F10 Windscreen Drainage and Yellow Grommet.

[Andrew]

If you have water sloshing around in the passenger footwells in your F10, F11 or F07, then have a read of this post. 

All these versions of this generation of 5 Series have identical means of draining the water from the windscreen through various ducts, a plenum and rubber flap valves in and around the bulkhead and both wings to allow it to escape from the car. 

The reason for the water in the cabin is the scuttle drains blocking up from detritus from leaves etc building up and blocking the drains.  With water being a pesky thing it will then find the path of least resistance and make its way into the cabin and on the UK versions and other right hand drive models this is via the dreaded yellow grommet or yellow peril as its known.

The yellow grommet is needed to seal the bulkhead on right hand drive models where in left hand drive models the steering column would pass thru the bulkhead.  As we drive on the correct side of the road, our right hookers have a grommet to seal this up so this yellow grommet problem is only an issued on right hand drive models.

In the picture below is the bulkhead pressing and circled is the hole that on the right hookers is plugged with the yellow grommet.

 

 

 This is then protected by means of a cover which needs to be removed to access the grommet, but we'll come back to that problem.

This is how I cleaned out my scuttle drains and replaced my yellow grommet as I had notice it deteriorate over a couple of years.

Tools needed.

Trolley jack and means to support and secure the car

17mm socket and breaker bar for wheel bolts

Torque wrench for tightening wheel bolts to 140Nm

Hammer and small drift

Plastic trim tool for removing expanding rivets

8mm socket for wheel arch liner bolts

Torx T30 bit

Ratchet for above

Hook tool

Garden hose and scrubbing brush

Parts needed

Yellow Grommet 51719151866

Expanding rivets 51161881149

 

Water that runs off the windscreen is directed to drains in each inner wing located under the bonnet hinges via the windscreen wiper scuttle panel. 

On the offside the water is directed into a scuttle pan under the brake servo and exits via a rubber flap valve mounted in the floor of the scuttle pan.  This discharges water onto the back side of the wheel arch liner and runs down the curve of this to discharge to the ground via some holes in the liner.  To make sure the flap valve is clear, jack up and remove the offside front wheel and remove the liner.  The liner is fixed to the outer wing by means of three expanding rivets, picture 2.  Drift the centre of these expanding rivets out to allow the liner to be freed from the outer wing.   Have some spare ones in case you lose the centre part.

The rest of the liner is held on with 8mm hex head screws and one other plastic rivet, this has a mushroom head which need to be pulled out to free the fixing using your trim tool.  There are a couple more hex head screws on the underside of liner that need to be accessed from under the car.

Once you have the removed the liner you are faced with this. 

The flap valve you need to clean is fitted to the underside of the scuttle and is just above the corrugations in the windscreen washer bottle feed pipe.  Pull this out to give it a clean and make sure the flaps are pushed inwards so they are free to move.

Gently aim a garden hose into the scuttle pan from beside the offside bonnet hinge and watch all the detritus leave (pun intended!) via the hole. I gave the flap valve a clean with engine degreaser and a brush. To allow me to correctly seat the flap valve back in the base of the scuttle pan I had to unclip the washer bottle feed pipe from the bottle to allow the pipe to move slightly to get a bit more room.  Refitting is reversal of removal and torque wheel bolts once back on the ground to 140Nm.

The nearside scuttle pan flap valve is in some ways easier to access but the brake pipes also pass through the flap valve so you cannot completely remove it from the car.  If you look carefully at picture 5 you will see water trickling from a bolt hole in the liner.  Hold that thought!

Remove the wheel arch liner in the same way as the offside.  In the next picture you will see the flap valve above the brake line junction block, the bolt hole mentioned earlier above it and loads of muck on the back side of the liner, this had been blocking the drain holes in the liner and forcing the water to travel on the underbellies and exit the car in front of the rear wheel.  It should not be doing that!

All the muck has built up on the bottom rear edge of the wheel arch liner and has blocked the drain holes and water was then flowing along the top of the underbellies and exiting the car in front of the rear wheel. 

It shouldn't be doing that is that's just creating a damp/wet environment for corrosion. It was this torrent that first alerted me to the problem of the blocked wheel arch liner drains.

Disturbing the flap valve on the nearside, dislodged a couple of litres of water trapped in the nearside scuttle pan, hence the trickle of water from the bolt hole seen above.  The flap valve was blocked and a depth of water had built up enough to come out the bolt hole above the flap valve. That is not good!

Tease out the flap valve from its seat within the scuttle pan and clean the detritus and bio-film that has accumulated on it.  Make sure the flaps open outwards

 

Again, hose out the scuttle pan with a garden hose pointed in to the scuttle pan, next to the bonnet hinges.

When relocating the flap valve, make sure the small white pipe is jutting through the flap valve, I think on my car anyway, this is a drain point from the heater blower unit above.

Again, put it all back together the way it came out and make sure there is nothing hindering the flap valves from opening.  Refit the wheel, lower to the ground and tighten the wheel bolts to 140Nm.

On the nearside there is a small plenum to channel water from the centre of the windscreen scuttle panel to the nearside flap valve we’ve just cleaned out via a small square hole in the inner wing above the chassis rail. Over the yellow grommet location described above there is a protective cover which is secured with four Torx bolts creating a plenum. This plenum is in front of the yellow grommet and it can get blocked up with debris so much so that water is prevented from escaping to the nearside scuttle and builds up against the grommet.  It can then seep around the grommet if it is in poor condition, into the cabin, wetting the carpets and you are in a world of pain.

To gain access, open the bonnet and look towards the bulkhead, follow the nearside chassis rail back as far as you can see until you find the plenum cover, seen just beneath three heater hoses and a red battery cable.

Using a Torx T30 bit, unscrew the four bolts holding the cover in place.  Two bolts are into the bulkhead and two are into the inner wing and chassis rail.  Picture 10 shows three of the four bolts. Top right hand corner, hiding behind the red cable, is the bolt into the inner wing which is located at an upwards angle.  Below that is one into the chassis rail and to the left of that one, is one of two bolts into the bulkhead.  Out of the ne next picture ,to the top left you will find the second of the four bolts into the bulkhead. It can be seen in picture above.

Note the staining above on the joint between the bulkhead panel and chassis rail...

These bolts have thread lock on them, so a bit of force is needed initially to get them out.  The cover needs to drop slightly and then moved towards the engine to disengage a locating dowel from the chassis rail.  Once removed, you may not see any debris, or you may be greeted by a pile of compost!

I was greeted by a pile of compost that had lain undisturbed for just over 5 years. I cleaned out the debris and the area around the yellow grommet, the yellow just visible under the dirt!  I repeated this exercise a year later in 2019 and was met with considerably less debris.  I had cleaned out the nearside scuttle drain between these dates which helped.

In the year or so between the two pictures above I could see that the bottom edge of the yellow grommet was starting to deteriorate.  I decided to replace it in due course and a part was ordered from BMW. The part number of the yellow grommet is 51719151866 “Yellow grommet steering cover” and was less than £30, a small price to pay to keep things dry.

With a bit of spare time during COVID 19 lockdown I grabbed my replacement yellow grommet and set to work.  The cover was removed for a third time, not so much debris as last time, my cleaned out nearside scuttle drain is obviously working.  Standing parallel to the wing, grasp the grommet with your fingers and pull it out.  To get a bit more purchase as it was putting up a bit of a fight, I hooked a pick tool under the lowest edge of the grommet and pulled it out, breaking a couple of clips in the process. Oh well, it’s out now and I have a new one to go in.

The lower edge of the grommet can be seen showing the deterioration compared to the new one.

Clean up around the hole and push the new grommet until it clicks into place.  It will only go in one way. 

It is difficult to appreciate from the picture above, but there is a small square hole in the inner wing which leads to the nearside scuttle drain, make sure this hole is clean as this is where the water exits the plenum into the nearside scuttle pan and then out of the car via the flap valve.  Clean the backside of the cover and refit.  To aid refitting, the top of the cover sits in an ‘n’ shaped slot in the underside of the rubber grommet surrounding the heater hoses and battery cable. This grommet may have moved slightly when you removed the cover.  Take your time lining it up, the bolt that goes up into the inner wing at an angle is the trickiest  I used a small screwdriver to help line things up.

Now that you have cleaned out both scuttle drains and the plenum in front of the yellow grommet or “yellow peril” as its known due to the number of wet carpets reported, your 5 Series should hopefully remain dry.  However, I would recommend cleaning out these drains every year or so to keep things dry.

 

Cover removed in 2021 showing tide line and debris build up.

But the new grommet now in for a year still looks healthy, despite some debris building up.

 

Debris building up after another year in June 2022.  Proves its worth cleaning out each year to keep it healthy.

From my article in Car Mechanics Magazine April 2021.

[Kopfjaeger]

Great advice. My F07, coming up to its 6th anniversary has probably never had this checked. I'd heard about this before, but not seen such a detailed write up. I was hoping my car dudn't have the yellow peril. If its dry this weekend and not cold, I might see if I can check mine.

Based on the crud I removed from the plastic/ rubber trim panels,around the rear lights last year, this is probably overdue.

[Counter Of Beans]

I mentioned the yellow grommet issue to the BMW specialist who serviced my F10 (2015 535d) recently.  He'd never heard of it, and looked at me as if I was a bit potty.  This makes me wonder how common an issue it is, so I had a go at removing the plenum cover thingy in order to assess the grommet's condition.  I just couldn't manage to remove the bolt that goes into the inner wing, mainly because I couldn't see it!  The other three are easy enough.

Any tips for getting access to that bolt near the red wire?

Would it make sense to drill a hole in the plenum cover so that water could drain out that way?  What function does the plenum cover serve anyway?

Finally, is there an easy way to tell if one's 'grommet drain' is working properly - perhaps by pouring water coloured with food dye onto the windscreen scuttle?  I haven't had any damp carpets at all, so I imagine it's OK just now; it would be nice to confirm that though. 

[Andrew]

45 minutes ago, Counter Of Beans said:

I mentioned the yellow grommet issue to the BMW specialist who serviced my F10 (2015 535d) recently.  He'd never heard of it, and looked at me as if I was a bit potty. 

When I asked my local dealers parts department, the helpful lad there, just smiled a wry smile and said that they sell a few.

46 minutes ago, Counter Of Beans said:

 This makes me wonder how common an issue it is,

Very common, they all will suffer from a build up of muck, but not all will leak into the cabin. I replaced mine just to make sure it didn't leak as you can see clear tideline on mine where the water level has been during a heavy bout of rain.

48 minutes ago, Counter Of Beans said:

Any tips for getting access to that bolt near the red wire?

This one?

By feel, and by sticking your phone down the gap and taking a picture.  I use a 1/4" ratchet, 1/4" hex bit holder and T30 bit.

When putting it back together, I found that I needed to line the holes up with a small screwdriver first before getting the fourth bolt in.

I have my cover off 5 times now, done my dads F10 (N57) and helped @VPCAPTAIN with his (B47) and there is certainly a knack for getting it back in place, as you are likely to disturb the heater hose grommet in which it sits.  If its not sitting right along its top edge the bolt holes won't line up.

[Cadwell Parker]

1 hour ago, Counter Of Beans said:

Would it make sense to drill a hole in the plenum cover so that water could drain out that way? 

This is what I did to mine...

 

 

I cut a slot in the rubber seal at the bottom to allow the water to drain freely away. A hole or two might work just as well, as long as the water has somewhere to go if the drain gets blocked.

That hidden bolt is tricky and even worse to get back in. Mine is still out.

[Counter Of Beans]

Thanks Andrew - clever idea to use the mobile to obtain a picture of the fourth bolt position.  So clever, in fact, that I did just that and with a bit of fumbling and my trusty DeWalt work light I managed to get the bolt out OK.  There was a little bit of muck - looked like bits of decaying leaf to me - sat under the yellow grommet - which I removed.  No tide line, which is reassuring.  I also checked the square drain hole in the inner wing and that seems clear.  With a long brush and a couple of rags I was able to clean it all up; job done!  Thanks again - really helpful photos.

Also thanks to Cadwell Parker; next time I might get the drill out or cut a slot as you suggest.  Agreed that getting the holes lined up to reinstall the cover is tricky; I just pushed and pulled the cover until it fitted ; there is a sort of locating dowel moulded into the cover that helps in this task.

I presume that the cover's purpose is just soundproofing?  It doesn't seem to do anything else.  I wonder what would happen if one just didn't bother refitting it?

Finally, I'm surprised my indy - Iridium Engineering in Southampton - hadn't heard of this problem; doesn't exactly fill me with confidence in them, although I had read good things about them.  Anyway, much more satisfying to DIY, I suppose! 

[Cadwell Parker]

57 minutes ago, Counter Of Beans said:

I presume that the cover's purpose is just soundproofing?

BMW call it an ''Acoustic Cover".

[Andrew]

1 hour ago, Counter Of Beans said:

 

I presume that the cover's purpose is just soundproofing?  It doesn't seem to do anything else.  I wonder what would happen if one just didn't bother refitting it?

 

It’s fire proofing cover too, I believe. Fire would go straight thru the yellow grommet if the cover wasn’t there.

[sat]

Hi guys, i'm struggling to get the yellow grommet off itself, any tips on how to get it off? I've tried getting my fingers underneath but no luck?!

[Matthew]

1 hour ago, sat said:

Hi guys, i'm struggling to get the yellow grommet off itself, any tips on how to get it off? I've tried getting my fingers underneath but no luck?!

Push it out from the inside behind the carpet. 

[Bez]

Any help please guys, 

recently i have found water 3 or 4 times now in the rear service panel. Do you think this is related to the yellow grommet problem? 

the car has been stood for a day or so in the rain each time.

i think water does come out of the rear wheel arch. 

you can see the water collected in the bottom of the picture. (Its on a hill) That seems alot. 
 

I cannot find any wet spots higher then the floor pan,  where the water could be coming downwards? Is the any drainage point that can block in the rear hatchback?

 

thanks

 

Edited October 12, 2022 by Bez

[Cadwell Parker]

1 hour ago, Bez said:

Do you think this is related to the yellow grommet problem?

No, I don't think water can get so far back. It works its way back, collects in the left rear footwell then has nowhere else it can go.

Actually you've reminded me of something I've had similar to what you're describing but on the opposite side of my car.

If you look closely you can see a little water in the bottom of the plastic tray behind the right rear wheel arch.

It seems to travel down one of these bunches of wire and soaks in to the fabric edge protector where the wires appear under the fuse box before dripping into the tray.

I've tried tracking it down by pouring coloured water over the tailgate and window seal but haven't managed to replicate it. It only seems to happen randomly. The car got washed yesterday and has been heavily rained on during the last week but checking the tray this evening it's dry. It's a mystery. I'd love to find out what's causing it. A mechanic suggested condensation...?

[Matthew]

2 hours ago, Bez said:

Any help please guys, 

recently i have found water 3 or 4 times now in the rear service panel. Do you think this is related to the yellow grommet problem? 

the car has been stood for a day or so in the rain each time.

i think water does come out of the rear wheel arch. 

you can see the water collected in the bottom of the picture. (Its on a hill) That seems alot. 
 

I cannot find any wet spots higher then the floor pan,  where the water could be coming downwards? Is the any drainage point that can block in the rear hatchback?

 

thanks

 

 

Definitely unrelated to the yellow grommet. 

[Lee535d]

Thanks for the write up on the scuttles. I broke my expanding pins trying to pull them off. I’ve replaced the gromit and the door seal but still getting water in the driver side from the bonnet latch. So need to clear both scuttles, not just the passenger side. Thanks for showing how. I’ve been looking for this

[e39er]

Thanks for the comprehensive write-up - super-helpful. 

My F10 M5 develops a soggy nearside rear footwell after heavy rain. Wet-vac out a litre or two every other day at the mo, given miserable weather. Pretty sure it's the yellow grommet of doom....☹️ Only blessing so far is electrics seem fine.

Immediate problem is, can't find a blog on this topic specific to the M5. The S63 takes up pretty much every inch of space in the engine bay. To my amateur eye, there's little hope of locating the plenum cover without some big boy disassembly...

Anyone attempted this on an M5? Is it accessible from inside the cabin, if the carpets were pulled up? 

Any advice gratefully received..

[Matthew]

11 hours ago, e39er said:

Thanks for the comprehensive write-up - super-helpful. 

My F10 M5 develops a soggy nearside rear footwell after heavy rain. Wet-vac out a litre or two every other day at the mo, given miserable weather. Pretty sure it's the yellow grommet of doom....☹️ Only blessing so far is electrics seem fine.

Immediate problem is, can't find a blog on this topic specific to the M5. The S63 takes up pretty much every inch of space in the engine bay. To my amateur eye, there's little hope of locating the plenum cover without some big boy disassembly...

Anyone attempted this on an M5? Is it accessible from inside the cabin, if the carpets were pulled up? 

Any advice gratefully received..

I think there was some discussion about tis on the M5 on the previous version of the forum and I think it was repaired by going in underneath the engine and removing the under panels to access the insulation cover.

Note that this can't be fixed from inside the cabin as the acoustic panel needs to be removed to clear the debris and the water evacuation routes.

[Andrew]

Anything with a V8 will require you doing the grommet from the underside, remove front under belly and reach up. 

[e39er]

Many thanks both - def a job for the garage in that case. Will let you know how I get on...

[e39er]

On 11/01/2023 at 21:28, e39er said:

Many thanks both - def a job for the garage in that case. Will let you know how I get on...

As suspected....scuttle drains blocked and yellow grommet perishing on bottom edge. Both now sorted by my local indy - thanks again for the write up. 

[0011718]

I had a look under the bonnet of my 2014 F11 today and noticed a large build up of leaves / debris under the windscreen. could get my hand in to clear out so used and extended vacuum tool to vacuum out. Pasenger side was very dry but the driver side had a lot of damp silt so couldn't get it all out. Will have another go at some point when it has dried out. Photo below shows passenger side where the build up was.

Will this help prevent the debris water build up around the yellow grommet? 

[0011718]

Also came across this video on youtube which may support others too in addition to Andrews post.

 

Edited March 9, 2023 by 0011718

[Matthew]

17 hours ago, 0011718 said:

Will this help prevent the debris water build up around the yellow grommet? 

 

 

No, the debris that collects within the plenum around the yellow grommet comes down from the grills at the rear of the bonnet, beneath the windscreen.

[F10-65]

Just finished.  Cleared mine out this afternoon.

Although the tide line is high on the grommet face I haven't had any issues with water leaking in to the cabin but thought I'd have a nose and you can clearly see the tide line on both the grommet and the back of the cover.

I've made the small gap in the seal to let the water drain out but I didn't have the tool/brush to poke down through the drain hole to clear it through.  Now I know how easy the job is though I'll have another go better prepared.

How long does the brush/pipe cleaner need to be?  Any links appreciated.

When mines into my indy for its 10k oil I might ask if they can replace the grommet of doom at the same time.

I couldn't get the final screw back in though, no matter how hard I tried, the one out of sight.

So this is what I found...

 

After a brush round...

 

Heres the tide line on the back of the cover.  It looks like the water may have been escaping here when it reached so high.

 

Then after the mod...

 

Putting the cover back was a pain and the soft cover had been stuck on previously but I found a spare screw to stick through the hole in the middle (no photo of screw)

  

 

[Steve84N]

I need to have a look at mine, the last owner parked under a tree... 

[F10-65]

I park mine under a tree/bush too so was worth a nose.  Took the hoover and went bonkers after removing the two scuttle covers.  They were full of dead leaves