UrS4boy

Most of our C4 100/S4s and A6/S6s are equipped with either steel (92 MY) or glass (93 MY to 97 MY) sunroofs. The sunroof lives in a sunroof "cassette" attached to the roof of the C4. 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).

BB1995S6

I need your help I had a leak about 3 months ago and it ruined my headliner. Had a shop pull the headliner and check for leaks found none? Said the drain tubes were clear? Had a new headliner installed and when I got the car back the rear of the sunroof sits lower than I remembered? Just went out with a garden hose and rinsed the car on water is coming through the seal as fast as I pour it over the sunroof? Is this normal? There was a lot of water going into the rear tray and none in the front? Then when I went to open the sunroof to check the tray I could not get it to stop in the closed position? It would go from open to vent and then go up and down a few notches without me touching the switch. The switch was in the closed position . Finally I got it to shut by opening the sunroof all the way and then turning the switch to the closed position it finally stayed shut. But it would not shut from the vent position. Oh and last night the sunroof vented it's self when I was not in the car and it was in the garage? Help is the water in the tray normal? I think it needs to be adjusted or maybe calibrated? I'm not sure but I don't want to screw up my brand new alcantara headliner....


Thanks mike

UrS4boy

a) Sunroof seals don't keep all the water out, hence the rain tray and the four drains. You personally need to make sure that they are clear as per the post above.

b) Sunroofs like to do strange things when the battery voltage gets low. Check that.

c) Your sunroof might be out of sync/timing. With the sunroof closed flat, remove the sunroof control panel using the suggestions in this photo:



Then check the timing:

BB1995S6

What do you consider low voltage? 12.1 on my fluke just now. Should water be running into the drain tray? All I was doing was letting the water run over the glass portion and it was running not dripping into the tray when I opened the sunroof to check the tray there was no water in the tray just wet in there but no water in the front at all and it was parked on a slope towards the front of the car. I was told that there were no blockages in my drains by the repair shop that did all the work.

Thanks again mike

UrS4boy

Running you should be seeing around 13.7V. Engine stopped, something like 11.5V.

GoHeels

I had an issue with my S4 when I first got it. After it rained it would soak me when I backed out of my parking spot. I had to squeeze the "nipples" on the end of each rear drain hose behind the rear tires, which let some old junk out. They were gummed up from being old, but messing with them fixed my problem.

BB1995S6

Mine says 11.9 now and it shows 13.8 v right after I started her.. I'll check the tubes but I think they are clear, my issue is with how munch is acceptable water coming past the sunroof mine pours in the gutter and then drains.

Martc

Hi,

I have a slightly different problem, on my Urs6 with a steel sunroof the sunroof seal does not stay in place which causes excessive cabin noise. The seal itself is in very good condition but seems to be oversize and does not hold it self well to the front part of the panel, so when you open the sunroof the front of the seal drops away.

To me it looks like there are places where clips should be situated to hold the seal in place, although I cannot see anything on EKTA to confirm this though?

At the moment I have blue tack holding it in place where I think there should be clips, it works but is not ideal at all.

Should there be clips or is it time for a new sunroof seal?

Thanks!

UrS4boy

I don't see anyclips mentioned either so probably time for a new seal (or use some silicon caulk in the grove of the seal to hold the wayward seal section in place.

Martc

Thanks - what I thought.#

I just wondered if someone has had one apart and could confirm no clips to help the seal grab onto the panel better - reason I ask is that I have had occasion where Audi has missed off parts from their drawings before