Leak in Passenger Compartment

[Jim A.]

Water leaks into the passenger side of my 1984 300 D Turbo. Settles in well of back seat on passenger side. Have ruled out sun roof as the problem and replaced the seals on both doors on passenger side. Leaks when raining whether it's moving or standing still. Car wash is the pits. Any ideas?

[psfred]

Rear window seal is shot. Water comes in the top, goes down the sides, and over the body lip, under the package tray sound deadening, and down the seat back.

Get it replaced, and plan on doing the front one soon, too -- 84 model is quite ripe for this little problem, and if you don't fix it the floorpans will go -- my 220D is probably non-repairable from windshield leaks, and we've spent a whole year fixing my brother's 75 300D.....

Peter

[MBJOE]

The most likely source of your leak is behind the Battery. I just got finished cutting , shaping and fitting my second firewall patch because the Battery acid had eaten a hole threw the firewall. This is a common problem on the 123 body styles. The hole in my 240D was only about 2 inches square but this latest one in my wifes friends 240D was more like 4 by 10 inches. Plan on the better part of a day it you are going to try this repair yourself.
Good luck

[mplafleur]

Watch out for those leaks! I also had the floor pans rot out of my '75 300D from leaks.

Did you check you sunroof drain lines?

I was plagued for years with baling out the rear footwell, I've baled quarts at a time and searched for the source for years to no avail.

When I first started with mercedesshop, I got the answer. I cleaned out the drains in the pockets under the hood hinges on both sides, and also there is a drain that allows water inboard where it finds its way into the passenger compartment under the battery just like MBJoe said, but ALSO another one under the master cylinder.

If you will be dilligent in finding and cleaning out these drains, I feel quite confident you will cure your problem.

The rear window seal is a real bear to replace, I would not replace it unless you determine FOR SURE that this is the source of your leak. I've never had any problems with rear window seals. Psfred has been a little less lucky than myself it sounds like.

Definitely clean out the drains with wire before replacing the rear window seal. Cleaning out the drains costs nothing. I don't want to even think about what it will cost to replace the window seal.

Good luck,

[psfred]

Larry:

$150 at the local autoglass shop my indy mechanic uses, $75 at others (with supplied OEM gasket).

For the brave DIY type: pull off all the metal window trim (carefully, it bends) with a good trim tool. The trim fits into the lock grove in the seal. Disconnect rear defrost wires in trunk. Cut seal between glass and body with strong knife -- have a care not to cut rear defrost wires. Lift window out of cut seal, pulling wires through the bottom corners. Remove seal from body and window -- best to lay window across a pair of sawhorses for this -- something flat may help break it. Clean window and body flange -- body flange must be rust free and smooth with good paint. Repair any rust or rough paint and let dry properly. Coat new seal with silicone spray and fit onto body flange. Lay a small (1/8") cord in glass recess with ends at bottom center of seal. Feed rear defrost wires down holes, with new seal bits. Lay glass on seal and pull cord out while forcing lip of seal over edge of glass all round -- helps to have suction cups and bar to hold glass. Two man job, alas. When lip is over glass all round, re-install trim to lock in place. Re-attach rear defrost wires.

This is easier than it sounds, particularly for someone who has done it a time or two. Glass shops tend to make a big deal about it because most of them pay crap and have only young, inexperienced help, who have never seen one of these on a car (still used for pickup rear windows!). It is also possible to force the seal lip back and remove the window IF no one has glued it in with black RTV sealant -- NEVER allow anyone to use this stuff on a "lace-in" seal -- it prevents conformation to the body, and will ALWAYS leak, usually from installation. Sad, but true!

Peter

Per svc manual:

1) Lay window on a supporting surface
2) Place rubber seal around window
3) Press in crome retainer***
4) Install greased cord
5) start gasket with smooth flat tool
6)pull string parallel with window as assistant is pushing in.


***it won't go in after (I learned )

[psfred]

Steve:

You could be right -- I've not done one in a long time, and that was on a pickup truck.

Theoretically the glass can be removed and replaced without ruining the seal, but I'd not try it on anything as old as what I have.

We will be installing both front and rear windows in my brother's 300D shortly (after we get the paint done) -- will report on ease then.

Peter

took me 45min for both windows, girlfriend helped. This was my first time. Important to center windows accurately. Be sure to install chrome retainer before putting window on car. I forgot on the rear and had to pull it and do it again. The MB shop manual has good instructions. Carefull the back window is much thinner than the windshield.

[afmcorp]

i'm with larry about the drain holes. the same also applies to the doors drain holes. these need to be cleaned out periodically so the water can have some place to go rather than backing up. and besides this check is cheap and if it works your $$ and time ahead of the game.