My son's 986 had electronics issues and the dealership found the problem was the well under the driver's seat (LHD) being filled with water! They replaced all the electronics and a few weeks later, the carpet behind the driver's seat is wet again so back into the shop it went. The dealership kept the car for over a week and cannot find the leak! The car had been sitting and not driven for a number of days prior to the wet carpet so it's not as though he drove through a deep puddle or anything. It just suddenly was wet despite being closed up properly and locked. It had apparently rained during the night.

If the dealership can't find how the water is getting in, chances are it's gonna happen again and the insurance company is not going to be happy to have to keep replacing his electronics, so if anyone has had a similar experience and found out how the water is getting in, please share your thoughts.

I'm sure it's not a matter of drainage being blocked as I'm sure the Porsche dealership lifted the carpets and checked for drainage issues.

Any advice and help will be most appreciated.

 

I can't believe the dealer service department techs are not aware of the possibility of blocked body water drains.

There are a couple under the front trunk, on either side of the battery box. The plastic panels on either side of the battery box will have to be removed. The battery box cover probably should be removed too to give one a better view.

Treat the drain catch basins and the hole -- with a hose connected to it -- with care. You don't want to damage the drain basin -- I think they are styrofoam (at least in my Boxster) -- and you don't want to knock the hose loose or the water will drain into the car and could find another path into the cabin or elsewhere where it shouldn't be.

There is a drain on either side of the top. To expose these the top has to be put into the service position which raises the clamshell and the drains -- one each -- are located under the area covered by the clamshell arms.

Also, feel along the door bottoms. Water can get into the door and if the door membrane is bad this can let water get into where it shouldn't and with the door closed the water will seep out through the carpet and into the cabin.

If the door bottom is wet, if you hear water sloshing in the door when you shake the door, the door card will have to be removed and the door membrane resealed or replaced if torn/damaged. These are generally pretty long-lived but not always. Both of my Boxster's door membranes developed leaks. One just had to be reglued but the other had a tear in it and had to be replaced.

It is even rarer but the seals at the top of the door can leak.

To state the obvious, you (or the tech) have have to find the source of the water into the cabin.

The cabin floor under the seats is the lowest part of the cabin and under the passenger seat is the security module. This does not want to get wet.

 

Agree with Macster on all counts. I am also extremely surprised that the dealer tech's were not able to find the source of the leak. Thankfully I have never experienced this problem, but from what I have heard over the years, this is the order of most likely sources:
1. Drains clogged around the base of the top - would allow water to seep down the firewall behind the seats and into the floor area where the CLU is located. IMHO this is the most likely source.
2. Drains clogged near front firewall
3. Leaks around door panels/door membrane
4. Leaks around door windows

If the car spends a good bit of time outside under trees, it is very easy for the drains to become clogged. You need to be very careful in cleaning the drains to not damage the drain basin or the drain itself. I believe the recommended approach to clean the drains is to blow compressed air through the drain and then test by pouring a couple of cups of water through each drain.

 

No excuse for the dealership not cleaning all of the drains when the car came in the first time and they corrected the damage. This is a pretty common problem on these cars, happened to my brother-in-law's Boxster too.