Whenever we have a long rainy day, my 240 gets water in the passenger side carpet. It only happens on the passenger side, I believe that the water is coming in the front and it finds its way down to the slightly lower rear seat footwell. Whenever it gets wet I have soaked it up with kitty litter and then vacuumed up the wet kitty litter. I had someone spray the side of my car with a hose for a couple of minutes while I sat inside but could not see any water dripping in. Are there any common leaks or things that I should check?

 

First, please say whether or not it has a sunroof?

 

Sorry, forgot to add that it’s 244 DL so no sunroof.

 

The windshields are glued in - and the glue gets unstuck along the sides or corners - so it leaks between the windshield and the body - the gap is covered with trim, but that's not a seal -

 

Should I assume that this is the problem or is there any way to test for it?

 

Run water down the side of the windshield - pull the plastic side panel and carpet back - look for water coming in

 

could also be leaking through the rockers maybe? spray some water through the louvers in front of the windshield.

 

another source of leaks, the windshield frame rusts through in the lower corners, and drips down the back of the dashboard.

you have to remove the windshield, then wire brush out as much rust and old glue as you can, carefully weld in small thin strips of steel to replace any places that are totally perforated, seal the whole area with a rust inhibiting sealer, then install a new windscreen, for which I highly recommend using a 1993 240 windscreen as they have an integral trim seal, you get rid of the funky old seal.

then there is the rear ventilation tray, under the back window. this has plastic drain tubes that go through the two front corners of the trunk, those tubes can get plugged up, and rainwater can fill up the tray, then dribble down the interior. I'd remove the back seat, lift up all the carpeting and padding you can, as well as the trunk carpet, and the cardboard/carpet on top of the parcel tray, and use masking tape to put pieces of blotter paper in various spots, so the next time it starts getting wet, you can see where its coming from.