My Eureka moment with water drains in our 996 cabs

For 2 months now I have been breaking out in cold sweats about rain here in S. Florida. Why? Because no matter how much I search I could not understand where the rear drains where on my 1999 C2 cab., and how to clear them. Every time I parked it and went into a store or something I panicked that a down pour would flood my electrics or insulation. So let me share my discovery: First it should be clear how to find the drain outlets in the rear wheel wells. It is well documented in threads. Briefly. Remove tire, remove front well shroud by removing the three plastic screw thingys. And there is your outlet. If your lucky the thin rubber shield will still be there. Pull it off and clear any dirt or debris. Easy part. Now, where is the drain "hole" inlet. I say hole because I will now correct that. It is not a hole. repeat, Not a Hole. This is where I believe most of the confusion is. So where is it, let's call it an inlet. Open your top all the way. Then begin to close it and stop it when the clam shell is open and stop it there. You will now be able to see down into where all the top mechanisms are. About 10 inches from where the glass of the rear window would be if it were open down in the now exposed area is nothing that resembles a hole or rubber grommet or anything close to what looks like something purposed for water to drain down into. You will see however, some black molded plastic, again, that looks nothing like a drain opening. Only what I would call crevices. Believe it or not one is the inlet. They may all be inlets that flow together. But trust me that is where the water flows into. What I did was take a funnel and insert the nozzle down into them and pour a tiny bit of water. Sure enough the water poured out the wheel well outlet. EUREKA. So there you are. I then poured loads of hot water to flush anything out. Again guys, not a hole. And what is the inlet, is nothing that common sense would lead you to think it was. If anyone is still confused I would be glad to take pictures and describe it further. What's even more puzzling, is I have seen where people say to remove the rear speaker and you will see the drains. Well, I did this and nothing even close to what resembles any drains are seen. Except!! There is a corrugated black plastic hose that comes out from what would seem to be the wheel well area. Problem is, at least on mine, it comes out but just stops and the end is just flopping around and not connected to anything. At first I thought, Oh boy, this must connect up to the area where the actual drain inlet is. I thought maybe it had disconnected or broken and fallen down. But after looking at it, it is impossible for it to go up anywhere. I was tempted to shoot water down it, but thought better thinking it might be a factory electrical tube for wiring, so I didn't. I could also take a few photos of this "tube to nowhere" tomorrow and maybe someone knows what it is or what it's for. I believe it has nothing to do with drainage. Some said there is a dip pan or collection area. I saw nothing of the sort. In fact, there is too much wiring in that area, that I can't imagine Porsche putting drainage devices in that area. As far as the front drains, I have located the holes by the battery. As far as I know these are the only drains up there. If I'm wrong please educate me. At this point I'm calling my car sorted as far as the drains go. Now just need to check them yearly. Thoughts, correction, questions, additions welcome.

Thanks.

I guess this helped you? If so, you're welcome.

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Yes it did.

Removing the rear speaker will reveal a "pan" of sorts. It's more of a plastic chute on top of the rear wheel well housing. This is where the water is directed from the clamshell "crevice" drains, and down into the the drain exit at the lower part of the wheel well. Try this: Open the clamshell partway. Remove a rear speaker and sit in the back seat with a flashlight. Have a friend use a funnel to pour a bit of water into the clamshell drain crevices. Watch where the water flows inside the speaker hole. Better yet, take a video and post it here!

Yes, please post pictures if you can. I'm not understanding "About 10 inches from where the glass of the rear window would be if it were open"

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Hey! Leave Him alone! Did you know he is in the phone book too!!

A. Rain water enters the "groove" around the edge of the clamshell lid. B. It flows into drain holes or "slots" at the front edges of the grooves C. An upper drain tube (1) collects the water and dumps it into a plastic water collection tray (2) on each side, located behind the speakers. This is an open tray with a channel to direct the water down to the lower tube. It's like a water slide. (Note: This is a bizarre design.) D. The water collection tray has a hole at the bottom. The lower tube (3) connects here and directs the water to the wheel well, and onto the ground. (Note that if the lower tube clogs, water would back up into the water collection tray, and then overflow behind the interior rear passenger panel, and onto the rear floor.) This system can clog at any point. When cleaning, I recommend blowing out both the upper and lower tube with compressed air or vacuum, which requires removing the rear wheel well liner, as well as the interior rear speaker.

HERE are the locations of the four drain holes in the frunk. There is a Porsche TSB regarding these, You definitely want to execute the TSB or risk flooding the interior cabin and destroying your electronics under the seats - ask me how I know.

I would like to see photos of all drain holes, thanks.

OK. In the photo marked A & B you are looking at the top that was put all the way down then raised so the clam shell is the only thing up. Make sure you stop it in the position where the 2 large retractable wings on either side are still in the vertical position, otherwise your view will be blocked somewhat. The photo is looking down where the canvas top would meet the quarter panel just behind where the rear window meets. The arrow marker A is the actual channel where the water flows into as in drains off the canvas top. Again it is not a round hole, but slot a slot or channel. If you shine a flashlight down you will see what appears to be like a water slide where the water goes down into the drain pan. I will point out the drain pan in the next photo marked C & D. Ignore arrow B for the time being. The photo marked C & D is the rear side speaker removed. D is pointing to the drain pan which has a hole in the bottom which drain out the outlet in the rear wheel well. This hole in the bottom of the pan you want to make sure is clear of any debris. Also check the waterfall from arrow A and make sure nothing is obstructing it and clear of surface dirt or debris. Now...arrow B is pointing to the long rectangular openings that are actually cut in the metal of the quarter panel. There are 3 of them, the one you see, and 2 others as you follow the panel towards the rear of the car. These are simply additional drain slots that do not drain into the drain slots that allow water to go down the waterfall into the drain pan. They simply allow water to drain directly into the wheel well randomly, no tubes or waterfall channels attached. You will want these to be clear of debris. Most of the water from rain will be collected by the A arrow channel since it collects the rain that cascades down the canvas top. The B arrow slots simple catch whatever little direct rain collects in the outer quarter panel groove. Arrow D points to a tube that attaches to a nipple on the inside of the quarter panel and emptying in to the collection pan. Arrow D shows the tube properly seated in the clip which holds it so it flows into the same collection pan that collects the water from the top channel inlet down the waterfall. Make sure it is clipped into the clip. Arrow C shows the tube which has slipped out of the clip and not directing it into the collection pan. This is not good since water will now come out of it and go places you don't want it to. I do not know where the inlet is for the tube, but it is clearly part of the drainage system since it clips into the collection pan. I am going to replace these corrugated plastic tubes with rubber tubes so they won't break. As you can see the tube is barely long enough to fit into the clip. This is because it has broken off and become shorter than it should be. When I do this I am going to do a smoke test on it with a cigarette using a elongated rubber hose to see where the inlet is for this drain tube. Smoke should cone out where the inlet is. This is the basic design of the rear drains. It goes without saying to do both sides. Hope this is clear. Once you get the top positioned correctly with the retracting wing out of the way, it is quite self explanatory.

Sorry, where i say photo C & D, should be D & E and, arrow E points to the drain pan, not arrow D

Thanks for the pics

Here is a better photo using a flash of the speaker removed showing the tube D, collection pan E and an addition arrow F indicating the waterfall (water flows in direction of arrow) channel from the top (arrow A in the other photo) inlet slot. The drain hole leading to the wheel well outlet is right about where the clip is on the bottom of the collection pan. That is the hole that needs to be cleared and is the culprit for water the entering cabin. If it's blocked and the pan over flows it goes right down to the interior carpeting. This hole was block on both sides of my car with rubber chunks and grime. Expensive water damage waiting to happen.

[QUOTE=rolex11;12982598]dporto, adjust you meds. Oooo a little sensitive are we Naven? More pictures please? I still haven't quite gotten it...Oh and btw, I'm pretty sure this stuff is covered in your owners manual

Thanks for the excellent photos. I always have trouble interpreting Porsche's diagrams. The pictures really clear things up.

Thanks Rolex11 for the sweet photos....I will check mine out.

Today I replaced the corrugated black plastic hose with clear soft plastic hose (see pic arrow D). I used a long section and attached it to the male nozzle on the inside quarter panel where it connects and blew cigarette smoke into it. Did not see any smoke come out anywhere. I was expecting to see it come out where ever the water inlet is for the tube, but didn't. I seemed to be able to blow it in quite easily with only a little back pressure. I did it several times but no smoke came out anywhere. Maybe mine are clogged. My guess is hose is fed by the 3 slots (arrow B in earlier photos) in the top outside quarter panel channel. I asked if anyone knew where the water inlets are for these. Does anyone know for sure? I know they are for drainage because the hose clips into the collection pan. Worth while upgrade since the black plastic OEM hoses break and crack and come loose from the inside quarter panel nozzle where they attach.

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I'm bumping this today because I had the same problem and the guidance here was invaluable. I have a 997 but the drainage systems are the same. Were you ever able to figure out where the water inlet is for the black tube? Before buttoning everything back up, I asked my cousin to spray water all along the side panel of the car, the top of the canvas roof, the back side, the side and back clamshell and no one water was coming through the black tube. All of the water was channeled down the "water slide" but could not figure out where the inlet is for that tube! I just want to be sure it is all working correctly now before I leave my car in the rain again. Anyone else?

Does anyone know of a different reason why there would be water on the floor? I discovered a little bit of water in the rear driver side footwell. Last weekend I pulled the carpet up, dried it all out. I was pretty happy with how dry I got everything. I also cleaned out all the drains, and figured all was good. The Porsche sat in the garage all week, I drove my Jeep to work everyday. Today I opened the Porsche up to check on it, as I am going to drive it tomorrow. I discovered more moisture in the rear driver side footwell!! I don't get it. It was dry last week, and sat in the garage. How can it be wet again??

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I'm bumping this thread again - same issue here - wet behind the driver's seat, and some (but not as much) wetness on the passenger side. If I push my finger into the carpet seam under the front of the rear seat there is water there. Same as above, my car was parked in covered parking for a week, then in the garage. It has not been in the rain for a while - but it has been at the carwash. So logically that is where the water is coming from - and it seems like clean water too. Also I have the hardtop on. Any suggestions are greatly appreciated! Daryll

This is a great and helpful thread. I had annoying soaked rear passenger carpet. I found my clog by taking the tire and the three plastic nuts off. Thank god the inside of the car is painted under the carpets. This is a major rust incident waiting to happen. Thank god there were no signs of rust whatsoever. Easy enough to clean. Should be on everyone’s maintenance list.

Thanks for the post rolex11. I, like others on here, couldn't work out the waterflow. I have just had very damp passenger carpets that sent the spoiler and rear lights on my 997 crazy. I've cleaned the wheel arch drain (quite a bit of silt) but still have a suspicion that there is another blockage. Did you find out what drains feed the corrugated tube? I poured water into slot B in your photo and it seemed to come out at the front wheel?? I'm sure when I've done this in the past it came out of the rear wheel arch drain so I'm worried I have an unseen blockage between B and the corrugated pipe connection point. Any ideas?

These photos say exactly whats going on: https://cimg5.ibsrv.net/gimg/rennlis...512a4f29f.jpeg https://cimg1.ibsrv.net/gimg/rennlis...c110dd46e.jpeg https://cimg4.ibsrv.net/gimg/rennlis...cd9590eee.jpeg https://cimg2.ibsrv.net/gimg/rennlis...58988b626.jpeg They were in 'my new ride' thread:

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It is just my guess that the slots feed the corrugated tube. WOW, it came out at the front wheels? That doesn't seem right. Now you have me curious again. I think I'll do some testing tomorrow. Like I said, I once attached a longer tube and blew smoke in it. Never was able to see any smoke coming from anywhere, in fact, if I remember it was sort of hard to blow into the tube, almost as if it was blocked. My only other guess is it may just be a vent to a closed/sealed area where perhaps condensation can accumulate and this is simply a opening to vent it and no water actually exits. Since there would be only small amounts of liquid that would result from condensation, routing it to the collection pan may not have been totally necessary but done for good measure. A test I've been wanting to do is to route the tube into a small bottle with an aspirin at the bottom, and after some time check to see if there's any water in the bottle or if the aspirin is dissolved. In case you didn't figure it out, the aspirin is to detect if water entered the bottle and then evaporated. Of course you could use anything that would show signs of water, a piece of paper, sugar, etc. I would suspect that if after several months of washes and spending time in rain storms, if there is no water detected that this is not a drain but simply a vent.

Rolex11 - I think you have a career in forensics! tom__w - thanks for the photos. Your https://cimg4.ibsrv.net/gimg/rennlis...cd9590eee.jpeg photo gives a clue. Is the metal tube that the corrugated pipe connects to just an open hole on the other side of the panel? If so, the location doesn't seem to make any sense to me?

Must be smoking some good **** to get so deep into this!

Clean out my drains a few months ago - this thread was very helpful. My car had been parked outside for quite a while before I bought it, and there was basically mud in the drain system. Once I got that out, the drains work normally and my carpet is dry. Thanks to @rolex11 for all of the information and research that he did to show us how the system works. Daryll

So does anyone know the purpose of the corrugated pipe? It looks like it's half way up the body so what does it drain?? s My 997 cab is still draining in a way I'm sure it's not mean to. If I pour water into this slot: It drains from just behind the front wheel, where there is a grommet in the bodywork: Any suggestions what to check??

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The top of the pipe is the drain for the pan directly above it. The other end should terminate just behind the rear speakers into a catch tray that drains to a spot in the wheel arch just in front of the rear wheels. That's on a 996. I presume it's the same.

Thanks @tom__w . What I can't understand is if I pour water into the slotted drain, how it is running to the front wheel arch? Shoudl that slot should end up in funneling water to the corrugated pipe? In your original photo does the water flow along the bodywork, either arrow A or arrow B, or is there another plastic guide/pan that funnels the water to the top of the pipe?

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Firstly, these are not my pictures. They were posted in a thread I started asking about drainage. Looks to me like water drains into the top channel where you are pouring water and drops into the square box (above where you have 'A'). From there it runs into the tube and dumps behind your speaker. Remove your speaker and you will see what I mean. If that catch tray is full, water will more than likely overflow and exit like it is on your car. Check the drain that is behind your speaker and runs to the valve at your rear speaker. If clogged, you can clear it with compressed air. But BE CAREFUL. If you blow too hard, you can dislodge tubes in the body.

Ok, sorry, I thought you took the pictures! I have the speaker (and now also the trim) removed from the passenger side. The tube never gets wet. I took the driver side speaker out just now and poured water into the equivalent slot on the drivers side. This dumps water to the front of the rear wheel arch (as expected) but the corrugated tube on that side doesn't get wet either. I think it's take it to a garage time. No idea what else to try. I've seen other posters have a similar issue (discharge to the front wheel) but no conclusions why...

Had the 3 panels off the rear of the frunk area over the battery, and could see 4 drains. One on passenger side was full of leaves but not fully blocked, one on driver's side completely blocked with what looked like dirt. A little time with a wet vac and metal rod got the drains cleared and all detritus out of surrounding area. Probably good for another 10 years. While cleaning cabriolet top noticed water runs into a small gap on either side, and comes out under vehicle in front of rear tire. Both sides draining fine so won't pursue further until opening panels in rear of car.

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Hey mph070770 Did you ever get a resolution to this problem you have? Everything you have explained in your posts matches my problem exactly. These drains, pips, trays etc all seem to be over complicated and its difficult to identify whats what. It all started this weekend with heavy rain here in the UK. When I looked out the window in the morning I noticed the rear end of the car lit up like a Christmas tree and the spoiler doing some crazy moves! All without the key in the ignition! Further inspection found the rear passenger (US Driver side) footwell with a pool of water and the rear control units submerged. I quickly removed the battery and using a sponge, managed to remove most of the water from the swimming pool the rear module was sat in. Subsequently, I removed the front seat so I could access the rear modules to remove them. After some gentle cleaning with water and then some alcohol to clean up, I was lucky to have saved the modules. Thats where the good news ends... With the seat still out of the car and half the rear interior removed, I'm still non the wiser how this amount of water is accessing the car nor how these annoying drains actually connect up. Any assistance, guidance and the all-important pics would be much appreciated!! Many thanks!!

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Look at post #31 to see exactly what is going on. Pictures are also here: These photos say exactly whats going on: https://cimg5.ibsrv.net/gimg/rennlis...512a4f29f.jpeg https://cimg1.ibsrv.net/gimg/rennlis...c110dd46e.jpeg https://cimg4.ibsrv.net/gimg/rennlis...cd9590eee.jpeg https://cimg2.ibsrv.net/gimg/rennlis...58988b626.jpeg

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Thanks tom_w I have studied those pictures to try and understand the flow. For me, nothing really comes out of the corrugated flexi tube. Could it be that its blocked at the top before the flexi tube where there's a right angle? If that's the case, I assume the water will overflow at the bottom of arrow "A" in the pic and find its way into the footwell? How on earth can you get into that point to clear it out?

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Have to use a flexible coat hanger type thing. You could also use compressed air but if you do, be careful not to dislodge the tube. Others have done it, even replacing the tube with clear tubing.

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Sorry for the zombie threat revival. Tom, did you ever figure this out? I have same problem and have confirmed all lines are connected and clear. If I put water directly into the catch tray it flows out where it�s supposed to, the valve in wheel well. I�ve replaced the flexi line and am 100% it is connected and I can blow through it freely. However water poured into drains at roof run out rocker panel in front of the wheel well and tray never sees a drop.

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I've not dealt with this since the thread was posted. I've since sold that cab. I have another TT cab now without any issues.

Thanks Tom

If it is any help:

Thanks Joe. I have that diagram, as well as pics from this thread and others. I guess I should be happy water isn’t getting to interior, but it’s not getting to the drain tray either which is concerning. It just runs out of the fender well above bumper cover and rocker panel in front of rear wheels (not valve in wheel well, as it’s supposed to).