A solution to that major leak you see under your rear floor mats
11-30-2012, 01:01 PM
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A solution to that major leak you see under your rear floor mats My first ever write-up, sorry if it sucks. And yeah I know my car is dirty... it's usually that bad on Friday, the day before I wash it.
Like you, I had a major puddle of water underneath my rear mats. After searching on here, I didn't find anything that would help solv my problem. I did my own troubleshooting and figured out the issue.
Problem: Car has substantial amount of water under rear mats
Contributing factors: I park my car nose down on a driveway that has about a 15-25% grade.
Approach: I took out all parts that would allow me to see behind and under the back seats. In order to lift up the carpet, the seatbelts also have to be removed. I completely unbolted the back pad for the back seat, but just slid it into the "trunk" as to not have to deal with the removal male end of the seatbelt. Upon removing these parts, I found that it was soaking wet underneath the pad you sit on for the back seats. This led me to believe that the leak was coming from the rear somewhere and at a point higher than the pan where the rear seats lie.
Results: Refer to the pictures. With the rear lid open, and car parked on the decline nose down, I filled the outer drainage "rim" of the car with water. It quickly accumulated in the areas in the picture which are hi-lighted. As I kept filling with my pitcher of water, I would then go inside my car to see if any leaks showed up, and they did. The water was bypassing the rubber seal, and trickling down the rear of the back seats. Having my car parked nose down is what caused it to make it past the bottom pan for the rear seat and onto the floor of the car (underneath the rear mats). Had it continued to rain for days, eventually the water would have made it all the way to the front of the car.
Fix: Stop parking my car nose down on a decline. I think GM did a poor job at not properly accounting for a way to drain the water when you are parked this way. Making the seal system better may have also prevented the water from bypassing it. I think applying a small bead of silicone at the seam where the seal and structure meet will help water bypassing in extreme cases of heavy rain, but as of this posting, I haven't done that yet. Since I have discovered this, I have been parking my car nose up on my driveway and haven't had an issue with leaking yet.
I hope this is clear and helps someone figure out the leaking issue they are having. Ask away if you have any questions, and PM'ing me is always an option.
Like you, I had a major puddle of water underneath my rear mats. After searching on here, I didn't find anything that would help solv my problem. I did my own troubleshooting and figured out the issue.
Problem: Car has substantial amount of water under rear mats
Contributing factors: I park my car nose down on a driveway that has about a 15-25% grade.
Approach: I took out all parts that would allow me to see behind and under the back seats. In order to lift up the carpet, the seatbelts also have to be removed. I completely unbolted the back pad for the back seat, but just slid it into the "trunk" as to not have to deal with the removal male end of the seatbelt. Upon removing these parts, I found that it was soaking wet underneath the pad you sit on for the back seats. This led me to believe that the leak was coming from the rear somewhere and at a point higher than the pan where the rear seats lie.
Results: Refer to the pictures. With the rear lid open, and car parked on the decline nose down, I filled the outer drainage "rim" of the car with water. It quickly accumulated in the areas in the picture which are hi-lighted. As I kept filling with my pitcher of water, I would then go inside my car to see if any leaks showed up, and they did. The water was bypassing the rubber seal, and trickling down the rear of the back seats. Having my car parked nose down is what caused it to make it past the bottom pan for the rear seat and onto the floor of the car (underneath the rear mats). Had it continued to rain for days, eventually the water would have made it all the way to the front of the car.
Fix: Stop parking my car nose down on a decline. I think GM did a poor job at not properly accounting for a way to drain the water when you are parked this way. Making the seal system better may have also prevented the water from bypassing it. I think applying a small bead of silicone at the seam where the seal and structure meet will help water bypassing in extreme cases of heavy rain, but as of this posting, I haven't done that yet. Since I have discovered this, I have been parking my car nose up on my driveway and haven't had an issue with leaking yet.
I hope this is clear and helps someone figure out the leaking issue they are having. Ask away if you have any questions, and PM'ing me is always an option.
Last edited by DriveitlikeIstoleit; 12-03-2012 at 08:49 PM.
