Water in Front Footwell (Cleaning Air Intake Plenum and Sunroof Drains)

[M5forPhaeton]

I had a problem every time I went through a car wash...yes, yes, I know, I should handwash, but I just can't every time. That problem seemed to have vanished, but I'm wondering if it's related. ANYWAY, minding my own business, a little rainstorm came along and my engine light came on, followed by the transmission going into emergency mode. A little investigating revealed that water is coming into the front passenger footwell. I'm talking enough water to soak the carpet. Thinking it was a fluke...I shop vacuumed the water out and looked for the source. Couldn't find it. Ok, everything was back to normal until it started raining again...I took another careful look and it seems that water is somehow running in where the front right passenger foot would rest (if there was a foot rest there).

Any ideas? Is this something that would be covered under warranty?

Thanks!

AND for my Christian friends...Merry XMAS (and non-christian friends too).

[PanEuropean]

Hi Kelly:

I can think of two possible causes for your problem. One would be debris (leaves, pine needles, stuff like that) blocking the water drains that are just below the base of the windshield, and the other would be a plugged drainline from the sunroof.

I'm not sure if you want to investigate the problem yourself, or take the car to your VW dealer. It's 50/50 whether or not debris under the hood would be considered a 'warranty' issue or not, so, you might be better off to do a little investigation on your own first. Here's a quick how-to:

Cabin Air Intake Plenum

Air is drawn into the heating and cooling system for delivery to the cabin via the large hole that you can see in the first picture below. This is the hole in the middle of the car, directly behind the engine. That hole has (or should have) a neoprene gasket all around it, very similar to the door gaskets. If that gasket is missing, then you have found your problem.

If that gasket is there and it does not appear to be damaged, have a look at the areas on either side of it. See if there is any debris present on top of the black plastic covers. If the top of the covers are both clear, remove the cover (it is fairly easy to do) and inspect underneath. If you have a garden hose handy, run water into either side of the area directly in front of the windshield - but don't run water into the air intake hole in the middle! See if the water runs out freely - it should drain out onto the ground pretty quickly.

While you are in there, have a look at the two pollen filters that are mounted on the underside of the hood - check and see if they are wet. If they are wet, that is pretty good evidence that water is pooling up in the areas on either side of the central air intake.

Cabin Air Intake

If everything appears clean on first inspection, remove the large plastic cover that runs across the back of the engine compartment, over top of the cabin air intake. I have posted instructions below. The 'trick' to removing this cover is to first unlock the four fasteners, then lift the FRONT edge of the cover, then pull the cover forward about an inch as you lift it up.

There is also a fully illustrated post explaining how to remove the plenum chamber cover here: How to remove the Plenum Chamber Cover

Removing the debris screen
Twist the four fasteners a quarter of a turn each

Example of Debris under the Cover - in this case, pine needles

It helps to know where the retaining hooks on the bottom of the debris screen (shown above) are before you try to remove it.

Once you have removed this cover, inspect for debris in the wells on either side of the cabin air intake (the middle hole). Perhaps try adding water to the side wells with a garden hose, and observing under the car to see if it is flowing out at an acceptable rate of speed. At the same time, inspect the second gasket that seals the bottom of the debris screen to the perimeter of the cabin air inlet (in the middle of the car) to make sure there are no problems with it.

When you re-install the debris screen, pay attention to how you arrange the rubber flaps at each end - this matters. Note how the rubber flaps fit OVER the big cover, as seen in the photo at the very top. Also, be aware that the raised lip on the aft edge of the debris screen fits under the cover that is attached to the base of the windshield. It is fiddley work to get the cover re-installed, so, take your time and take it easy. There is a way to get it in there without force - it just isn't obvious, that's all.

If you have not discovered any problems in the air intake area, then the source of your leak is likely one of the drain tubes that run from the sunroof down to the bottom of the car. There are four drain tubes in total, one in each corner of the sunroof assembly. They run down the two front A pillars and exit just behind the front wheels, and also run down the two rear C pillars and exit into the upper wheel well area, behind the rear wheel well liners.

Three things can (commonly) go wrong with these drain tubes on any car that has a sunroof:

1) Tube opening gets plugged by debris up at the sunroof itself.
2) Tube comes apart somewhere between where it leaves the sunroof and where it exits the bottom of the car.
3) Opening on the bottom of the car gets blocked, so water backs up the tube and leaks out a joint somewhere.

I have no experience troubleshooting sunroof leaks. The best suggestion I can offer is to open the sunroof glass fully, then get a watering can with a narrow spout and pour water into each side of the sunroof frame assembly, outboard of the hole in the headliner. In order to test all four outlets, you will probably have to find a hill somewhere and park the car nose down and nose up, to cause the water to run out the front and rear outlets on each side. However, if you are getting water infiltration into the front passenger footwell, that kind of suggests that there may be a problem with the front passenger corner tube.

I have posted an illustration below that shows the position and routing of the four water drain hoses in each corner of the Phaeton sunroof. Be aware that the rear two hoses drain from the very aft corners of the sunroof frame - in other words, about two inches outboard and to the rear of where the back of the glass panel will be when the sunroof is open. So, you won't be able to see the drain holes that lead to those two rear hoses when you look in from above... hence the need to do a function-check with a watering can.

My guess is that your problem will be found where I have put the red arrow in the illustration below... the hose has probably come out of the socket in the rubber piece that fits into the engine compartment bulkhead. Although it is fairly easy to get access to the outlet of the front two drain hoses (some further disassembly is required, which I do not recommend you try yourself due to the risk of breaking the windshield - see this post for full details: How to remove the Plenum Chamber Cover), it is a nuisance to get to the two rear outlets - you have to remove the rear wheel and then remove the rear wheel well liner. See the photos below for locations of the sunroof drain outlets.

Sunroof Drain Design Illustration

To clean the drain lines, you run a thin, flexible cable (a speedometer cable with a 2mm ball glued on the end is perfect) down the hoses from the sunroof - or, up the hoses from the drain hole, whichever is easier. However, if the tube has come apart from the grommet assembly where it passes through the firewall (front) or body structure (rear), cleaning won't fully solve the problem - you will need to do more disassembly of the interior of the car to get access to the rubber grommet that the drain tube terminates at, where it passes through the metal bulkhead. That level of disassembly is beyond the scope of this reply.

Hope this helps...

Michael

Location of Sunroof Water Drain - front of car

Location of Sunroof Water Drain - rear of car
This is an excellent picture for the purpose of showing how the drain hose mates with the grommet. The design is similar at the front. Slight disassembly is required to get access to this, although it is faster and easier to get access to the rear one.

[PanEuropean]

Here is a photo that shows the detail of how the sunroof drain tube fits into the bulkhead grommet. Although the blue tube is attached to the rubber grommet with a solvent that actually melts the two components together, it is possible to 'blow them apart' with the force of some high pressure car wash sprays. It's not a design problem, it's just basic hydraulics - if there is a slight blockage in the tube, the tube fills up with (non-compressable) water. The car then moves from the water flood area of the car wash to underneath the high pressure blower to be dried off, and the full air pressure of the drying blowers is transmitted to the end of the drain hose by way of the water that has accumulated in the (partially blocked) drain. This is what blows the fittings apart.

It is reasonably easy to get access to the rear tube and bulkhead grommet - all you have to remove is the rear seatback. It is a real nuisance to get access to the front ones - you have to remove the dashboard.

Michael

Lower end of sunroof drain tube (rear)

[fuse]

Mine had water in the passenger footwell-it turned out to be something loose in the cowl area. Fixed by the dealer and dry ever since.

Archival Note: See this thread for the explanation about how to solve "something loose in the cowl area": Water Leakage into Cabin by way of Electrical Box

[M5forPhaeton]

Tears of joy are streaming down my face. There was so much debris (pine needles, dirt, misc junk) behind the screen that I must say that's the culprit. I've cleaned it all out and will cross my fingers!

You're too good!

Best,

Kelly

[PanEuropean]

I'm happy to hear that solved your problem.

Michael

[PanEuropean]

Just a follow-up post:

There is a rather large drain (it is possible that there may be two drains, one on either side, I am not sure) to allow water to escape from the cabin air intake plenum. It is entirely normal for water to enter this plenum - you will get water in the plenum every time it rains, and every time you wash the car. Normally the water flows to the lowest part of the plenum on either side of the central air intake (pictured above), then escapes out the rather large drain valve that you can see in the pictures below.

The drain valve is about one inch (2.5 cm) diameter, which is more than large enough to allow small bits of plant and leaf matter to escape. But, if you park in an area that has lots of conifer trees (trees with needle leafs), it is possible that pine needles will get stuck in the opening, and then other debris will form around the pine needles and plug up the drain. If this happens, then you may need to look at the exit point of the drain and consider cleaning it there, in exactly the same manner that you would clean a water downpipe from the roof of a house.

There are three pictures below that show you where you can find the air intake plenum outlet. This is quite easy to find when the car is lifted up if you know where to look for it.

Michael

Cabin Air Intake Plenum Drain Outlet

<

<

[PanEuropean]

Another possible way to get access to these two drains is to remove the front suspension, the engine, transmission, and driveline, but this is time-consuming to do and should only be considered as a last resort.

Getting access to the Plenum Drain - the hard way

[GAIJIN]

same problem.

Tried drainlines bellow windshield. didnt work. water everywhere

now will be trieng sunroof drainlines.

Will keep you updated.

thanks Michael and Kelly

Regards

Zahid

[GAIJIN]

what if i try to use a compressor and try to force everything out where it came from with air???

[PanEuropean]

You would probably wreck everything.

[GAIJIN]

ok then. i will be delicate

[GS340]

I've been dealing with this issue for a while now, april 08. While driving one day with the AC on I heard this sound like a vacuum sucking something up and now that something is stuck behind the defrost vents.

Anyone have any ideas how to remove whatever is suck there. I've been to the dealer and they told me this issue isn't covered under warranty and they would have to remove the entire dash... Several thousands in labor and they said they aren't sure if the dash would even go back in correctly. They basically refused to look at it.

Sometimes the auto climate control turns on the defroster and hear that something blowing around in the vents. I can't take it anymore.

Thoughts? suggestions?

[Waterwerkes]

I've got the same issue with my car. I find that if I drive with the sunroof open, it shakes and rattles around in there... I know just how annoying it is. I'm just in the process of moving my shop to a new location. As soon as it's done, I'm going to try to remove this nuisance. I don't think the entire dash has to be removed. I have a feeling I'll be able to blow it out backwards. If anyone else has a different solution, please let us know.

[car_guy]

I don't understand how an object could get past the dust/pollen filters unless they are not present. I would confirm that they are in place. Maybe a vacuum used at their location could pull the object out.

I just received a new set of filters to install when I do my 60K service. They ain't cheap! The plugs are pretty pricey as well, but at least you only do them every 60K.

Steven

[PanEuropean]

Quote, originally posted by GS340 »

Thoughts? suggestions?

Yes, my suggestion is that you check the table of contents first. There is quite a detailed post listed there entitled "Cleaning Air Intake Plenum and Sunroof Drains". I have appended your inquiry onto the end of that post.

Michael

[GS340]

Bill Britt VW was able to clean out the leafs in the AC system. Leafs were getting sucked in around the wiper arms. When I dropped the car off the we noticed right away how the leaves were entering the system. There was one leaf half way in around the wiper arm.

the leafs where stuck to the heater core which required removing the blower fans but after they were out of the way it was easy to clean up.

They also tried to clean out the ducts/vents with a vacuum but no success...

The tech mention this wasn't the first phaeton he has seen with this issue. Last year a piece of foam insulation from the AC system broke off and got sucked PAST the heater core and got stuck INSIDE the dash. He had to remove the dash to get access to the ducts. Good thing the dash removal was covered under warranty..

Modified by GS340 at 3:12 AM 11-3-2008

[GS340]

Quote, originally posted by PanEuropean »

Yes, my suggestion is that you check the table of contents first. There is quite a detailed post listed there entitled "Cleaning Air Intake Plenum and Sunroof Drains". I have appended your inquiry onto the end of that post. Michael

Michael, I did... I even found copies of the manuals online and tried to clean out the vents myself. My issue was the leafs got past the blower fan and where inside the AC system itself. Not something I could remove and clean out myself. I was REAL lucky the leafs were stuck to/inside the core vs going around the core. Then the he would had to remove the dash to get to the leafs.

You should take my post out of this thread since my problem was inside the dash vs just cleaning out the junk around the debris screen...

My issue was when the AC/Heater was on you could hear stuff blowing around INSIDE the car inside the vents.

thanks!

Robert



Modified by GS340 at 3:20 AM 11-3-2008

[GS340]

On last thing.. .I suggest everyone check their debris screens. Make sure the screen is positioned correctly and secure. If anything gets past the screen REMOVE it immediately. Its much easier to remove the screen vs the blower fans or worse the entire DASH!!!!

[PanEuropean]

Archival Note: Related discussion - Water ingress to cabin from the air conditioning system. But, the possibility of water getting into the cabin from the air conditioner condensate drains is quite remote. Other causes should be investigated first, probably in about this order:

1) Damage to underbody of car, missing drain plugs on underbody of car - see this post: Lifting the Phaeton on a Hydraulic Lift - Precautions

2) Blocked drain from air intake plenum (the big orange drain) - the post you are reading now.

3) Blocked Sunroof Drains - also described here, in the post you are reading now.

4) Electrical Box Cover not correctly installed (applicable to front passenger footwell leaks only) - Water Leakage into Cabin by way of Electrical Box

Michael

[Richard Steckly]

Many thanks, Michael. You're assistance is unmatched.

Richard

[PanEuropean]

Hello Everyone:

Apropos of the difficulty that some forum members have been having with water drains getting plugged, I thought it might be a good idea to create some instructions about how to clean the sunroof drains.

This post addresses cleaning the FORWARD sunroof drains. There are four drains in total, one in each corner of the sunroof assembly. The forward two are easily accessible. The aft two are not easily accessible because they begin "one sunroof length" aft of the aperture in the roof.

Anyway - to clean the forward drains, open the hood, then remove the large screen that covers the area behind the engine. The passenger side sunroof drain is easily visible and easily accessible, although you will probably need a flashlight to find it the first time. The driver side drain is more difficult to get at... so, disregard the driver side drain for the moment.

Remove the screen aft of the engine compartment

Where the drains are

What the drain outlet looks like (forward passenger side shown)

Looking in from the top of the car, inspect the tray surrounding the sunroof. Remove any debris you find in it. Look for the drain hole in the tray, which you can see in the picture below. Make sure there is no debris blocking the drain hole.

Forward Passenger Side Drain Hole

Then, using either a garden hose or a watering can, pour some water into the FORWARD PASSENGER SIDE corner of the tray. Observe and determine if the water flows down the hole quickly, or if it just puddles up and stays there.

If it does not flow down the hole quickly, reach in and "massage" the tip of the rubber outlet on the passenger side of engine compartment. Chances are that it is just stuck together from heat, dust, lack of use. Water should start to flow out of it after you massage the end of the rubber tube.

Once you get water flowing, squirt some household dish detergent into the roof tray and add some more water to rinse this dish detergent down the tube. Watch for evidence of the detergent coming out at the other end of the tube. The detergent will clean out any dust, pollen, etc. in the tube.

Now move over to the driver side of the car. It is quite difficult to get access to the bottom end of the drain outlet on the driver side (you need to remove the windshield wipers and the plastic trim strip that runs across the bottom of the windshield to be able to get your hand in there - see this post: How to remove the Plenum Chamber Cover). But, rather than doing all that disassembly, just wait until the water runs out of the passenger side drain (leaving you with an empty water tray up at the roof), then, aim your garden hose into the driver side drain and give it a good blast of water. That will most likely blow the other end open.

Cleaning the driver side drain hole

Now fill up the water tray surrounding the sunroof aperture and confirm that water drains out of both sides (left and right) at the front of the tray.

Once you have confirmed that the two forward drains in the sunroof water tray are functioning properly, move your hose down to the area where the other end of the drain tubes are (just aft of the engine) and fill those areas up with water. It will take about a gallon of water to fill up each side. Look underneath the car and confirm that water is flooding out the drain outlet, which is approximately in the middle of the car.

If any debris floats up (leaves, pine needles, etc.), clean it all up.

Regards,

Michael

[PanEuropean]

PS: For information about how to thoroughly clean out the water drains in the two compartments aft of the engine (perhaps something that should be done BEFORE cleaning the sunroof drains), scroll up to the very top of this page.

[PanEuropean]

Just for the record, here is a picture showing where the drain is for the forward driver side (left hand) sunroof drain.

Before this photo was taken, both windshield wipers were removed, and the plastic cover that runs across the bottom of the windshield was removed.

Michael

Driver Side (North American Car) Forward Sunroof Water Drain Outlet

[PanEuropean]

Archival Note: related posts that may be of value when troubleshooting water infiltration problems -

Water leak in cabin footwell

water leaking problem passenger footwell

[aubergine2004]

Hello -- I'm pretty sure I have a rear sunroof drain problem. During a bad storm last week, the liner material between the rear passenger window and the rear window got soaked... plus the floor gets wet.

What is my best plan of action to rectify this situation? Is there something easy I can try before taking on the rear seatback removal?

I also had some blockage in the front main drains which was solved by running warm soapy water throughout the system and vacuming the debris floating up. I guess I should try this for the rears but not sure how.

-paul

[bobm]

I think that you can get this add on from the OEM parts guy:

[Itzmann]

Had a similar one-time event while going through a car wash. This capped a period of time when the sunroof was squealing as it closed AND had ultimately developed a rather nasty rattle coming from the sunroof area.

Service technician cleaned out the rubber seal and drain channels which were plugged. Gave me a VW rubber/cleaning/lubricant compound for me to use every six months. This solved both the rattle (which was caused, incredibly enough, by the dried out and dirty rubber) and the flooding thing.

[PanEuropean]

Quote, originally posted by aubergine2004 »

What is my best plan of action to rectify this situation? Is there something easy I can try before taking on the rear seatback removal?

Hi Paul:

There is a reasonably comprehensive post about cleaning sunroof drains at this link: Water in Front Footwell (Cleaning Air Intake Plenum and Sunroof Drains). Although most of the conversation and all of the photos deal with the front two sunroof drains, the concepts are identical for the ones at the rear.

In a worst-case situation, you might have to remove a few of the fasteners that hold the forward portion of the rear wheel well liners, and stick your hand in there and 'massage' the rubber teat that is the distal end of the rear sunroof drains. It is possible that debris has accumulated at the bottom of the tubing, and this is preventing the rubber teat from opening up and letting the water out.

The photo below shows where the drain line passes through the aft portion of the rear cabin door aperture. It exits on the other side, however, we can't see the exit because of the fabric/hardboard wheel well liners installed in the two rear wheel wells. You should be able to just remove a few fasteners (Torx 25, I believe), and that will enable you to get your hand in there and feel around.

Lift the suspension system up to the highest setting before you begin work, that will increase the clearance between the rear tires and the wheel well liners.

Michael

Rear Sunroof Drain Exit Point (inside of vehicle)

[PanEuropean]

Hello Everyone:

There is an additional location in the car that could possibly cause water leakage into the front passenger footwells, The possibility of leakage from this location is remote, and this location should only be checked after you have checked for leaf debris in the air plenum under the wiper motors (far and away the most common cause of water problems), and after you have checked the sunroof drains to ensure that they are operating properly (the second most common cause of water problems).

This additional location is the two water drains that are attached to the evaporator pan at the very bottom of the main HVAC unit. There is a post that provides more information about these drains at this link: Water ingress to cabin from the air conditioning system.

On an entirely different matter, there is a very informative post about possible water infiltration into the passenger footwell via the electrical box that is under the hood - that post is here: Water Leakage into Cabin by way of Electrical Box.

So, to sum up, you have numerous possibilities for water leakage. None are design faults, the leakage is caused by either buildup of debris or failure to properly close something up or attach something correctly following service. In order of probability, here are the things to look for:

1) Leaf debris in the cabin air intake plenum (the beginning of this post explains how to locate the plenum, remove the cover, and clean out the debris).

2) Blocked sunroof drains (about halfway down this post you will find the explanation about how to clean these drains).

3) Improperly fastened cover on electrical box under the hood (discussed at this post: Water Leakage into Cabin by way of Electrical Box).

4) Loose connection of drain line to evaporator pan drain spigot (discussed at this post - Water ingress to cabin from the air conditioning system).

Michael

[Zaphh]

Hi Michael,

You forgot to mention missing rubber caps under the car...

You are absolutely correct, that should have been the first thing on the list. See this post: Lifting the Phaeton on a Hydraulic Lift - Precautions

Michael

[Brandini]

Greetings. After torrential rain last night I find myself on the forum this morning. Braking at a red light caused a small splash of water to spill out from under the rear, passenger side seat. After reading this thread I suspect the sunroof drains. Would it be possible to have the relevant images re-hosted? Thank you for all the support you provide us.

Brandini

[aubergine2004]

Michael:

Thanks for all your help on the water issue. My car is draining much better now. Reaching inside the rear wheel wells and messaging the nipples really worked.

-Paul

[PanEuropean]

Quote, originally posted by aubergine2004 »

...messaging the nipples really worked.

It takes all the self-discipline I can muster to leave that line alone...

Glad you got the problem solved.

Michael

[PanEuropean]

Quote, originally posted by Brandini »

Would it be possible to have the relevant images re-hosted?

Hi Brandini:

All the images appear when I look at this post using my computer.

It is possible that your computer's security settings are set such that your browser is not displaying images that are hosted at a third party URL. Some of the images on this thread are not embedded into the content hosted on vwvortex.com, instead, the images are hosted on an imageserver (dubfoto.com), and the message here contains a URL that points to the image at this third site.

Many 'advertisement blocking' programs work by preventing images that are hosted elsewhere than the domain you are looking at from appearing. My guess is that this is what is causing your problem.

Michael