This is for a car that I previously owned, sold it to a friend. 09 G37X, my buddy has found that three days in a row now the rear seat carpets have been soaked. Both of them. He told me he soaked up as much of the water as he could each time, but it keeps coming back. Again, it has not rained, snowed, any of that here. There’s a leaking door seal, he will be replacing that, however again... no rain. He’s told me that it does not smell like anything, so that rules out fuel. (He parks on a pretty steep angle in his driveway, backed in with nose facing down towards the road)

If anyone might know what’s going on, please let me know. I’ve advised him to remove the rear seats, will be telling him to remove the stuff in the trunk (spare tire, jack and stuff)

 

Could it be residual water from previous precipitation events? Being parked on a steep incline allows the water to puddle up/make it more noticeable? Though being he parked "nose down" it would seem the water would migrate forward.

 

exactly what I thought as well. He did say that the front was also wet, but after soaking it up it hasn’t returned. I know I had to rip the carpet up and soak up water from the dreaded FR sunroof drain leak, but I got it bone dry (rags, airflow, vacuum, whatever I could do) Hopefully that you are correct though.

that being said, where could it possibly come from? Can water accumulate in the parcel shelf? I can’t imagine it can make its way from the spare tire hole, the angle isn’t quite that steep. Regardless, I will hope for the residual scenario. That being said, it must be cleaned up tonight as it’s going to be freezing temperatures for the next little bit in Ontario.

 

Rear sunroof drain(s)? The rear drains go down the C pillar and exit near the rear wheel well. This would be about the same level as the trunk floor. Being that your bud parks at a angle (nose down) any water leaking from those grommets will travel "down," under the back seat/bottom cushion, and eventually to the floor.

Conversely, if he parked level, or "nose up," any leaking water would likely seep to the bottom of the trunk/spare tire well.

You can access the drain grommets from inside the trunk by removing the trunk room trim pieces. I found this image from the technical bulletin Infiniti issued for the drain hoses in the Q50. The design/location should be similar, if not the same, for the G37 (same platform):

 

That definitely sounds like it could be a possibility. Will have to let him know. Thanks ILM!

 

The water just sits there in a valley as the floorboard is uneven. The water level may not have been high enough to touch the carpet. When you started to drive the car it could have slushed around and got the carpet wet.

 

yeah the floorboard has a well right in the back right corner, it can sit there. It’s still confusing me though cause that would cause it to go up to the front on that angle. It seems to only get when when it’s parked

 

No, the front floor board in the G37 is not flat once you pull the carpet up. There is Styrofoam filling in the valley and that is where the water collects.

 

Precisely what I said
I didn’t add that there was another bit towards the trans tunnel that I noticed though. I haven’t heard any complaints for a few days so I hope it’s fixed? Never got any verification that he pulled anything though...