Sunroof Drains.... W204 Pan Roof, advice needed please!

[moj91]

I've had a good google and forum search but cant quite find the info I'm looking for.

Commonly of course the sunroof drains get blocked with gunk and water leaks into the cabin (in my case through the join in the headliner/a-pillar over the drivers side, during heavy rain). I've seen plenty of advice/tutorials which suggest blowing compressed air/net curtain rail wire/strimmer line down the drains to push the gunk out, however most, if not all seem to be for non-panoramic sunroof models. The issue i have is that the pan roof front drains have a catch style thing over them, like a sink drain, which hinders more or less anything being pushed down them. I'm getting quite fed up of being dripped on every day during this wonderful summer we are having... so i could do with getting the culprit drain cleared. It does drain, but slowly - the other side seems to drain ok from the tests i've done by pouring water down the channels with the roof open.

I'm going to change the front discs and pads tomorrow, so could, if needs be remove the wheel arch liners to attempt to clean the drains from the bottom up - does anyone know if they are easily accessible with the wheel arch liners removed? or are they buried under the sills, meaning that a 'top down' clean is the only way to do them?

Anyone else successfully cleaned the pan-roof drains?

Thank you!

 

[moj91]

So I tackled this at the weekend - after spending a long time freeing some seized caliper carrier bolts, and found thusly:

I could not, no matter what angle I tried, get a length of strimmer wire down the drains from the top on the pan roof, i guess there is something in there stopping it like a 90 degree or something.

So i tried the bottom up method. I couldn't find where the drains come out for love nor money. I was looking all around the cill area with the inner front wheel arch liner out, assuming the outlet to be low-down. I only found it when some water that i had poured into the sunroof recess managed to seep through and drip down. The drain outlet is much higher up the bulkhead than anticipated, approximately the same height as the wing badges (BlueEfficiency/AMG etc.). I have attached a photo/diagram to show its location. It may be behind, or poking through a black soft foam sound deadening piece. Mine was loose so i pulled it out for clarity and better access.

On the outlet as shown is a small rubber outlet hose, which in my case pulled off the solid pipe hose behind with ease for cleaning (and a resulting soaking of my arm as all of the trapped water flushes through. The design of the 'one way valve' type thing (rubber bit) means that dirt gets trapped in it. I cut off about 5mm from the end with a stanley knife to hopefully stop this happening again.

It can probably be accessed without needing to fully remove the rear wheelarch liner section, just the top nuts, but i took mine off fully. If you dont mind getting wet, id advise filling up the affected drain to its max before overflowing into the cabin prior to pulling off or cleaning out this hose valve, so that the held water pushes through the crud with maximum force once released.

Hope this helps someone!!

 

[Paul Calman]

I have a similar problem with my Pana roof and will be looking into this. Thanks for the info I'll let you know how i get on

 

[M80]

I had similar on my earlier Viano.
As the drain bends and weaves on its way to the wheel arch any wire with a blunt end would snag somewhere en route.

From my electricianing days I have a nylon fish tape, with a small ball on the end. That prevents it biting on the way through.
Back than we used to turn a wire end to create a rounded end when fishing cables, if you do that be sure to tape the turned back wire end or getting it out might be a struggle.

 

[moj91]

Barely 4 months later and it appears to be blocked again.
Nearside is absolutely fine.. ugh. Ill take a look at it again over the next week or so.

 

[moj91]

Checked both drains again this weekend, both are clear and running free & draining fast.

Damp patch above drivers side (right) A pillar airbag cover and at upper right corner of windscreen. Airbag is wet behind, I've pulled trim forward but cant seem to unclip to look up to try and find ingress. Water entry after heavy rain, just been sat in car in dark after rain stopped, with torch as easier to see moisture in the dark with the torch than daylight. Inner sunroof recess seems dry. Running out of ideas now... I'd rather not have to try to remove roof liner.... :| hmm.

 

[moj91]

I have a similar problem with my Pana roof and will be looking into this. Thanks for the info I'll let you know how i get on

Any luck?

 

[M80]

No specific ideas but,
what is the pitch of the car when parked?
Could the ingress be from the rear and running down the roof till it hits the stop at the front,
or from the other side even?

 

[Rabk]

I have a similar problem with my Pana roof and will be looking into this. Thanks for the info I'll let you know how i get on

I have the same problem. Once it stops raining I'll have a go. Thanks for the info