Tier1Terrier

I expect this post to be met with some skepticism so before I continue, I want to emphasize that what I’m about to share I learned directly from the mouth of the Service Department Manager at my local Porsche dealership. Since this issue has been such a mystery for as long as I’ve been aware of it, I have no reason to doubt what I was told. I welcome anyone who has any information to disprove this to please provide whatever proof/evidence you have.

For nearly a year, I have been scouring the net for the answer to this very question... How to check/clear the water drainage as part of the maintenance of the vehicle. It has been assumed that there is an array of tubes/hoses/lines that carry water away from the roof and around the windshield down beneath the vehicle to drain water. There have been numerous publicized accounts of water ingress that have been blamed on blocked drainage of these illusive hoses. Mostly, the ingress has been found to occur in the rear of the vehicle where one of the first signs is water on the floor of the back seat area. This has invariably wreaked havoc on the vehicle's computers and electrical systems and in some cases causing many thousands of dollars in damage. Or so it seemed. One of the most infamous accounts of this was that of Nick Murray which as we understand resulted in Porsche buying back his vehicle. Throughout all this time over the last year, I have yet to actually find any photos or videos of this maintenance task being performed (clearing of water drains). I've read numerous suggestions and seen diagrams and illustrations on the supposed lines but nothing that concretely showed where these lines begin or end nor any written instruction from any Porsche source explaining how to clear these lines. What I thought was the best explanation involved pushing some high test fishing line down a channel that cannot actually be seen toward the back of the sunroof assembly.

So, Today I brought my 991.2 C2S in to the dealership to get my sparkplugs changed. Since I still have no idea how to clear the firewall drainage lines that is specifically outlined on the maintenance checklist ("Check firewall body drains for debris"), I decided that I would have them do it for me. I was prepared to pay for this mystery maintenance task. I asked my service advisor how much that would be and he said he believed it was about a half hour’s of time but that he would ask the Service Manager first. So we walked over and found the SM and when the SA asked how much time would be required to clear the drainage lines, he said “none”. He went onto explain to both of us that in the 991 coupes, there are NO firewall body hoses or tubes or drain lines or anything like that neither in the front or rear compartment of the vehicle which carry water away from the vehicle. He visually pointed out to me where the water simply flows down the exterior channels (down the sides of the windshield cowl through the same compartment where the gas tank and battery reside, and down along sides of the rear window and back down through the engine compartment) and directly down to the ground. No hoses, not tubes, nothing. Not even with sunroof equipped vehicles. He did explain that this is not the case with convertibles as there are indeed water drainage lines on those models. I looked at him like he was crazy. I know I must have looked shocked and surprised, but at the same time I was feeling a bit relieved and excited. I told him "It can't be. Are you sure?!?!".. that there HAS to be drainage lines/tubes/hoses/whatever and he simply said there is not.

So there you have it, folks. For those of you who have been wondering about this mystery maintenance task, here is your answer. I hope this saves others like me from spending countless hours trying to figure this out.

polobai

Thanks for finding this info out for us-makes sense!!!

ICU991812

So is this for a coupe with NO sunroof? I find it hard to believe that the drain by the battery in the frunk would not be there for all models. There must be some drain from just the front of the vehicle that might collect, and this SA is saying no?

Tier1Terrier

I too found it hard to believe myself as I sat there with the service manager looking at my sunroof to which he Emphatically insisted that there were no drains even from the sunroof roof area. When the sunroof is closed there are no channels for water to accumulate in. Even in the sections on the sides immediately in front of or behind the sunroof. Those rubber strips just cover the part leading to the rear windshield.

Rich_Jenkins

@Tier1Terrier is this phrase "Check firewall body drains for debris" printed in the service booklet that came with your car? I can't seem to find it in any of the pages of services specified in mine. I have a 2017 C2, with service manual document no. WKD902012317. This phrase does not appear on pages 4-8, the tabular list of services for Oil Service, 20K services, etc. If it does, can you post a picture of it?

I don't doubt what you are saying; it's just I can't find mention made of checking the water drains. Maybe it's model specific?

I've had a good look through the service manual pdf for the 991.1 that's floating around here, and also can't find anything (other than the sunroof, and Targa) that mentions water drains, so I'm curious where this comes from.

Thanks!

Tier1Terrier

You raise a good point, @Rich_Jenkins The words I quoted came from the document I'm attaching here which appears to have been published by PCNA, not the official maintenance handbook of the vehicle. Nonetheless, you'll see the "Check firewall body for drain for debris" written under both the Front Luggage Compartment section and the Engine Compartment section on page 1. Outside of this distinction, the questions about how water drains in these vehicles appears to have been looming for a number of years already. Particularly since, apparently, there was a clearly defined procedure for doing so in the 997 series. But also, because of the numerous publicized accounts of people who've experienced failure of systems in their vehicles which was attributed to these drainage lines being blocked. (search "drain" "water ingress" and possibly a few other terms will turn up a handful of topics) It's worthwhile to point out that I am not aware of any known documentation of these issues other than the accounts which I've read about on various forums including this one and maybe another one or two groups (I even recall reading about this in one of the UK specific groups).

So, Is this really a legitimate maintenance issue or a misleading or misperceived idea? Here is an image that someone with a 991.2 posted TODAY on a Facebook thread I created about this. This is what his local Porsche dealership charged him for this maintenance procedure. Did he get ripped off? Maybe so. Did they basically charge him for a service they've done on previous series of 911s (997 for example) and hope it wouldn't be questioned? Perhaps.



In any event, the point of this post was to highlight to people like me who've believed that there's this illusive maintenance procedure that is required to be done on the 991 that this in fact is not required and that there's no secret mystery procedure that Porsche is hiding. I think if anything, what's being hidden from some people is that this procedure is actually not even required. Perhaps what's seen in that document that's floating around published by PCNA has content that was merely cut and pasted indiscriminately from the 997 checklist. Who knows. The bottom line is that there is no procedure that exists for this. There is no DIY. And that this isn't something for people to worry about (that is, people with 991 coupes, with or without sunroofs).

bkrantz

I wonder if "Check firewall body drains for debris" could refer to whatever incidental pathways water might follow, and the chance that a clump of debris could impede the drainage. So "drains" are not tubes?

Schorsch

Posted this in the facebook thread but thought would help to post it here again:Thank you for sharing this very informing info! What I do wonder is, why Nick Murray had all those issues then and others do have water in the passenger compartment as well!?

An assumption from me is that the window seals are not tight and let water through at some point. I did check the sealant of the back window (no whiper) and found out that the black sealant is very soft and feels like "goo". I have read that Porsche changed their sealant due to environmental regulations to non solvent sealant (sic!) and that that sealant resolves itself after some years. Very bad. Only solution is to change the whole back window.

Still wonder if that is the cause of the leak!?

Unsure how to check as well!?

Thoughts on that? Thank you!

Tier1Terrier

The sealant around the window, I would think if it’s in some way compromised, could certainly be an entry point for water. Same for the door and window seals and mouldings. Heck for that matter anything/anywhere that seals the inside cabin from the outside could potentially be a point of water ingress if compromised.

john45in

Guess I'm going to stop worrying about why I haven't been able to find those sunroof drains!

HkPlinker

I clean my CAB drain holes with a wire hanger

RPA911

Thanks for this. I have been unable to find anything either and your explanation makes sense to me.

o4co

Resurrecting this in case anyone else has any new information

Listed on the 2 yr / 20,000 mile Maintenance Menu for '21 C2S (with no sunroof) printout from the dealer :
- "Check front firewall body drains for debris"
- "Check rear firewall body drains for debris"

Looked at several videos about other non-911 vehicles and I think also a 997. In any event I scoured the front firewall and popped the rear lid and the rear spoiler. Nope couldn't find any of the traditional rubber body drain inserts or tubes

I poured water at the base of the windshield on the left, the right and the middle. It drained through the vehicle and onto the floor in a dispersed pattern. I poured some water around the farthest rearward part once you pop the rear deck, the water exited and ran over the rear parking/brake lights and onto the floor. Popped the rear spoiler and the water also ran to the floor. I dont have a sunroof, so nothing to check there

So I could not find any body drains that had tubes or had the rubber grommet type opening in them. Looked all around the underside of the car and also did not find anything

HOWEVER, I did find and kind of already knew about the drain hole and tube that is located in the gas cap area. Carefully poured some water through that small hole and it drained right behind the front right wheel. You can see the small drain tube protruding out below the underside panel. Even though it drained fine, I still ran some weed whacker line through the tube all the way until it stuck out underneath. No debris came out as I would expect

So yeah, it is in the recommended service for this vehicle, and I am sure they would charge for it - but if anyone knows where exactly they are (if they exist) on the 992, that would be great as I couldnt find any