I have a 1983 300DT, and a very strange phenom that happens EVERYTIME it rains, but I cannot reproduce by spraying the body with water from a hose!!!

Basically, the car ends up with water in the cabin floor and the mats are soaked. Thankfully MB undercoated (and intercoated) the body of the car but, the car is starting to smell musty etc as a result- and the mats are now shot (expensive to replace)

Anyway, the harder it rains, obviously the more water gets in. I have noticed that on the firewall, where the air intakes vent out water via a rubber hose in the engine compartment, the rubber hose is missing (passenger side)... I do not know if this is a possible area of concern.

Really wondering if any has had this problem an cured it?

Your help greatly appreciated.

Check sunroof drains in the door pillars, the area around the hood hinges for clogs and corrosion (you can get rust-out here, lets water down the firewall) and window gasket condition. Rear window seal can leak and allow water down the package shelf and behind the rear seat to the floor, takes a while to get there since it travels under the asphalt coating.

All the water ends up on the rear floor because that is the lowest part of the floorpan. Won't travel left to right, though.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Check the plastic grills by the windshield wipers. (I mean remove them and inspect).

But be careful getting the snaps out. It's a typical place for rust-rot and resulting water leakage into the passenger compartment.

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Toblin

'79 300D, "Liesel von Diesel", 235K

I kid proofed the house....but they still get in

in additon to the above you should get up into the front wheel wells where there is a plastic cover over an outlet for the drains coming from near the hood hinges. this is a clog prone spot and needs to be cleared on a regular basis as all the debris from above gets caught there.

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1984 300D Turbo - 231k....totalled 11/30/07 RIP

Thanks for the replys. Here's what I have found...

I did pry off the plastic grill behind windshield wipers and found to be clear, atleast on the pass. side where the water buildup is the worst. Since I didn't understand how these air intakes worked exactly (figured if they let air in why wouldn't they let water in?) I put a hose with a little pressure in there to flow and found a tube missing on the firewall (driver's side in tact) which directs water past the majority of the firewall, and then to the ground. This missing tube allowed water to flow over a/c metal tubing which comes thru the firewall via a gasket. This gasket leaks and allows a dribble of water in the cabin (passenger side floor). BUT does not seem enough to cause the lake which I receive when raining.

I assume if I am to check for sunroof and door pillar leaks, that i would use the hose to douse this area, after inspecting for blockages?

And I do get leakage to both side of the floor- rear floor is as bad as the front- ineteresting because there is a hump under the front seats that would seemingly stop flow from front floor to rear- if the front was the only place where water was leaking to.

Additionally, I took the plug out of the right trunk well area- this is where, in older models, the spare tire would have been located. Did this because I used to get considerable water there too.

I know this sounds like a sinking boat that needs bailing, and that it should be VERY simple to visually see where the leak is happening, but I have been in the trunk (closed!) and inside the car/cabin while a friend sprayed the car vigorously and over a considerable time, and the only place I could see water trickling was that pass. side grommet on firewall- very minimal.

This is not a rusty car at all but will look further at the rear window seals and sunroof/pillar locations (already cleaned leaves and other junk away from hood hinge areas- no rust there either)... as well as replacing the rubber hose missing on pass. firewall.

Thanks again, and given this lengthy thread's info, if you have anymore ideas- don't be shy. Thanks.

In the trunk, look for signs of water droplets landing on the wheel wells and running down. If you find these "tracks", for sure you have a bad rear window seal. Very common on the W123. The only water visible will be in the trunk, unless they get bad enough to show overflow marks at the bottom corners. You can pull the rear seat bottom cushion, too and check for water there. If you find any, rear window seal.

Other places to check are the sunroof drains (they go down the door posts, and if clogged, will run water around the base of the door onto the floor pan).

Bad door gaskets sometimes allow water underneath, too.

Front windshield will also leak invisibly down the firewall and under the carpet.

AT this age, I would suspect both front and rear window gaskets are bad and require replacement.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!