Ok so I have been having this problem with water inside my car after a wash or rain, on the drivers side floor, all the way from the gas peddles to behind the seat. So that was not good, especially after I just welded a new floor pan in there and put new carpets in. So I was thinking there might be a weather striping issue, it looked like it had seen better days (it is 35 years old after all ) so I replaced the roof rail and the under the door one (not sure the proper name).

So we have been getting a lot of rain these past couple of days and I get in my car to go to school this morning and I heard what sounded like splashing water when I closed the door, so I opened it and shook the door a little and there was defiantly water in there, and not just a little.

Looking back on this morning I didn't check the floor, i was to preoccupied with the door.

And yes the window was all the way up and the door was fully closed

 

Check the drain holes and plugs on the bottom of the doors. If the holes are clogged, open them up; same goes for the plugs--remove the plugs if necessary.

 

Like Dave said, lie down on your back and you can see the drain holes; probably stopped up with leaves/dirt/etc. Put a pick/toothpick/small screwdriver in there, then GET OUT OF THE WAY! LOL! Once you get the holes cleaned, they should drain OK. Hopefully, no rust buildup.

 

Ok I cleared it out, I am going to pull the panel off over memorial day weekend to clean it out. But how the hell dose water get down in there?

 

The outer window sweeps are not 100% submarine waterproof and so water goes down into the door and if the drains are clogged then you have sloshy doors...my PU ('69) was Ziebarted when new and the doors did the same thing when I bought it ('98) and the drains were full of black goooo