Mercedes 84 Trunk flooded....drain..
 

Hello,
There is water in the trunk of my 1983 300D Mercedes, and behind the passenger seat.
This happened before, and my mechanic said he got under the car and there
is a drain??...I did A search and found this advice....Still confusing to a novice. Would the direction pertain to the Trunk cover in the back of the Car or theCover in the front. It would be great if I could do this myself and save money and a trip to the mechanic...Here are the excellent directions for this..Anything to clarify is useful advice. Thanks!

"Here's the cure for flooding:

Open the hood and look for some little dimple openings at the rear of the hood hinge pocket. There is a vertical piece of sheet metal in the middle of this area and there is a little opening at the bottom of this vertical piece of metal that also must be clear. The dimple at the rear allows for a drain between the fenderwell and the firewall.

In addition to those two dimples at the firewall and the two in the vertical pieces of metal, there are some drains underneath the master cylinder and the battery box.
I must warn you that cleaning these drains requires very skilled use of a highly sophisticated tool. This tool is a piece of baling wire (for city folks I'm quite sure that an old coat hanger will provide an adequate substitute for baling wire.) Using your sophisticated, high tech tool clean all six of these drain areas thoroughly.
I know it sounds nuts, but it worked for me."

What ever works. Hardware Stores sell different sized steel wire in various diameters. Like I used when I was a Teenager to wire my Muffler up in place.

In the hood hinge and spring pockets on the front even if the drain is plugged at one time it was all nice and sealed to prevent water from getting in. So you might want to take a good look for holes rusted through in those areas.

It was I think over 5 years ago I had the rusted through holes in the hood hinge spring pockets. I do remember the end of the drain inside of the fender well was plastic and I took an Air Gun with a needle attachment and stuck it in the bottom and blew and I got lots of Pine Needles and other crud out of the top.

I also believe that under the floor mats there is some plastic plugs that you can pull up to drain out the Water from inside of the Car.

I have had water in the Trunk but it was caused by holes under the rear window rubber. I can't remember if there was drains or not. My guess is there is drains somewhere or plastic plugs.

On a couple of American Cars that had leaks that cause water under the floor mats I drilled some holes in the floor to allow the water to get out. Although to day it is raining a bit hard in CA where I am you normally don't have to ford puddles deep enough or long enough time that would allow water inside if you drilled some holes in the floor.

lj, careful with the wire. Some of the drains are connected by rubber hoses. A safer bet is weedwacker line.

Good news is: There are drain holes in both trunk wells under the plastic liners and also in the spare tire well. They should have removable rubber plugs.

Bad news is: The water incursion is probably from a rusted out rear windshield channel.
It was on my '83 300CD.

Medium news is: Unless you are a body welding wizard it is a job for a body shop to rebuild that channel. It is not as expensive as you might think. It cost me a total of about $400.00. That included a pro glass shop windshield R&R and a new gasket. The coupe rear windshields are rare in the extreme so I took no chances.

If you are talking about the boot / trunk area then there are plugs on either side of the the little wells behind the rear wheels and one in the spare wheel well. To get to the sides you need to remove the plastic liners. You can reach the plugs from under the car but it is often best to make sure everything is dry on the inside as soon as you can.

The leaks for this back part of the vehicle usually happen because of failure of the back windscreen (rust), the rear lights, the trunk / boot seal, the overflow + seal around the fuel filler cap and if you're really unlucky rusty sunroof drains on the C pillar (saloon / sedan)

########

If you've got a wet rear passenger floor then the leaks at the front of the vehicle need to be considered (along with any sunroof leaks)

You don't need to do any welding unless you want to.

After the rust is dealt with and painted (rust converter or anti-rust paint) over I have used epoxy putty and a polyester mesh fabric and JB weld to do rust hole repairs. Thin Fiberglass Cloth could be used.

See the pics. I glued the fabric on with JB Weld Epoxy and used a hair dryer to speed up the curing.

The normal JB weld has a long cure and it can run. The 5 minute type JB weld does not run as much since it hardens faster.

D911's method is fine for non-critical rust hole repair. I have used it myself. I would not however use it to rebuild a critical channel to seat a windshield.

Using filler materials is also restricted in certain parts of the world (for good reason)

Except JB Weld is an epoxy, not a filler. It may even be stronger than the original metal if prepped well. As usual, preparation of the surfaces is the key.

Don't forget the antenna mast grommet for a leak source.

W123 Trunk Water Ingress
 

Water in the trunk isn't coming from the windshield, maybe the back light .

I've found some with the drain tube in the fuel filler well loose, you have to remove the tank firewall to see, then it's a very simple thing to correct .

The rubber drains in the trunk floor are beginning to age out and crumble, luckily they're the same as some W124's and maybe W126's ~ I simply took a dead one into the junkyard and matched up the hole size .

Remember : you'll have to keep this rubber clean of oil as well as gravel, leaves or any other debris or the water will just puddle up and never drain out .

Glue is only as good as the immediate bond to what ever paint / rust / metal is left.

Rusted out hood-hinge pockets led me to sell my '84 300D. In a hard rain the rear seat footwell carpet would be soaked. I considered the j-b weld repair, but to do it right the fenders have to come off and the dash. I wimped out...

I think it depends on how bad it is. There has to be enough metal that you can treat for rust for the in my case polyester mesh cloth to be epoxied in place and then coated.
After that it is just a matter of coating it as you see fit.

I did not do this but after you repair the inside it is possible to spray it with a sealer like FlexSeal.

I use the JB Weld because it is what I have and the Polyester Mesh Fabric is part of a type of roofing system where you roll out the mesh and coat it with a rubberized liquid coating. So I also have the mesh.

I buy the slow curing J-B Weld with the 5 ounce tubes (I bought 5 sets I found a cheapie tool and industrial supply store that sold them cheap for like $12 when places like PeP Boys sold them for $17) instead of the typical 1 ounce tubes you see in the hardware stores, Walmart and so on. I have the 1 ounce tubes of the quick dry J-B Weld and use several companies epoxy putty as needed.

I have tiny experience with Bondo/body filler and that over 40 years ago and the body filler is not much use for other stuff as the J-B Weld is.

Watch.....
 

Watch Kent's tips on YouTube about trunk leaks. Some of the leaks might come in through sources other than a trunk seal that you really didn't think about. Like you were saying, it could be that no water there is able to DRAIN out in the first place. The other thing is water could be coming in through the trunk seal or through the brake light gaskets or through the antenna gasket, rear window gasket, etc.

Good luck.

LJ; To pinpoint the source of the leak(s) I closed myself into the trunk with a flashlight and had my wife (who I obviously trust) flood the rear of the car with a hose.

Not a job for a claustrophobe and make sure your assistant loves you.

Trunk Leak Finding
 

I wish I could fit in the truck like you do....