Re: Audi B7 A4 Flooded Footwell

Hi thanks in advance
I have a Audi A4 02reg and I have a leak that comes into my drivers footwell.
When I say leak I mean big leak that leaves me with inches of water that rivers between my drivers footwell back rear footwell.

I've finally found the area it's coming from, after hours of checking around near the battery checking drain holes and ecu box seal and no luck, I've noticed that it comes flooding in(and I mean flooding in like a waterfall)under braking from the little footrest near the clutch pedals that's closest to the heating and venting. So I think to my self it's proberly from the heater matrix. But I'm baffled that it leaks so much and my engine coolant level had not budged once(this has been happening about a month now)and seems to much of a fierce leak to say it's the heater matrix, it's like the water is storing somewhere near where I'm guessing the heater matrix would be and when I brake it like over flows and comes running through the footrest into the drivers footwell.

I just don't know where it is coming from, any ideas people?

Once again thanks and any help would be greatly appreciated

Hi thanks in advance
I have a Audi A4 02reg and I have a leak that comes into my drivers footwell.
When I say leak I mean big leak that leaves me with inches of water that rivers between my drivers footwell back rear footwell.

I've finally found the area it's coming from, after hours of checking around near the battery checking drain holes and ecu box seal and no luck, I've noticed that it comes flooding in(and I mean flooding in like a waterfall)under braking from the little footrest near the clutch pedals that's closest to the heating and venting. So I think to my self it's proberly from the heater matrix. But I'm baffled that it leaks so much and my engine coolant level had not budged once(this has been happening about a month now)and seems to much of a fierce leak to say it's the heater matrix, it's like the water is storing somewhere near where I'm guessing the heater matrix would be and when I brake it like over flows and comes running through the footrest into the drivers footwell.

I just don't know where it is coming from, any ideas people?

Once again thanks and any help would be greatly appreciated

I've had my heater matrix go - I had a lot less water than you (wet carpet but not sloshing around) and my coolant level was noticeably going down. The main symptom which made me check if the carpet was damp was the windscreen was steaming up. What about a leaky windscreen washer pipe to the rear window? If you find what it is please let us know!


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My windscreen steams up aswell, I'm not quite sure which route the washer pipe takes for the rear washer. Do you?

In fact my car doesn't have a rear washer and wiper so it can't be that

No, sorry don't know where it goes. Can you get some of the liquid off the floor and see if it's the same colour as coolant? Also, it's not too difficult to get to the heater matrix. Take the pedal cover off the bottom of the dash on the driver's side, then you can get a small cover off the side of the matrix, 2 or 3 small bolts (I remember one is difficult to see so make sure you've got them all). You can then see the side of the matrix and where it joins the pipes going up to the bulkhead - should then be obvious if it's leaking. There is a thread on here somewhere about changing the matrix, it's possible to pull it out sideways at this point without taking the rest of the dash off.


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I don't believe it is the heater matrix as my coolant level has not dropped and the water coming through reminds me of the water that condensates of the air conditioning, I'm hooding there is a drain plug around the heater matrix somewhere that's blocked, I've checked the 2 drain beings below the battery and the brake servo and they are not blocked, also I think I'm going to check the pollen filter and make sure water isn't getting through that(I was meaning to check the filter but forgot)

I cannot see that being the matrix, it would spray out under pressure when the engine was running and it would smell terrible. Have you completely stripped out the plenum chamber including removing the battery tray and cleaning the drain under the servo?

Yes and thourghly, they are not blocked, also under the vehicle I can see the drain plugs are free and not blocked at all, is there a drain bung under the centre console for the air con to drain out of?

Ok. Good luck. Let us know if you solve it. On some cars I've had there has been a drain for the air-conditioning which dribbles a bit of water on the road when I park. Haven't noticed it on the Audi though.


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