Next to the intake/gaskets problem, this is the main reason (non-club type) people want to sell their Bonnevilles for 50 cents on the dollar.They love the car, but water leaks drive them nuts. Some people have let it go to the point their car smells swampy or mildewy, most of the time.
I have a '95 SE, '96 SSE, and '98 SSEi. All three have had moderate to "severe" leak problems. Bought the 95 off of a 2 year lease, so the problems developed over time. The other two were bought from owners who were at wits' end with the wet. It took about an hour and 2 tubes of clear VTR to solve these "major" problems. Of course, after i has bought the cars.
Two steps will cure 80+% of water problems. 10% will take some thought and investigation. 10% are real pains.
Here'* the two things to check for.
-If it'* a 95, your rubber door gaskets have dried out, shrunk, and pulled away from the body. Usually, in the corners.
Check all four doors, and run your hand against it to see if, and where, it has pulled away. Should some be found, replacing the gasket would make sense. On the other hand, it'* never too soon to learn one of the many wonders of a $5 tube of VTR. Use the VTR to re-secure and fill in gaps left by the aged rubber.
Next, look along the areas where the gunnels or gutters (whatever you want to call them) run along the edge of the roof above the doors. The metal has to be air tight to the body. Bets are it isn't and it can cause problems at all 3 pillars. Fill those gaps the entire length, from front to back,with the clear VTR. If you take your time, it will be unnoticeable to all but those who stick their nose right in it and are specifically looking for it. You can't miss the slightest area, because the gutters combine with the gaps to make an incredibly efficient waterleak system.
BTW, if you have a lot of carpet getting wet now, you have probably had a little bit of wetness for a long time. The mats under the carpet are made to absorb a lot of water quickly, but they disperse it very slowly. At some point you might want to take the carpet up, (not out from under the seats, just at the front and back footwells). Either cut out replacements for the underneath matting, or spray a bunch of MicroBan on the matting, and even the carpet, (No I don't work for the company that makes Microban). It is probably not available in retail channels. But you can find it at commercial cleaning supplier stores. It comes in gallons only. which is enough for you, and everybody you know, for a lifetime.There is nothing that kills mold and bacteria like it does. It works for months, is the standard set for flood restorations, and general cleaning in hospitals. It is also a pet of the FDA, and EPA. FWIW.
1995 SE ..Green and Rattle Can...234K mi...Bonnie (she'll outlive me)
1998 SSEI .. White ..119K mi...Evey
1996 SSE ..MajTeal..157K mi...4/12- Dealer trade full of Lucas Trans fix