BIG Water Leak
 

The front floor passenger side of my 83 300D got soaked in a rain storm the other day. I pulled out the battery (none too easy mind you) the tray is badly rotted as is the area under the tray near what I am guessing is some wiring running into the body. The drain was plugged, I cleared that. I ran a hose and started to wash down the damaged area and confirmed water is flowing freely from underneath the dash :-( I will need to fill plug and seal the rotted out areas under the battery tray. Any recommendations as to what I should use? Body filler? Squirt foam in a can? Globs of tubed silicone sealer? Any advise is most appreciated.

Get some rust convertor or etch primer (same thing) and prime the rusty areas after removing free rust. Paint afterwords with good automotive enamel -- spray cans will work fine for this, you won't need to match color too closely.

For the repair, I would suggest welding in a piece of sheet metal if you can, if not, get a fiberglass repair kit and build up to the orignal contours if you can. Last choice would be foam or caulking, as they are not rigid enough to fix the problem premanently.

You will have better luck with the fiberglass from the inside if you can reach the appropriate area without taking the car apart.

Peter

Hello.

I used to have a similar prob with my 123 - water leak, front passenger side. After pulling out the carpet I located a rusted-thru area with dozens of small holes in it. Find someone who can cut the rusted metal out and have a metal sheet (zinced) CO2 welded across from inside (it would be best to have it welded from outside beneath the bonnet but there is no good access). After it is welded have it painted, put the carpet back on, scratch all the rust you can off from underneath the bonnet, apply rust inhibitor primer, and have it painted with approximately the same shade of colour. People also put an asphalt-like paint over the inhibitor and then the original shade of paint. The effect of having asphalt paint applied after a primer is that it seals every tine hole or space where water could penetrate and carry on the rusting process. The disadvantage is that the paint is mostly black so have it painted over with an original paint and that is it.

I used a fiberglass repair kit to fill in after using rust paint. My leak was right behind the firewall at the drivers side. My gas petal foot would get wet going down the road. Been dry for a year now.