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Water entering from bottom of trunk, strange screw piercing trunk?

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We recently had flash flooded roads here in the Philly area. I was driving through some serious (inch or two) but not life threatening areas of roads where the water was moving quickly. This resulted in a lot of splashes up against the underside of my car, I'm sure (probably worse than going through a car wash with the "undercarriage" feature). Since then, noticed a musty smell. Thought it was water that had gotten into the cabin AC system. Nope -- eventually realized that the lower "under floor" storage area in the truck must have taken on a lot of water, as a blanket there was soaked, and the carpet / trunk liner was damp. Time to investigate. Many strange surprises ahead.

Removing the carpet / trunk liner revealed a sound insulating mat. It was soaked (this is days later). I could not fully remove that because the amazing design includes a round hole in the corner through which passes a wiring harness.
20180828_122959_sm.jpg


However, I could lift it 99% out of the way to see the trunk bottom.

Does anyone know if there is an easy and safe way to remove this sound insulating mat? Meaning a nearby harness connecter that can be disconnected without danger of shock?

Under the mat, the floor of the trunk had residue of mud confirming my suspicions that this was not collected rainwater; it was ground water that had intruded upwards.
Next up, the surprises I found under the mat:
  • What appears to be a screw piercing upwards through the floor! Definite possibility for water incursion. Anyone ever see anything like this?
20180828_123032.jpg
  • Strange metallic foil "patches" in various places, and one huge one that covers most of the trunk bed. Is this normal?
20180828_123024.jpg
  • The big gasket around the wiring harness is supposed to seal the hole where the harness passes through the trunk floor. However, in my car, the gasket was not properly in place. There is a thin groove in the gasket that the metal of the floor is supposed to mate with to make a tight seal and also prevent the gasket from being pushed upward by water pressure. But the gasket had not been pushed down forcefully enough and the floor metal was not inside the groove.
20180828_122959_lg_cropAnnotated.jpg

No, as for any abnormalities (screw piercing the floor, gasket not installed properly), this may or may not have been this way from the factory. This is a 2014 manufactured P85D and for that model car, it was an option to install a 2nd charger. The car was an Inventory unit, so I did not get to configure it. So I purchased the 2nd charger option and it was installed by the local Tesla service facility when it arrived (none in stock). So in theory, any strange things in the truck might have happened during that service. The screw thing seems really unlikely, though.

Love to hear from anyone who has information about this stuff or similar experiences. I've searched the Internet and these forums and there's surprisingly little information about what's under the insulating mat in a Model S (or how to remove it if that's even possible without cutting through the corner to the hole).

And for those curious and not paying attention to the mud residue, yes, I'm familiar with the panoramic roof leak (mine serviced once but still does it; 2nd service for that scheduled), and with the hatchback leak where it fills with water and pours out when you open it (already serviced and seems fixed).
 
Update: I took the car in to Tesla Service (had other things for them to look at at the same time). The came up with what they believe is a very solid guess as to what happened.

I had a supposedly good body shop (no, not a Tesla certified one, but read on) install the custom Torklift EcoHitch for the Model S. So no real body work -- because the EcoHitch literally just bolts onto the car behind the bumper cover using some of the same bolts that are used for the bumper reinforcement plate that is attached if you get the rear facing child seats. Tesla Service believes that during the installation, the body shop broke a piece under the car (not sure which piece; I will update later), and instead of replacing the broken part, they put things back together by drilling the screw through the part and through the floor of the car. They are probably also responsible for unseating the rubber gasket around the wiring harness and not putting it back properly. The gasket is most likely the primary way the water got into the trunk, as it is a big hole. The screw actually filled the hole it created, so not likely a source of the water.

Tesla Service is (at my cost) replacing the broken part, removing the screw, and filling the hole. I could try to go back to the body shop that likely did the damage, but that was 2.5 years ago when I had the hitch installed. (BTW, I don't tow anything; it's for a bike carrier.)
 
We recently had flash flooded roads here in the Philly area. I was driving through some serious (inch or two) but not life threatening areas of roads where the water was moving quickly. This resulted in a lot of splashes up against the underside of my car, I'm sure (probably worse than going through a car wash with the "undercarriage" feature). Since then, noticed a musty smell. Thought it was water that had gotten into the cabin AC system. Nope -- eventually realized that the lower "under floor" storage area in the truck must have taken on a lot of water, as a blanket there was soaked, and the carpet / trunk liner was damp. Time to investigate. Many strange surprises ahead.

Removing the carpet / trunk liner revealed a sound insulating mat. It was soaked (this is days later). I could not fully remove that because the amazing design includes a round hole in the corner through which passes a wiring harness.
View attachment 329825

However, I could lift it 99% out of the way to see the trunk bottom.

Does anyone know if there is an easy and safe way to remove this sound insulating mat? Meaning a nearby harness connecter that can be disconnected without danger of shock?

Under the mat, the floor of the trunk had residue of mud confirming my suspicions that this was not collected rainwater; it was ground water that had intruded upwards.
Next up, the surprises I found under the mat:
  • What appears to be a screw piercing upwards through the floor! Definite possibility for water incursion. Anyone ever see anything like this?
  • Strange metallic foil "patches" in various places, and one huge one that covers most of the trunk bed. Is this normal?
  • The big gasket around the wiring harness is supposed to seal the hole where the harness passes through the trunk floor. However, in my car, the gasket was not properly in place. There is a thin groove in the gasket that the metal of the floor is supposed to mate with to make a tight seal and also prevent the gasket from being pushed upward by water pressure. But the gasket had not been pushed down forcefully enough and the floor metal was not inside the groove.

No, as for any abnormalities (screw piercing the floor, gasket not installed properly), this may or may not have been this way from the factory. This is a 2014 manufactured P85D and for that model car, it was an option to install a 2nd charger. The car was an Inventory unit, so I did not get to configure it. So I purchased the 2nd charger option and it was installed by the local Tesla service facility when it arrived (none in stock). So in theory, any strange things in the truck might have happened during that service. The screw thing seems really unlikely, though.

Love to hear from anyone who has information about this stuff or similar experiences. I've searched the Internet and these forums and there's surprisingly little information about what's under the insulating mat in a Model S (or how to remove it if that's even possible without cutting through the corner to the hole).

And for those curious and not paying attention to the mud residue, yes, I'm familiar with the panoramic roof leak (mine serviced once but still does it; 2nd service for that scheduled), and with the hatchback leak where it fills with water and pours out when you open it (already serviced and seems fixed).
 
Update: I took the car in to Tesla Service (had other things for them to look at at the same time). The came up with what they believe is a very solid guess as to what happened.

I had a supposedly good body shop (no, not a Tesla certified one, but read on) install the custom Torklift EcoHitch for the Model S. So no real body work -- because the EcoHitch literally just bolts onto the car behind the bumper cover using some of the same bolts that are used for the bumper reinforcement plate that is attached if you get the rear facing child seats. Tesla Service believes that during the installation, the body shop broke a piece under the car (not sure which piece; I will update later), and instead of replacing the broken part, they put things back together by drilling the screw through the part and through the floor of the car. They are probably also responsible for unseating the rubber gasket around the wiring harness and not putting it back properly. The gasket is most likely the primary way the water got into the trunk, as it is a big hole. The screw actually filled the hole it created, so not likely a source of the water.

Tesla Service is (at my cost) replacing the broken part, removing the screw, and filling the hole. I could try to go back to the body shop that likely did the damage, but that was 2.5 years ago when I had the hitch installed. (BTW, I don't tow anything; it's for a bike carrier.)

Have you noticed water in your trunk since?
 
Just to let people know - water can also infiltrate into your battery and cause the car to shutdown. This happened to me this week. Drive through 4-6 inch puddle. Not immediate but next day car would not restart. Towed to dealer - there is water in the battery compartment and also around the main fuse of the car corroding it. It was only exposed for two to three days. Not covered under warranty. Do not drive your car through water - even though Elon tells us the car is like a boat! I do love Elon though!
 
Just to let people know - water can also infiltrate into your battery and cause the car to shutdown. This happened to me this week. Drive through 4-6 inch puddle. Not immediate but next day car would not restart. Towed to dealer - there is water in the battery compartment and also around the main fuse of the car corroding it. It was only exposed for two to three days. Not covered under warranty. Do not drive your car through water - even though Elon tells us the car is like a boat! I do love Elon though!
Elon says a lot of things. "P100D loaner for everyone", "FSD sooner than ANYONE thinks", "P85D is a 700hp car", "SDK coming soon", "AP1 will be able to find you anywhere on private property", "you'll be able to summon your AP2 car across the country", etc, etc.

Never trust what Elon says, only what he already accomplished and you can personally verify. He's so much more impressive when judged on accomplishments alone, and none of his forward looking hot air.