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Matthew Ashton

Windscreen Rainwater Drainage

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This is a follow on to the long thread titled "Heavy Rain, Water Leak": 

 

 

I did a bit of a strip down of my car today to investigate the flow of water coming from the windscreen in to the engine bay on the near-side on the F10/F11.

 

Here is the Panel behind which is the yellow grommet that is causing people so much grief with wet carpets It is the panel on the left of the picture:

IMG_5914.jpg

 

This is what you find behind that panel once you remove the 4 screws and remove it:

IMG_5924.jpg

 

The first area I looked into was the grill shown on the left - water that enters through that grill goes straight down and into the yellow grommet plenum that a number of us have accessed recently.

 

IMG_5925.jpg

 

I put the camera down in this position and it comes out directly into the plenum area...

InkedIMG_3800_LI.thumb.jpg.9d4bfb6ac2450735111e3addd3959231.jpg

 

The plenum cover has been removed and the screw hole you can see next to the camera head is the top mounting screw for the cover.

InkedIMG_3802_LI.thumb.jpg.9d5c3d1fc551cec40e478b685f98c142.jpg

 

Next, I removed the wheel arch cover to look for a drain hole... And there it is, circled here:

InkedIMG_3796_LI.thumb.jpg.910df259ac434db48bd696e4c44c45b9.jpg

 

You can see some leaf debris peeping through along the left hand side of the grommet

InkedIMG_3809_LI.thumb.jpg.f222b9253d622924f25d32dfd53e6ee7.jpg

 

Now I turn to investigating the right hand grill and drain...

IMG_5925.jpg

 

I put the camera down in the area circled on the right...

IMG_5926_LI.jpg

 

So looking straight down between those 3 black pipes, this is what you get, another catchment cavity filled with leaves...

IMG_5944.thumb.JPG.f0b6718a87797669e373d5bcd369103c.JPG

 

I removed the camera and put the hosepipe down there and gave it a good blast and most of the water came out from the drain I showed you behind the wheel arch liner. With a bit of help I managed to remove most of the leaves through the drain hole.

 

Note that some water did trickle back into the yellow grommet plenum but most came out of the drain.

 

Lastly I investigated the cavity beneath the nearside bonnet hinge between the wing and the blower motor housing. I put the camera down but couldn't get a good view as to what was happening down there so I put the hose down and again the water poured out of the drain behind the wheel arch liner with some water making its way into the yellow grommet plenum.

 

I think the pipe shown here (just a hole in the bodywork on other's cars) is to drain the plenum as the water coming down from the grill/drain on the left in the first picture only goes into the plenum and needs to get to the drain grommet.

IMG_5948.thumb.JPG.a0012ffed06d0e6bbd992502b3ea283f.JPG

 

In summary, 

The grill on the left in the first picture goes straight into the plenum.

The grill on the right in the first picture goes down into a body cavity that leads to the drain grommet behind the wheel arch liner.

The cavity under the nearside bonnet hinge also goes directly to the drain grommet behind the wheel arch liner.

 

But all of the above are linked too via the hole/pipe to the lower left of the yellow grommet.

 

There is a design flaw as those leaves you see 2 pictures above are nigh on impossible to remove (they come from the grill to the right in the first picture) and will keep on flowing to and blocking the drain grommet and any leaves coming from the grill to the left in the first picture will enter the yellow grommet plenum and stay there causing havoc.

 

 

Finally, I cleaned and polished the wheel inside and out before refitting and torqued the wheel bolts to 140Nm.

IMG_3817.thumb.jpg.810b02f6ce97f04431bbf9763da6378b.jpg

 

 

 

Edited by Matthew Ashton
Updated with a description of what I refer to as the Yellow Grommet Plenum.

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Great write up Matthew.

 

I take it you used an inspection camera on a wand stick, when you say you put the camera down somewhere?

 

What are you referring to as the yellow plenum chamber? I can't figure out what that is sat in my living room not looking under my bonnet.

 

Must get a poke around mine, my dad has been querying where the water goes on his F10.

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I think Matthew means the area with the yellow grommet behind the panel we all remove Andrew. (see his first sentence where he calls it a plenum)

Edited by nashdm2

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Matthew, thanks for the in depth report, I was waiting for somebody to do this so it is informative.

 

So, the only way water will enter the plenum area is from the very top, behind the panel near the top bolt? No water could be found coming in from the white pipe and in fact you suspect that pipe is for water to exit the area?

 

If so, where is the other end of that pipe please Matthew? 

 

Also, you show another area for leaves to gather with your camera shot, is there any other way of access the bottom of that area?

 

Finally, is it easy to get the top panel off that reveals the underneath of the top two grills?

 

Thanks Matthew, plenty of questions!!!! Dave

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1 hour ago, 535i Andrew said:

Great write up Matthew.

 

I take it you used an inspection camera on a wand stick, when you say you put the camera down somewhere?

 

What are you referring to as the yellow plenum chamber? I can't figure out what that is sat in my living room not looking under my bonnet.

 

Must get a poke around mine, my dad has been querying where the water goes on his F10.

 

Hi Andrew,

I've updated the post to show the cover and the yellow grommet. This cover is accessed within the engine compartment on the near side low down on the bulkhead.

I did buy an inspection camera for this. It is attached via WiFi to the iPhone 

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16 minutes ago, nashdm2 said:

Matthew, thanks for the in depth report, I was waiting for somebody to do this so it is informative.

 

Quote

So, the only way water will enter the plenum area is from the very top, behind the panel near the top bolt? No water could be found coming in from the white pipe and in fact you suspect that pipe is for water to exit the area?

Yes, water into the plenum is from the top or from the hinge cavity which does flow into the plenum if the drain grommet is overwhelmed. I have 2 theories about the pipe.

1) it is to drain the plenum

2) It is actually the outlet from the bottom of the blower housing

 

If it is the latter, then the water drains out of the plenum in the free space around the pipe - So pipe inlet and water evacuates through the gap around the pipe. I was unable to to see this in action as I really needed about 4 hands and arms to do this.

 

Quote

If so, where is the other end of that pipe please Matthew? 

 

Couldn't see even with a camera shoved into the pipe as the camera hit a deadend.

 

Quote

Also, you show another area for leaves to gather with your camera shot, is there any other way of access the bottom of that area?

No, the bottom of that cavity seems to be a body seam so there is no way to get at it from anything other than the top.

 

Quote

Finally, is it easy to get the top panel off that reveals the underneath of the top two grills?

Easy - Remove the 3 plastic rivets with a removable centres, pull up the under bonnet seal and pull the plastic cover up - This was the easiest job.

 

Edited by Matthew Ashton

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Thanks Matthew, one other question. The drain that goes in behind the wheel arch cover, is there a grill in the wheel are cover in the same area, or, does the water/leaves make there way out from behind the wheel arch cover or is is stuck up there if there is no gap? Hope that makes sense.

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6 minutes ago, nashdm2 said:

Thanks Matthew, one other question. The drain that goes in behind the wheel arch cover, is there a grill in the wheel are cover in the same area, or, does the water/leaves make there way out from behind the wheel arch cover or is is stuck up there if there is no gap? Hope that makes sense.

 

Water coming through this drain flows down the back of the wheel arch cover and down on top of the under car covering and out from there somewhere 

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I went through all the above procedures to cure the problem of water behind the passenger seat only to find that the water was coming in past the seal inside the rear door.

 

 

Sent from my iPhone using Tapatalk

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3 minutes ago, GeeJayJoe said:

I went through all the above procedures to cure the problem of water behind the passenger seat only to find that the water was coming in past the seal inside the rear door.

 

 

Sent from my iPhone using Tapatalk

 

Did you notice any water marks on the inside of the door?

 

Did the seals look damaged at all?

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1 minute ago, Y15HAL said:

 

Did you notice any water marks on the inside of the door?

 

Did the seals look damaged at all?

 

If it is coming through the door into the car it is usually the vapour barrier butyl seal failing and is easy to tell - Just remove the inside door panel, close the door and get someone outside with a hosepipe to spray water on the closed window. If the vapour seal is leaking you will see the trickle of water coming into the car.

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No water marks at all. Only found by removing the inside door panel and pouring water on the above glass and watch the drips come through between the plastic sheet and the door frame.

I added some roofing bitumen to the seal and this cured it.

 

 

Sent from my iPhone using Tapatalk

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9 minutes ago, Matthew Ashton said:

 

If it is coming through the door into the car it is usually the vapour barrier butyl seal failing and is easy to tell - Just remove the inside door panel, close the door and get someone outside with a hosepipe to spray water on the closed window. If the vapour seal is leaking you will see the trickle of water coming into the car.

 

Simple job to take the door panel off? :| 

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13 minutes ago, Y15HAL said:

 

Simple job to take the door panel off? :| 

 

It isn't too difficult and is the best way if you suspect the door vapour seal is the culprit. Search on www.newtis.info for the instructions to remove the panel.

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45 minutes ago, Matthew Ashton said:

 

It isn't too difficult and is the best way if you suspect the door vapour seal is the culprit. Search on www.newtis.info for the instructions to remove the panel.

 

I'll have a dig round - Looks like a handy site!

 

Thanks :)

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28 minutes ago, nashdm2 said:

Its strange that so many things have moved on in car production terms, but, they still use this plastic sheet to keep prevent water coming in the car from the door. Very strange.

Simple, cheap and effective...

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Great write up, thanks Mathew.

 

The big thing for me to check is the drain above the wheel arch, if this was blocked, presumably it would explain water backing up to the yellow cover chamber.

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Good point Ian. We are assuming that the yellow chamber outlet pipe is connected to the wheel arch drain, but Matthew found a dead end when he poked his camera up the pipe. 

 

When you look at the picture of the wheel arch drain, there is not much of a drain there as it has those pipes going through it also.

Edited by nashdm2

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1 hour ago, nashdm2 said:

Good point Ian. We are assuming that the yellow chamber outlet pipe is connected to the wheel arch drain, but Matthew found a dead end when he poked his camera up the pipe. 

 

When you look at the picture of the wheel arch drain, there is not much of a drain there as it has those pipes going through it also.

 

That drain is relatively small, I could get just one finger in to coax the leaves into leaving (:rolleyes:). Any big leaf build up isn't going to come out easily.

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3 hours ago, Matthew Ashton said:

 leaves into leaving (:rolleyes:). 

 

Oh dear!:P

 

3 hours ago, Matthew Ashton said:

Any big leaf build up isn't going to come out easily.

 

Or in the case of my Senator wait till you have 11 years worth which are now black and now resemble mouldy sludge, poke them out with a big screwdriver followed by a big gush of water onto your feet!

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