Water on floor 300D
 

Does anyone have any experience with the corrugated rubber hose that surrounds the vacuum lines and electrical wires passing from the body to the front doors? These are both torn on my 300D and I'm wondering if the water on the passenger side front floor can be getting in thru that way. Have checked the drain points under the hood and under the battery plate. All seems ok in those places. Where do the front drains for the sun roof pass down thru body and where are the exits? This could also possibly be the problem. Windshield gasket seems to be quite pliable so am hoping it is not the cause.

You want to check your a/c drain also. Pull the lower left panel from the pass side floor board and look up in there behind the radio area. You should see an intact drain line from the a/c evap box. If not, run you a/c and see if you see water coming from it draining to the floor.

Leak
 

If all your drains are clear, I'd bet good money on the windshield seal allowing a leak. Even though the seal material still seems pliable, it can shrink dimensionally and pull away from the metal lip of the windshield opening just enough to let a thin sheet of water get through.

Get out your wet-dry vac and remove all the moisture that you can. Also, lift up the rear-floor carpet and remove any water that may have migrated back there so you are not surprized later ...they may feel dry on the surface but could be wet underneath.

The seals are not prohibitively expensive and any glass replacement shop can do the job...some are more willing than others and the labor will vary from shop to shop. I suggest replacing front and rear at the same time but that is because both of mine needed it after years of South Texas sun. One caution, there is a risk of breakage especially if there are any rock chips in the glass, but if the installer is extra careful and is not rushed the replacement should happen without a problem.

The dual seal replacement on my '82 240D was needed after 20 years (and 300K miles) and the labor was 100 bucks for installing my mail-order OEM seals. Good fix

H2Woe
 

Dealing with that right now. Try hosing the hell out of the car. I found leaks in the windsheild that way. The roof wasn't leaking from the hose, but the 4 inches of rain it just got hit with seem to have shown the truth. There was much less water inside than I would have gotten, it but still sucks. Moral- you may have more than one leak. The amount of water you're taking in can tell you alot.

door corregated rubber
 

The rubber that connects the door to the A pillar is just a flexible conduit for the cables. When they are ripped, there is a higher chance that the vac cables inside will chafe or get cracked. One of mine did because of a decayed rubber tube. No big deal, it just took a lot of time to diagnose.

Leaks on mine were the windshield, the AC drain tube, and sedimented up hinge drains. Persevere and eventually you will get a dry car.

alec