Unblocking drains DEFINITIVE THREAD
 

Right then, car has just passed the MOT for another year which is all good, however I’ve got the car booked in for Friday because the passenger carpet was damp and there’s a damp smell in the car. The foam underneath was quite wet but not utterly sodden so may have just caught it before I get a swimming pool.

So, it looks like one or more of my drains is blocked. I’ve looked at the common faults thread on here and found the Quattroworld link detailing the drains: https://forums.quattroworld.com/a8/msgs/18945.phtml

Forgetting Botang’s hole, how many actual drain points are there? Exactly where are they? And what colour are they? Are there 5, 6, 7, 8 drain points??? And which nipples can be totally removed and which ones need to stay (and just be cleaned). I ask this because there doesn’t appear to be a DIFINITIVE drains guide anywhere. Yeah, sure, I’ve searched exhaustively on here and found myriad posts about water ingress but they’re all referring to assorted and differing drains.

Realistically, how much labour would checking/unblocking all the drains cost?

I wanna nip this in the bud (or is that nip this in the nipple, if you will..:tuttut:). Maybe get a nippleectamy or 3 lol. However, my mental health hasn’t been fantastic recently, it’s freezing cold and damp and I don’t have a nice warm garage either - hence booking it in.

My local guy is pretty good but I wanna go in there armed with the knowledge of all the points so he can do the work. I wish to high heaven that I lived nearer to D2Doctor or Unit20 or the like but unfortunately I’m nowhere near - I’ve used this chap a couple of times and he’s actually pretty good. He sorted a tricky problem on my other car and didn’t charge me the earth to fix it.

Forgive all the questions - but there is unclear info - for example in the Quattroworld post above, it mentions more than 2 sunroof drains, front and rear of the vehicle - so does that mean there are 4 for the sunroof??? You get the idea why I’m asking.

If there isn’t a definitive drains thread then I really do think it’s high time there is one, i.e. this thread - because blocked drains on this car are are so ridiculously common and problematic.

Thanks chaps and chapesses :)

I can't give a definitive answer on exactly how many drains there are (or additional leak points such as Botang's hole, boot grommets, rear light clusters etc.) but I can say that they never, ever go away.

Whatever you do something, somehow will find a way to block the drain and cause problems, so be prepared to regularly clear them.

I'll stick what little I know on my next post for others to then copy/edit to accumulate a single list in one post.

For the record I have no issues with sunroof drains or Botang's hole. But I never ever open my sunroof......

List of drains and water ingress points (please copy and add/expand/explain):

1. Orange drains from aircon condenser tray, one each side of the transmission tunnel behind interior trim (which needs care and knowledge to get out undamaged)
2. Scuttle drains under windscreen scuttle panel. Easily blocked by leaves, difficult to get at. IMHO it's not really the big nipples that are the problem, but higher up in the tray.
3. Sunroof drains
4. Boot cable grommets, especially on right side. MJ has a solution. +++
5. Seals around rear light cluster in boot lid
6. Rear numberplate (not sure about this one, but I've seen people seal there)
7. Small drains under bonnet, either side close to the wing panels.

List of drains and water ingress points (please copy and add/expand/explain):

1. Orange drains from aircon condenser tray, one each side of the transmission tunnel behind interior trim (which needs care and knowledge to get out undamaged)
- Full instructions on how to do this can be found at the following link: http://www.audipages.com/Tech_Articl...tordrains.html
- Ensure you have a large enough container to capture the water when you remove these, and prior to refitting, soak them in hot water to make them more pliable. They look like this:

http://forum.a8parts.co.uk/attachmen...1&d=1607431661

2. Scuttle drains under windscreen scuttle panel. Easily blocked by leaves, difficult to get at. IMHO it's not really the big nipples that are the problem, but higher up in the tray.
- hidden under the HVAC unit and best accessed using something like a piece of copper brake pipe to get it angled correctly to wiggle around, and it exits both sides of the transmission. A combination of hot water and kitchen drain cleaners used to clean them, and then flushed again with clean hot water. Location and image as follows:

http://forum.a8parts.co.uk/attachmen...1&d=1607432583
http://forum.a8parts.co.uk/attachmen...1&d=1607432852

3. Sunroof drains
- Four in total, one at each corner of sunroof frame. Plastic tubing is very pliable so extreme care when cleaning these out. Front ones exit at the base of the A-pillar (you can see them when you open the door), and the rear ones exit behind the back wheel. Illustration of layout as follows:

http://forum.a8parts.co.uk/attachmen...1&d=1607431972

4. Boot cable grommets, especially on right side. MJ has a solution. +++
- Link to specific thread about these - http://forum.a8parts.co.uk/showthread.php?t=15456

http://forum.a8parts.co.uk/attachmen...1&d=1579467305

5. Seals around rear light cluster in boot lid
6. Rear numberplate (not sure about this one, but I've seen people seal there)
7. Small drains under bonnet, either side close to the wing panels.
- About two inches long and exit at the back of the wheel arch. Location and image as follows:

http://forum.a8parts.co.uk/attachmen...1&d=1607432071
http://forum.a8parts.co.uk/attachmen...1&d=1607432356

8. Botang's Hole - Even though it's not a 'genuine' drain, it has caused lots of issues so should also be addressed. The following link shows very detailed photos of its location: http://forum.a8parts.co.uk/showpost....2&postcount=16

A few points about the scuttle and aircon condenser (orange) drains:

The orange drains, in theory, only ever get totally clean water so shouldn't get debris. In practice the tray is open to cabin air so some dust/debris gets in. BUT if the scuttle drains overflow muck from there gets in somehow making it much worse. The tray holds several pints!

Cutting the tips off the orange drains "cross", so they're a mm or so open seems to help reduce blockages.
In an emergency the passenger side trim panel is much easier to get off so clear that drain first. The drivers side needs the knee panel removing first which is a recipe for broken fixings.

When refitting (I dip in boiling water!) the two smaller collars go either side of the transmission tunnel metalwork, push through with fingertips until it feels fully seated.
There is thick insulation inside the cabin that the larger collar seals against. The cross end obviously points down out of sight.

I find that ensuring the scuttle cover is precisely fitted to the base of the windscreen and cleared out regularly reduces the frequency of blockages.
If it doesn't fit snugly debris, leaves etc. just wash down the windscreen and straight into the drains.
You can peer into the tray (under the HVAC air intake unit, from nearside is easier) with a torch to check for water build-up.

I use a flexible plastic pipe and "suck and blow" down it to agitate the debris, after first syphoning off any deep water then adding hot water and detergent.
In my case the blockage seems to usually be in the tray, once that's softened by heat, detergent and agitation it "whooshes" out through the pipes.
I think once warm the exits there are large enough and far enough down that the flow just goes straight through. No need to trim them.
(Though they are almost totally inaccessible anyway unless the engine is out!)
Preventive maintenance of very hot water and detergent flushed through regularly I heartily recommend. I've got an indoor watering can with a very long spout that holds a couple of litres and does the job well.

yey for this thread, I've been reading loads of threads on blocked drains and until know was none the wiser, keep it coming

As to the drains at the back of the front wheel arches, I removed the rubber ‘teats’ years ago. As an Audi indy mechanic advised - it’s not an amphibious vehicle! I kept them in case there was any issue, but it seems to reduce blocking significantly.

Fantastic response guys +++ TYVM

Roughly how long should each set of drains take to inspect/clean? Remember the car is going into a proper garage workshop with carlifts, airlines etc.

The time consuming drains are the aircon drains. The transmission tunnel covers have to come off, and there is a cunningly hidden bracket on the driver’s side which, if you don’t know it’s there, is easily broken. I had to make a new bracket for my S8 at a previous ham fist had broken it. With an air line, the others should a doddle.

For a pro mechanic, I’d guess at no more than 3 hours, but there are more experienced folk here who could give a better estimate.

The orange drains need knowledge and care to get the trim out, someone who'd never done it before would need detailed instructions or risk irreparable damage!
MJ can probably do both well inside an hour! It would take me that long just to do the passenger side and I've done it several times.

Same here, I made a bracket fixed to one of the air vents in the end. Better than the original long fragile plastic tab.