Standing water in rear passenger footwell finally gone.
 

Standing water in rear passenger footwell finally gone.

I have been dealing with an inch of water in the rear passenger footwell since the winter rains started about 6 weeks ago. Reading all the posts, and attempting to diagnose during daylight hours without a hose (urban apartment dweller) has been pretty tough. At long last, I have evidence that I finally fixed the leak. Based on other posts, here is what I checked, in order.

1. Clean hinge drains - both sides were sedimented closed. Didn't help.
2. Clean front wheel well drains - both sides had some gravel in them. Didn't help.
3. Check for perforated firewall below/behind battery. No problems there.
4. Check sunroof "A" pillar drain. Removed blockage caused by decomposed rubber from the sun roof lifter. Didn't help.
5. Check rear sunroof drain. Working fine.
6. Check sunroof seals. Working, but replaced the rear seal as it was fairly cracked. Didn't help.
7. Check door, rocker panel, and rear wheel well drains. All were fine.
8. Check air intake tray for perforations. No problem there.
9. Check condensate drain. Probably some leakage there, reconnected the rubber tube, sealed and didn't help.
10. Check windshield seal. Initially, it looked pretty good since this is not the original windshield. Apon further inspection, the seal was overlapping the "A" pillar decorative trim (trim that runs the legnth of the wagon- from based of windshield to rear tail light) about 6 inches below the top of the windshield. The overlapping window seal was wrongly placed for about 6 inches. I loosened the three phillips screws the hold the trim down, tucked the seal under the trim, and ran permatex black rubber sealant down the joint between the two from the rain gutter to the base of the windshield.

I think that I am through the woods on this one, but will ammend this if not.

Hopefully this will help someone else with a leaky 123.

I had the same exact standing water problem in the same place on my '85 300D. The carpet behind the front passenger seat would be soaked after every rainfall. Instead of going through all the trouble of finding out where the leak was coming from, I just drilled some small holes through the floor plan where the water was accumulating. Its been dry as a bone since.

Scott

Sometimes when there is a leaky battery, a hole will rust through in the firewall which will leak sometimes.

If the windshield seal wasn't right, wouldn't the floorboard in front of the front passenger's seat have been getting wet as well?

Cleaning the upper hinge drains made my left side rear floorboard dry as a bone, but the right side is still getting water...just in the rear; the front's dry unless I'm driving (haven't done that in a couple weeks :() and hit the brakes (I've watched the water flow from the rear to the front). I think the drain below the battery's clogged; I just haven't gone through with doing that yet...don't especially want to pull the battery, eh?

I should do that before getting the car back on the road...

i have seen the rust under the battery tray syndrom a couple times.

The water runs down the firewall and under the sound deadening material to the back floorpan where it collects (this is the lowest part of the floorpan).

Unfortunately, extra drain holes will keep the space between the floorpan and sound deadening wet, and this will rust out the floor eventually.

I'd replace both windsheild gaskets when I had a chance -- if the rubber that contacts the body isn't flexible, the gasket is shot. Water will leak in over the seal lip and run under the sound deadening material and into the trunk, causing lots of rust.

Don't use any sealant -- the gasket will take a while (a week or two ) to completely conform and seal, and all the sealants I've seen set up too fast. This results in a windshield that leaks from the day of installation, even with a new gasket.

Replacing the gasket isn't a big job, unless you have to repair the paint underneath first -- the paint must be intact and prefectly shiny, or it will leak.....

Peter

Where are the hinge drains?
 

Hi Folks:
Welcome me to the water leak club. I have this problem behing the drivers seat on floor pan. I ended up repairing the floor pan but water still leaks. I cleaned the sunroof drains, the front tire wall drains. No luck it still leaks.
Now my Q is where are the Door hinge drains and where is the behind battery drains. Does any one have the diagram of drainage system for 1985 123 sedan?

May be cleaning one of these will help. My seals look all ok on window and winshields. I am also frustrated with this leak business. Please help.
MVK

MVK,
I had the same problem you do. No matter how many drain holes I cleared up, I still got water in the rear behind the driver's seat. Take a flashlight and take a look at the pocket where the inner hood hinge on the driver's side is (where the hood spring attaches to the body). Clear out all the debris and start poking around with a screwdriver to see if there are any soft rot spots. If there are, break through the metal with the screwdriver to indentify exactly where it is. I had a hole the size of two quarters in there which let water in past the firewall, below the driver's floor, and into the rear seat well. I used roof flashing compound, which is a polyurathane type tar that is flexible and weather proof, and tin foil to patch up the area. I'd put the compound on small sheets of tin foil and then layed them over the hole. I did this many many times so that the patch was a inch or so thick. If you do this, make sure you don't leave any mini-pockets where water can accumulate, that is, make sure the compound/tin patches are nice and flat, and are at an angle such that water will dribble down them towards the water drains. Good luck.

Alex

Thnaks Alex for a quick reply. I will check it out as sson as the weather warms up a bit.

MVK

update on original post
 

Well, after three days of rain, I still have some water dripping in from somewhere, but the volume seems to be decreased by about 90%. There isn't even enough to make it to the back floorboard, but I can feel some dampness in the A pillar padding.

Looks like I get to do some more diagnosis this weekend, but I bet it is a perforation in the hinge area (I could see a 1mm rust spot on the newly black painted hinge area) or a leaky windshield seal like PS says.

later

B pillar? Try the sun roof drains. I haven't had a problem with these, but I think I heard someone say once that water might accumulate around the pillars and rear dome light.

Alex

I have the same problem with the leaky floorboard in the front passenger floorboard and behind and the trunk(arkansas's been getting alot of rain if you watch the news, and theres like 4 in. in the trunk).

__________________
83' 4spd man 240D

Water will leak into the trunk from the tail lights. You have to pull the tail lights, either run some sealant on the gasket, reverse the gasket from one tail light to the other, or get new gaskets. I had water in my trunk and I just reversed the gaskets. I've had a dry trunk since.
Now I have find what solves my rear foot well pond problem.