water leak assistance please - PeachParts Mercedes-Benz Forum

psaboic · #1 06-13-2011, 02:00 PM

I know it has been discussed ad-nauseam in the past, but frankly doing a search sends me in several different directions doing nothing but getting me more confused.

On my 83 300D I have a front passenger side water leak that has gotten progressively worse over the last three months. I looked at it today while it was raining and found that the water is coming in from under the passenger foot kick panel by the door, making the side carpet wet and soaking the floor mat.

What do you think the cause is in most probable order. Sunroof drain, door bellows, windshield seal?

Thanks for the help in advance.

Glenn

Jeremy5848 · #2 06-13-2011, 02:34 PM

I can't prioritize your list but there's a fourth item you should add: remove the battery and its pan and check underneath for rust.

vstech · #3 06-13-2011, 02:38 PM

yeah, but that leak usually fills the well from the front, he's getting water from the side... more likely the door seal of some type.
also the door drain holes need to be clear, or water gets up into the trim and spills out in the car under the covers... how are the window felts?

psaboic · #4 06-13-2011, 03:59 PM

Well, I got to thinking, the PO replaced the windshield and seal before I purchased the car, so..............I did a little poking with a plastic screwdriver on the inside of the windshield seal near the dash. When I pushed on the seal near the right lower corner, I easily pushed out several drops of water. Tried it at the same place on the outside and got the same thing. Rest of the seal was dry inside and out when tested.

So, I'm thinking I need to get the windshield re-sealed. Not sure if it is the cause of my trouble, but it ain't helping.

Any tips I need to know about the windshield and seal before jobbing it out?

patbob · #5 06-13-2011, 04:51 PM

Likely the windshield seal -- they're designed to leak. If its leaking there, you may be able to see it leaking down the inside of the windshield seal far down in the corner.

Another spot is through any missing rain gutter screw holes -- those are through holes into the pillar and a good flow of water can easily enter under fairly modest conditions. Run a hose to flood the gutter and you can watch the water dribble out the weld holes at the base inside the cabin up under the dash.

Orv · #6 06-13-2011, 06:11 PM

Is this a "drive it until it wears out" car, or a "keep it forever" car? If it's the former, I've had good luck injecting silicone sealer under windshield seals to reseal them. I usually use the really thin "windshield sealer" stuff for leaks between the seal and glass, and the thicker stuff for leaks between the seal and metal. Works on those pop-in side windows (like the rear quarter windows on wagons), too.

If it's a "keep it forever" car, the only right way to fix it is to take out the windshield, fix the rusty metal that's under the seal, and then reinstall with new rubber.

Codifex Maximus · #7 06-14-2011, 02:50 PM

Don't forget to check the cowling drains into the engine compartment. They look like plastic pinch tube protruding from the firewall.

Mine got slightly melted from the heat of the turbo and closed up tight. This caused the fresh air vents next to the wipers to fill up with water on the passenger side. This caused water to backup into the ducting leading to the blower motor (shorting it out) and soaking the passenger side floorboard.

Solution? Replace tubing - easy and cheap. Replace blower - easy and expensive.

psaboic · #8 06-14-2011, 08:10 PM

Well, today I worked on the car a bit. I checked the door bellows and they are fine. I ran stiff weed-whacker line down all the sunroof drain holes then poured water down them. They drain fine and no leaks. I checked the cowl drains and they are clear, ran water down them and no leaks. Lastly, I checked the door drains. they are open and clear and the window felts are nice and tight against the glass with no tears.

I'm still thinking it is the damn windshield seal.......Any other ideas or????

Glenn

indybenz · #9 09-03-2012, 09:46 AM

I know this is an old post, but any solution?

shertex · #10 09-03-2012, 09:51 AM

Check for holes in wheel wells.....that was my problem AFTER I had gone to the trouble to replace the windshield.

rscurtis · #11 09-03-2012, 10:18 AM

Check the drains in the area of the hood hinges. I had the same problem on my '83 once and that was the problem. There is an upper and lower drain on each side. You'll have to remove the battery to gain access to the lower drain on the passenger side.

rbc · #12 09-03-2012, 10:51 AM

Had same problem. It was rotted battery tray further rotting mount for battery tray. used a combination of rubber roofing adhesive strips (6") and spray on sealant to do the trick. no leak.

charmalu · #13 09-03-2012, 11:07 AM

The OP never came back to do a follow up.

Remove the Battery and tray. there ae several sheet metal pieces that are welded together when the body was assembled. Battery acid over the years can and will eat through the paint and get down under the seam sealer to cause rust betweeen the seams.

Remove the front wheel and the splash panel. the early 123`s is a short piece behind the wheel, and from about 82 on it is a full piece front to back held in with about 6 8mm screws.

With the shield out you can see where the metal inner fender is spot welded to the body. the rust from above in the seam can and will eat down where you can see from below. bad enough and there will be a hole into the pass compartment.

Notice with the shield out the amount of dirt/debris built up behind the lower part of the fender. this is another place rust can start. I think this is where the rust starts in the Rockers. also the wall behind the fender isn`t sealed or painted very well from the factory. I have seen some rusty ones when I have pulled fenders at PNP and on my 85.

On the drivers side under the Fuse box is 2 rubber Grommets. below them is a flat piece of metal and a seam.
I have my MC & Brake Booster removed to replace the Sway Bar. cleaning things us noticed in the seam (which has seam sealer) it looked like rust starting. digging along the edge of the sealer it lifted up and there was rust. got it dug out, degreased, etc... then laid in the POR-15. using an Acid brush I then used the POR-15 Seam Sealer (Por Patch) POR paint in a paste form.

I wouldn`t have found this if I hadn`t decided to do the Sway Bar project. and this are under the fuse box hadn`t been cleaned out in the 27yrs of the cars life. I sealed every seam and spotwelded part while I was in there.

This is a yearly inspection that has to be kept up on.

Charlie