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water ingress behind passenger seat - where to locate and clean drains? / 991S coupe 2016

Rosier

PCGB Member
Member
After the relentless rain of the past weeks I discovered that the area behind the passenger seat is wet. There is a (standard) hole in the floor under the seat and when I stick my finger in I can feel maybe quarter of an inch (?) of standing water.
Started to check as I got all kind of strange messages on the dash in very short order. heated steering wheel (don't have) not working, power steering issue, auto start stop not working pcm going off etc.
The water colour is transparent which makes me believe it must be rain water?
The door and window rubbers seem okay so what caused this to come in? Blocked drains? Have been trying to locate schemes or videos but impossible to find. Any guidance really appreciated
 
Check the bottom of the passenger door to see if that is wet, if so the membrane in the door has perforated and is allowing water into the car.
 
Thanks Terry
unfortunately the underside of the door is dry and so is the carpet against the side under the door before it reaches the floor, so I don't think it's coming from there
At the moment I am thinking it's one of the following;
  • broken/damaged rubber in door or side windows
  • AC condense water emptying in the rear seat passenger footwell instead of outside and under the car
  • blocked drains (and can't find any video or scheme showing where they are situated)
And I do believe it's from recent weeks with all the rain as before I noticed noting and regularly clean (no hose...) and hoover the car.
Anyway, thanks again
 
Are you able to remove or lift the carpet in the rear quarter and use a hose over the rear windows to see if you can narrow it down? I’ve read about the a/c drain being caused by faulty hose clips but I would have thought you’d see that as water in the front of the car.

Hope this helps,

Steve
 
Hi Steve,

I managed to slide my hand under the carpet in the small footwell compartment under the left seat and dry it out. It's damp now but not wet anymore. And its only this part which was wet (and the carpet above in the rear passenger area).
I tried to find a scheme of the air con piping - to no avail, although I read in another thread that it caused leakage in the drivers footwell area?
At the moment I don't have enough courage to hose the windows down until it's with my independent with the carpets and seat out.. Obviously I need to find the cause.
Equally I found out that the 991 does not have drainage holes anymore unlike previous models. Apparently the water is supposed to run off the rear window and front. I still believe there could be blockage somewhere as I am in a woody area with loads of needles, they gather on the rear window and in front of the windscreen corners.
Really hoping it hasn't damaged the electrics under the seat..
Anyway, thanks again
 
thanks so much
Going to my independent later today
just poked around a bit bit not loads coming out although t the rear under a hard plastic cover (?) it seems wet..
 
Did you manage to resolve your leak this at the specialist? I’m wondering in case I have to do the same…

Steve
 
Hi Steve,

Car is there at the moment. Will let you know final outcome but here is the feedback they gave me yesterday.
Many (!) 991's are having similar issues (they 'only' did 6 in recent weeks), mine is a (2016 S coupe, but there are also issues with cabs); partly due to aluminium chassis versus previous steel chassis. These have to be bonded instead of welded and apparently the question is whether Porsche are using enough glue..
Majority of leaks start on lh side of the car and are usually caused by a faulty door seal. Couple of hundred pounds for the seal alone and a sh... job to replace according to them.
Process; take out seat and carpets (to dry), check control box(more info down), then hose car down until water starts to appear, usually door seal.
Fix it. Dehumidify the car for a couple days and re install.

I am hoping that by drying the majority out myself the electronics are not damaged. So far they have seen 1 car where it needed replacement, but 'that car was flooded'. If so, the only way to go is Porsche as they need to recode the new electronics box to the car (theft safety I guess and they require both keys). Still the independent would do the 'donkey work' given high hourly labour rates at Porsche themselves.

There are 2 control boxes; the one affected in my case (passenger rear footwell) controls the back side of the car; whereas apparently there is another one in the front footwell..That footwell was dry as both are separated with a cross member that held out the water from moving to the front footwell.

Equally, I thought the water ingress was due to the recent bad weather but the actual issue is that it's a process of months as water slowly builds up until the tell tale signs; wet/ soaked carpets, dodgy electronics. It can easily be multiple litres of water and once electronics are submerged it's going to be very expensive. I am crossing my fingers at the moment. Yesterday all electronics were working but who knows. Funnily (..) enough, I had them quickly check over the car about 3 months ago as last summer it was misting up from time to time. With a quick check we could not see anything (and certainly not if it builds up from the bottom instead of pouring down visibly on the inside..) so I thought nothing of it.

Finally, one would expect Porsche to do a recall or at least acknowledge the issue; probably too expensive or they feel the number of issues versus the total of cars produced doesn't justify. Anyway..



 
[:)] okay, car is back.
Lefthand seat and carpets out to let them dry. Dehumidified car for 2 days till bone dry.
Removed and checked lefthand door rubber = okay. (this also can be poor quality / mine was good) Put additional sealant (not enough or poor quality was the culprit) and refit and check all including all electronics.
Water test for several hours. Check electrics box (all okay!!) refit and hey presto.
£450 in total. Porsche GB would have been considerably more expensive for the same job.
Another 3 cars with the same issue with them as we speak. 991, 981 boxster -4 plate and a 997.

From now I will regularly check under the seats. There are small holes through which you can reach the underlying floor. Stick a finger in and check for moisture before it reaches the carpets 2-3 inches above..
 

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