Help, rain inside 123 sedan

check for perforated metal on each side of the firewall where the cables run in and out of, also make sure that the rubber grommets aren't falling apart.

there are also rubber grommets in the transmission tunnel, for draining the condensate from the ac and other things.

there's also a possibility of water entering in the chassis rails from the front wheel arches and leaking in thru rust holes in the inner sill.

Got any water in yout taillights? I've heard of one case where it came in through the gasket around the taillight assembly. I don't remember the details but the guy replaced the taillight gasket and that fixed his.

These leaks aren't uncommon. Google aorund a bit and you should fnd a few more causes.

You gotta be a sleuth here...

Does water ever enter the car when it is stationary? If so you can forget the wheel arch situation. You may have to remove some interior trim & carpets.

Have a colleague stand outside with a hose pouring on the roof, with you inside looking for the water route. Maybe lie on your back with a torch peeking up under the dash panel.

Most likely it's around the windshield - those seals can deteriorate without it being obvious.

good luck...

That's what I finally did to track down leaks on my 300SD that were driving me nuts. Even with a hose, it can be difficult. I could spray the whole windshield area, heater air intake by the wipers, corner pillar, door, roof, everything and no water would show up inside. Yet in even a light rain, in an hour water would be in the heater blower and on the passenger floor.

I finally tried letting the water gently roll down the windshield, instead of spraying it on. Then water made it's way inside. I had to remove the blower to see where it was coming from. With a mirror, I could see it. Turns out it was one of the holes for the plastic plugs that hold in place the front edge of the chrome air intake grill around the wipers. The plastic plug was missing. The water came through that hole, then adhered to the underside of the body, traveling about 4 inchs across, then finally breaking lose and dropping down.

I also found a leak in the trunk from around the rear window seal and even worse, from around the gas door lock. The dummies at MB designed the door lock with a vacuum actuated pin that goes in straight horizontal, requiring a rubber seal to keep the water out. If they had just angled it downwars, water could never get in.

Good news is she's dry now!

You need a helper and may have to try for quite awhile to find it. Try to work one area thouroughly at a time. Otherwise, even if it shows up, without tearing everything apart inside, you won't know which area it came from.