Wet floor pan, both sides.

[tigersdl65]

Nah nothing on the headliner.

[KyleZ71]

My dad had a 96 Tahoe (same body style) and we had that problem in the back. If I remember right the floor pans were not seal correctly from the factory. We took it back to the chevy dealership. They had to remove the seats and carpet, and had to reseal the entire floor boards. After that we didn't have a single problem. Hope this helps

[seph]

I have a '96 crew cab dually that I bought in 2002. Had the same problem pop up in '03 or 04 and got progressively worse over time. At one point we drove through an all day rain storm and it was actually dripping out by the grab handle attached to the A pillar. I replaced door seals, cab lights, windshield, just about everything I could think of, but nothing rectified it. It had gotten to where I couldn't have it out of the garage if it was going to rain. 3 years ago I rigged up a hose with a valve on the very end and started running water all over the cowl while I laid inside and looked for the water. It started coming in worst when I was running it right in the corner (on each side) of the cowl. I pulled the front clip off and it turned out the seam sealer where the cowl and firewall come together had failed on both sides in multiple places. I ground out all the old, resealed with new 3M seam sealer and painted the cowl. Put it all back together and am at 3 years with no more leaks to date.

If you've checked everywhere else, try running water down around the sides of the cowl and see if that shows up...if it does, just start pulling fenders and hood I'd say.

[The Heater]

Hi, Mr. Tiger:

There are so many possibilities for your problem. My best answer is to tell you my story. I was working on my passenger door panel, and found the carpet near that door entry completely soaked. Pulled up some carpet at the wall all the way back, found the carpet soaked to various degrees, all the way back. Pulled the seat on that side and pulled more carpet only to find the water even under the carpet at the tunnel. Checked other side carpet, only found water behind the driver seat.

Consulted some auto body guys I know. They have to deal with leaks a lot. Their collective wisdom told me that leaks are extremely time consuming issues to solve, requiring much dismantling and testing to find the leak, and even then sometimes what you think is the problem isn't (only discovered after you put everything back together).

So, I removed the entire interior. Seats, front and rear, console, interior panels, door panels and carpet/pad. Put the driver seat back in and the driver seat belt (they must be removed to take out the interior panels). Drove around like that for about 7 months, through a cold winter. Did some paint work on the floor above the catalytic converter (repainted it, used a space heater and infra red lights to dry it since it was in the 20's and 30's outside and the truck stays outside).

I checked my heater entry points for water. No leaks. Checked door seals. No leaks ( I actually first thought that was the problem ). Windows did not appear to be leaking. Eventually, after much trial and error, and several months of looking for the water, I found that the body shop that restored my body failed to properly secure the moisture barrier on the passenger door. Come to find out that all vehicles leak water through the windows on the doors. Yes, all of them even the fancy cars. A very knowledgeable paint and body expert told me that. He told me that the moisture barrier must be replaced as originally installed, and sealed, or the water goes into the cabin instead of out the weep holes at the bottom of all doors. You reseal with the 3M dum dum black sticky stuff used typically for sealing body seams. Problem solved.

Or so I thought. I kept checking to make sure this was it. I am glad I took out the interior wall panels, because checking inside the rear passenger side wall revealed more water. When it got enough in there, it seeped into the main passenger compartment and soaked the floor, starting at the front, not the back. Tricky, this water!

The leak came from two more places. The side vent windows on the rear of the extended cab have rubber gaskets sealing where the screws go through from the outside to the inside hinges and latch. One of them had a bad seal when the new window parts were put in when I re-installed the rear windows after the glass people installed the new frames (they seal them to the truck body). It turns out there was one bad screw, a new one I put in, that did not screw down all the way, so that little spot leaked. To find this leak source, I sprayed the inside of the body sheet metal above where the leak was, all the way up to the top of the window opening, with special leak detection powder (it comes in a spray can and if you can't find it, go buy a can of Desonex athlete's foot spray and that should work because it is a white powder). It took several tries, but I traced it to the window, not the frame or the seal around the window, and finally traced it to one hole in the window where a fastener went through.

The second source was the rear window. That leak was hard to find. But I found it one day when I went out to the truck in the dead of winter and observed a trail of water in the fog on the inside of the window. Took a hose, sprayed water where I saw the water coming from, and sure enough on the inside there was more water at that point going down the window. Traced it to the seal at the top. This was new glass installed by Safe Lite after the truck was repainted (we took the whole truck apart to restore the body). So back to the body shop, and they must remove the glass and put in new glass, again, this time at Safe Lite's expense for the whole thing.

Now the problem is finally solved. To make sure I continued to drive with no interior for I don't know how many months, and then started a long project of installing three layers of soundproofing, then carpet pad and carpet. The truck is dry as a bone and quiet as a library so I can hear my stereo at lower volumes. Nice. As the Chinese said a few hundred years ago: "in every disaster lies an opportunity". I got a super quiet truck from this one.

[jake's silverado]

My leak on my 2000 Impala was the windshield gasket. When I googled this there was a common issue with the cabin air filter but mine was ok. Yes I know I'm talking a 2000 Impala but just to point out that it could be anything. My headliner was dry, stay in the truck and have someone run the hose and leave it in one place for a minute then move it. if you have gone all the way around the windshield and see nothing, cross it off your list. Took me awhile but the fix was free when I went to the glass shop and they pumped some special sealant behind the seal.

Is it the original windshield? sealant may have dried, shrunk and cracked...