Hi,

I have a 1990 300D(2.5TD) with 165K miles and I noticed today after a very heavy rainfall that the rear passenger carpet behind the driver's seat was soaked.

I lifted the floor mat and it seems that the carpet is wet by the side pillar, along the carpet fold closest to the door and towards the rear seat.

Does anyone know where I can check to see where the water might be coming in from? Is it possible that it is coming from inside the left rear wheel well where dirt usually accumulates? Could it be the sunroof?

I would appreciate any sharing of common problems or areas I can test. Thanks!

Best Regards,
Louis

I had the exact same leak - and my source of the water was the missing large rubber plug in the rear wheel house, its the largest one that is at the front edge of it. If its missing you will get a gallons of water in the interior while driving.

There is also a funnel shaped rubber disc along the floor edge very near to the wheel house - its actually two grommets in one - if they plug up or are missing water will end up in the interior.

The rear footwell position is the lowest in the W124 so even a front water leak ends up in the back.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Ditto on the wheel wells. Try to figure out if water only gets in while driving. If it gets in while sitting in driveway as well as while driving, then its water from above, not below.

__________________
14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Thanks for the recommendations and the areas of focus! It seems that the rubber plugs in the wheel wells are fine and are not cracked or missing.

I will perform some tests with a hose to determine the source. Thanks for the guidance.

Best Regards,
Louis

if the carpet is wet by the side pillar - then you need to check the door seals at the front edge of the rear doors or the rear edge of the front doors, use the paper trick to see if the rubber seals tight against the body, if it doesnt then check with garden hose on wide angle spray setting and try to get water between the door rubber and body, if you see water from the inside of the car - you just found your leak.

unbranded or replacement rear door rubbers are not shaped correctly at the edges where the door meets the window frame. They leave a gap there. if yours is that case you can try to build it up with some rtv and saran wrap.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

It seems on my E420 W124 1995 I had this problem caused many electrical things to short out Alarm, front seat control module, and door lock pump, also a resulting direct ground caused a fire under floor plate front passenger side, I tried drains on cowl, sunroof, windshield rubber seal, blower motor seal, etc it ended up being these rear plugs in the wheel well. Now I have a lot more repairs to be done.

windshield gaskets are also a prime suspect for water in the cabin. It runs to the low point behind the front seat under the carpet.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

How about the sun roof drain tubes ,do they exit down the door pillar .Next one is the membrain in the door ,this covers all the holes in the doors ,like a plastic cover .

Also check the drain from the climate control system. If that hose is missing/deteriorated, water will get into the cabin and, as previously noted, end up in the rear seat footwell.

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
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