Cleaning Rear Sunroof Drains

E28 technical advice asked and given! Troubleshooting, modifications and more.

The Baron
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Cleaning Rear Sunroof Drains

Okay, what's the secret here?

It seems my right rear sunroof drain may be clogged as I have had some water saturate the right rear floorboard on days with a lot of rain. Well, I guess not "may" be clogged....DEFINITELY clogged since the water pouring test saw NO water drain out the rear drain.

I took some weed whacker line and tried to fish it up the "out" end and down the "in" end. Is there a trick to finding the drain spot at the back of the sunroof? I took a flashlight and tried to see back there, but I couldn't see very much at all.

What's the secret here? Best method?

~ Ryan

Shawn D.
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Post by Shawn D. »

The tube is towards the top of the slots. If you angle just right with a flashlight, you just might see it (easier at night).

The Baron
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Post by The Baron »

Shawn D. wrote:The tube is towards the top of the slots. If you angle just right with a flashlight, you just might see it (easier at night).

Top of the slots...meaning I want to try to angle the trimmer line upward as I send it back along the sunroof tracks?

Shawn D.
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Post by Shawn D. »

The Baron wrote:

Shawn D. wrote:The tube is towards the top of the slots. If you angle just right with a flashlight, you just might see it (easier at night).

Top of the slots...meaning I want to try to angle the trimmer line upward as I send it back along the sunroof tracks?

No, meaning you want to look around the top of the topmost slot hidden behind the c-pillar vent. You will be sending the line upward and forward from the vent from the outside of the car, not backwards from the sunroof area itself.

The Baron
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Post by The Baron »

Shawn D. wrote: No, meaning you want to look around the top of the topmost slot hidden behind the c-pillar vent. You will be sending the line upward and forward from the vent from the outside of the car, not backwards from the sunroof area itself.

Okay...I see what you're saying.

I already did this, and just kept feeding, and feeding, and feeding...

It probably took 20 feet of line before I gave up. Where does it lead? Is it possible the clog diverted the line to some area it wasn't supposed to be? I heard the line rustling around under the roof.

Mike W.
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Post by Mike W. »

Cross your fingers, but you might have a real problem. On an E24 I used to have the sunroof leaked. No problem I thought when I bought it, just clean the drains. Turns out the small dished areas that the plastic hose is attached to had rusted off the main sunroof. My eventually fix was to glue in part of an E21 sunroof tray over the area. The already rough headliner took more of a beating. The fix worked, but to do it right, you would be looking at pulling the back window and much of the sunroof.

Like I said, hope it isn't the problem you have. BTW, the car was medium rusty overall, not swiss cheese by any stretch, but from the gulf coast and had seen it's share of salt air.

The Baron
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Post by The Baron »

Mike W. wrote:Cross your fingers, but you might have a real problem. On an E24 I used to have the sunroof leaked. No problem I thought when I bought it, just clean the drains. Turns out the small dished areas that the plastic hose is attached to had rusted off the main sunroof. My eventually fix was to glue in part of an E21 sunroof tray over the area. The already rough headliner took more of a beating. The fix worked, but to do it right, you would be looking at pulling the back window and much of the sunroof.

:bawl:

Boy...I sure hope not. Suggestions on how to troubleshoot this further before I take it to this extreme?

Bimmerguy2002
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Post by Bimmerguy2002 »

jesus christ

Feed it through the C pillar, done.

Image

The Baron
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Post by The Baron »

Bimmerguy2002 wrote:jesus christ

Feed it through the C pillar, done.

Image

The Baron wrote:
I already did this, and just kept feeding, and feeding, and feeding...

It probably took 20 feet of line before I gave up. Where does it lead? Is it possible the clog diverted the line to some area it wasn't supposed to be? I heard the line rustling around under the roof.

If you would bother to read the context of the whole thread before offering your oh-so helpful and polite advice, it might do us all some good.

:roll:

Bimmerguy2002
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Post by Bimmerguy2002 »

The pic shows enough, the only way you can access that area is by feeding line through the drain, even removing the entire headliner and sound deadening you cannot get inside of there, its too deep for a human to get to. You need to be able to pull a huge ass vacuum to truly suck everything out of there since a line will never get 100% of the junk out.

Mike W.
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Post by Mike W. »

What position was the sunroof in when you tried feeding the line in? If it wasn't popped in the back, it could have snaked around in the housing and not done too much, except coil up. I've also heard of coax cable being used, it's got more stiffness and is larger, but isn't likely to punch thru the plastic hose. If you have the back popped up, you can kind of see in there with a flashlight. Very kind of, you can't see much, but you could see if something was coiled up in there.

The Baron
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Post by The Baron »

Mike W. wrote:What position was the sunroof in when you tried feeding the line in? If it wasn't popped in the back, it could have snaked around in the housing and not done too much, except coil up.

Meaning not sliding the sunroof back, but merely having it angled up, then?

If that's what you mean, maybe I need to give that a try. I cannot remember if I tried that method or not.

Mike W.
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Post by Mike W. »

The Baron wrote:

Mike W. wrote:What position was the sunroof in when you tried feeding the line in? If it wasn't popped in the back, it could have snaked around in the housing and not done too much, except coil up.

Meaning not sliding the sunroof back, but merely having it angled up, then?

If that's what you mean, maybe I need to give that a try. I cannot remember if I tried that method or not.

Correct, it's a pain, but the only way you can see anything in there. It's only diagnostic, but it can help you figure out what's going on.

alotawatts
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Post by alotawatts »

This may have already been mentioned but..I would try using wire and twist it as you go like a drain plumbing snake. Go easy because the old drain tubing is brittle...worked for me.

Zaffer
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Post by Zaffer »

I used a metal coat hanger and it worked great fro me! However, make sure there are NO hooks, kinks, etc. that can grab as I made that mistake and almost got the damn thing stuck. I know it doesn't get everything out, but it gets a majority of it out. As long as you don't keep the car under trees/tall shrubbery/hedge, you shouldn't really have a problem again, well, not for a while anyway.

GermanlookT3
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Post by GermanlookT3 »

We used to have problems with Classic Vw Bus's drains getting clogged. .
We used the Air compressor with a Rubber nozzle to slam into the hole for the drain, it would push it all out of the way and work fine again. I havent really looked at the rear drains and to tell you the truth I didnt even know they had rear drains on the E28. I cleaned out the fronts of my 533i but If I did the rear I would buy a large solid tube extension for my Air compressor line and feed it into the rear lines. If you cant find anything like that to use, you can try to use some solid brake line that you can buy at the Autoparts store. Tape it on the end of a Nozzle and go buck wild. Or use a Sprayer Handle from a Weed killer sprayer and try that. We used that in the Shop.
Your most likely gonna have to Take your Headliner out to do it Properly :(

spinedocab
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Post by spinedocab »

Try the weedwacker line again. Cut only as long a piece as you need to get all the way through and out the other end, and then chuck one end into a cordless drill. Snake it in while turning it slowly to medium speed. Don't force it. It will go in smoothly until it hits the obstruction, and then it will slowly work its way through that too.

HTH

The Baron
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Joined: Nov 26, 2007 10:30 PM
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Post by The Baron »

spinedocab wrote:Try the weedwacker line again. Cut only as long a piece as you need to get all the way through and out the other end, and then chuck one end into a cordless drill. Snake it in while turning it slowly to medium speed. Don't force it. It will go in smoothly until it hits the obstruction, and then it will slowly work its way through that too.

HTH

Hmmmm...sounds like that may be a good idea.

I'll give this a try this weekend.

Thanks for all the tips & suggestions, everyone!