. (Watch the sharp edges on the metal if you sick your hands in the cubbie holes - they will slice you good (don't ask))
Left side (Majorcina was doing a repaint so he removed everything, even the sound deadening foam):
Photo Courtesy of Majorcina on the S2Forum
Right side:
Photo courtesy of Majorcina on the S2Forum
Here is the big view:
Base photo courtesy of Majorcina on the S2Forum
Here is islingtonaudi's right rear drain on his V8-converted 1997 A6 avant:
Photo courtesy of Islingtonaudi on quatttroworld
Here is Mike A's left rear drain:
Photo courtesy of Mike A. on quattroworld
Back to Majorcina, here he is with the left rear drain grommet pulled out of the body:
Photo courtesy of Majorcina on the S2Forum
None of these avant drain exits can be seen easily with the bumper on.
Now that you know where the drain entrance and exit points are, there is no excuse to not periodically clean out them out to prevent water in the cabin and headliner fabrics from coming loose. (But that is another post - to come).
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