Like others, I have had a continual major water leak into the driver side of my 2001 Bonneville, which resulted to water standing in the rear passenger floorboard on the driver side. Note that I do not have a sunroof. I traced the problem to the driver door, which water passes through to exit to the outside. Inside the door is a big molded plastic cutout. This is sealed with a tar like adhesive. When this adhesive breaks loose, it allows water to enter the cabin.

I took the door apart and reattached the adhesive, but still had the water leak into the cabin. What I did next was take out the interior door cover, and the driver seat. I then sat inside the Bonneville and had a friend run a hose over the Bonneville. I saw the problem. The water was coming in and out of the bottom of the door- the corner nearest the engine, not the top. I spent all my effort sealing the top, and casually sealing the bottom. I sealed the bottom, without sealing the top, ran the hose and no more water leak.

Lesson learned- although it seems wrong, focus on the bottom seal if you have water entering your cabin and do not have a sunroof.

That black tar-like stuff they use to seal the water shields is called butyl. Instead of re-sticking it with the existing stuff, you can buy it in rolls at any auto body supply store. If they don't know what you are talking about, tell them you are looking for the stuff windshields used to be sealed with on older cars. Get the smallest diameter stuff they have. One roll will do a little more than one door.

Roy,

Thanks. You bring up a great point I forgot to cover. I did the latest repair later in the evening. I went to ACE hardware, and the adhesive I bought didn't work, the plastic just slid down the door. I had to remove it again and clean it. Next I tried a 3M product, quick drying, it also did not work, had to remove and reclean. Finally, at Advance Auto parts I found a adhesive that did work, but I could only do a section at a time, and had to hold each section wating for the adhesive to firm up, which made the seal not nearly as good as I would of liked.

Lesson learned- first step of this job should of been aquiring the butyl. Costly miss on my part.

Mike, this comment is for other people reading this post. You need to understand our doors have what is referred to as a wet water management system. Instead of keeping water out, they are designed to take water in and drain it to the rocker panels, just outside the door seals. The reason you need to know this is because you can easily route the adhesive/butyl for the plastic water shield incorrectly along the bottom of the door and block off the drain holes. If you do that your door will fill with water, and the water will end up where you don't want it. The drain holes along the bottom of the door must be covered by the water shield, but the butyl must be routed below the drain holes.

If you are doing this repair and aren't sure what I am talking about, post pictures and we will guide you down the right path.

Hey guys, i have a major water leak im investigating.

Major water in back passanger side floor that appears to move forward towards front passenger half way but not all the way through the whole front carpet.

Not sure could be the other way around also.

Thanks Guys

Please don't reply to posts that are older than 6 months and don't reply to other peoples threads with your own issue.