[Socket]

DIY - Fixing a blocked E92 sun roof drain

Ever got into your car only to find the footwells are full of water??
Nothing worse

While there are a number of things that could be the source of the leak, if you have a sunroof, it is quite common for a blocked sunroof drain to be the cause
Especially if there is a large volume of water in a short period of time or if the flooding is only on one side of the cabin....

Other signs are wet A pillar or a wet headliner where it meets the A pillars. This is because when the sunroof gutters fill with water and have no where to drain, they overflow into the headliner and the water runs down the A pillars, behind the dash and into the floor.....resulting in a flooded a cabin

The sunroof has a channel (gutter) running around it, which collects water that leaks past the sunroof seal. The gutter has a drain hole in each corner (left and right front & left and right rear) (see pics 1 to 3)



A blockage can occur in any of the four drains or at the top or bottom of the drain hose (although the blockage usually at the bottom of the drain hose (under the car) as there is usually more grim and dirt in this area then at the top

To test to see if you have a blockage, carefully fill the sunroof gutter with water and see if it drains away. It should not remain full or pool for anything more then a few seconds. A clear drain hose will drain the water very quickly, so if the water is not draining away immediately, then you have a full or partial blockage ..

[Socket]

The drain hole connects to the drain hose via a rubber connector under the corner of the headliner. There is no need to drop the headliner unless you want to check if the rubber connector is properly seated or something.

To do this simply remove the sun visor and clips, and the grab handles above the window, then you can drop the headliner enough to see the connector. But as I said there is no need to do this

The hose from the drain hole is very short (3 or 4 inches) before it does a 90 degree bend down into the A pillar. This means if you are trying to push a wire or something to unblock the drain hose from the top, it will only go in a few inches, so don't bother trying to get past the 90 degree bend

(see pics 4 to 6)

[Socket]

The drain hose follows the A pillar, under the kick panel and exits under the car as a drain point. It is under the undertray, close to the jack point.

There is no need to take off the wheel liner, but you will need to drop the under tray around the jack point, to get the the drain.

The drain has a rubber cover (which is often missing) and is fluted inside.

(see pics 7 to 9)


It is usually blocked with dirt and mud, so just use a large cable tie or something solid and flexible to push inside the drain hose and clear whatever is causing the blockage.

I then used a large syringe filled with hot soapy water and squirted it into the top of the drain hose via the sunroof drain hole (maybe 10-12 times) until I was happy the hose was cleared.

Final check was to carefully fill the sunroof gutter with water to see if it drained properly.....

Then , simply put the undertray back together etc and go dry out the car

Hope this helps someone

[m_thompson]

The end of the drain hose on our E91 was clogged. I was able to clean it out with a piece of wire.

[Socket]

Originally Posted by m_thompson

The end of the drain hose on our E91 was clogged. I was able to clean it our with a piece of wire.

Nice work Half the challenge is finding the drain

[m_thompson]

Originally Posted by Socket

Nice work Half the challenge is finding the drain

I found the drain after I disassembled half of the car.

[Socket]

Originally Posted by m_thompson

I found the drain after I disassembled half of the car.

Before of after you read this?

[m_thompson]

Originally Posted by Socket

Before of after you read this?

Months before.